ALBERT

Notes: The general theory of irreversible processes in solutions of macromolecules, previously formulated by the author, is reviewed. The theory is based upon the Oseen method for determining the perturbation in the hydrodynamic flow pattern produced by the frictional forces exerted by the macromolecule on the solvent, and on a generalized theory of Brownian motion in molecular configuration space. Applications of theory to viscoelastic behavior, flow birefringence, and the Kerr effect, and to dielectric dispersion are presented in outline.

Notes: From the close correlation between viscosity increment and streaming birefringence in dilute solution the parallelity of both effects in concentrated solutions is deduced and proved by the results on nitrocellulose, polystyrene, and polyisobutylene samples. By plotting birefringence vs. (η - ηl)q and the extinction angle vs. (η - ηl)q/c, the optical anisotropy and the stiffness of the single macromolecule can be obtained from measurements at fairly high concentrations, where the effects are large and therefore easily accessible.

Notes: A treatment is given for the Brownian deformation of an elastic sphere which permits extension of the theory of the Maxwell effect of solutions of elastic spheres to arbitrary values of the ratio of the time of establishment θ′, of a preferential orientation to the deformation relaxation time θ of the sphere. For large values of η0/ηi the (ratio of solvent viscosity to internal viscosity) the effect reduces to the simple deformation effect described in previous papers. For decreasing values of η0/ηi the deformation effect is gradually replaced by the orientation effect (orientation of elongated configurations). The influence of the intensity of the fluctuations as measured by the mean square value δ02 of the deformation coefficient is discussed. Values of δ0 are given for a series of polystyrene samples of increasing molecular weight. The theory is in qualitative agreement with experimental results on solutions of chain molecules and leads in particular to a new interpretation of the data for thymonucleic acid. The incompatibility of the Kuhn and Kuhn dumbbell theory with experimental results is discussed in more detail than in previous papers.

Notes: Les résultats classiques concernant les solutions de particules rigides sont brièvement rappelés (théorie de l'orientation). L'éxpérience a montré que la théorie avait une valeur quantitative. On examine ensuite en détail le cas où la particule est déformable. Cette question s'est considérablement clarifiée au cours des dix dernières années. La nature de l'effet présenté est déterminée essentiellement (1) par l'intensité des fluctuations de forme de la molécule et (2) par la durée de vie d'une configuration donnée. Il en résulte que le phénomène peut ětre dans certains cas extrěmes (1) un effet d'orientation analogue à celui que présentent les solutions de particules rigides, (2) un effet de déformation pure complètement différent du précédent. Dans le cas général il y a superposition des deux effets. Pour une molécule donnée il peut y avoir passage continu de l'effet (1) à l'effet (2) lorsqu'on modifie la valeur de la viscosité du solvant. On considère en particulier le cas des solutions de hauts polymères. Les théories pour les deux effets (1) et (2) mentionnés ci-dessus, ainsi que pour le cas intermédiaire, permettent de comprendre dans une large mesure les phénomènes présentés par ces solutions. Il existe un critère expérimental permettant de déceler si l'effet présenté par une solution donnée est principalement un effet d'orientation ou un effet de déformation. Il est possible de relier les grandeurs observées à des coefficients moléculaires, au moins dans les deux cas extrěmes mentionnés ci-dessus. Du point de vue expérimental il est intéressant de coupler les mesures de biréfringence d'écoulement avec des mesures de viscosité spécifique, viscosité statique et dispersion de la viscosité (ondes de cisaillement de fréquence ultra-sonique). On indique finalement sur quelles bases générales une théorie pour les molécules en chaǐnes pourrait ětre développée.

Notes: Dans cet exposé qui constitue simplement une brève revue critique l'auteur résume rapidement les résultats classiques de la théorie de la diffusion de la lumière par les solutions macromoléculaires étendues et souligne les hypothèses simplificatrices qui ont permis les calculs. Il examine en particulier le cas où les dipǒles élémentaires ne sont plus isotropes et montre les conséquences importantes des nouveaux résultats obtenus.Il s'attache en particulier à l'examen du cas important où la solution contient des macromolécules en chaǐne linéaire et résume les plus récentes tentatives qui tendent à traiter les configurations réelles de la molécule et non plus celles d'un “random flight” fictif.

Notes: Melting temperatures of cellulose trinitrate (13.96% N) in mixtures with γ-butyrolactone have been determined dilatometrically, and also by an optical method depending on depolarization of polarized light when transmitted through a semicrystalline sample. Results obtained by these two methods, and also by direct visual observation, are in good agreement. Whereas the dilatometric method is preferred for higher concentrations of diluent (volume fraction v1 = 0.86 to 0.68) where the melting point is below 80°C., gas generation by decomposition necessitated abandonment of this method at the higher melting temperatures for lower diluent concentrations. Adoption of the optical method permitted determination of melting temperatures as high as 116°C. (v1 = 0.60). The results have been treated according to the thermodynamic theory of melting of polymers. While the results do not extend far enough to allow definite assignment of the melting point Tm0 of the pure polymer, they indicate that it is at least 1000°K. The heat of fusion per structural unit is low - not over 1500 cal. per repeating unit, or 5 cal./g. The low value of the entropy of fusion - less than 1.5 cal./deg./mole of units-indicates limited flexibility of the chains in the liquid state. The high melting point of cellulose trinitrate is a consequence of its low entropy of fusion, and cannot be attributed to large intermolecular attractions in the crystal.

Notes: Nous avons groupé dans cet article les principaux résultats d'un travail, dont le principe consiste à mesurer au microscope électronique les dimensions des particules colloïdales rigides utilisées comme modèles, puis à calculer à partir des dimensions la viscosité intrinsèque [η], les constantes de diffusion de translation Δ et de rotation D ainsi que la constante de sédimentation s. Ces paramètres calculés à l'aide des théories fondamentales sont ensuite comparés aux valeurs expérimentales mesurées par les techniques correspondantes et la comparaison des deux groupes de résultats doit permettre de juger de la validité des théories mises en jeu. Dans le calcul des valeurs théoriques nous avons tenu compte de la polydispersité et nous indiquons comment nous avons calculé les valeurs moyennes apparentes de \documentclass{article}\pagestyle{empty}\begin{document}$[\bar \eta ], {\rm \bar \Delta}, {\rm \bar D} $\end{document}. Les mesures de viscosité, de diffusion de translation et de sédimentation effectuées sur un sol de V2O5 donnent des résultats dont la comparaison avec les valeurs théoriques calculées à partir des dimensions n'est guère possible de manière quantitative en raison de l'imprécision de celles-ci. Mais l'utilisation simultanée des valeurs expérimentales de [η], Δ, s, nous conduit à la conclusion que le sol de V2O5 se comporte comme un sol monodispersé d'ellipsoïdes de révolution rigides de 1692 Å de longueur et de 44 Å de diamètre, or 40,3% des particules de sol étudié ont pour dimensions 1607 Å de longueur et une section rectangulaire de 100 sur 50 Å. La détermination de D par birefringence d'écoulement conduit à un désaccord considérable avec la valeur calculée de D̄ et ce désaccord semble dǔ à la présence dans le solvant d'acides vanadiques qui perturbent l'orientation des bǎtonnets. L'étude d'un sol de virus de la mosaïque du tabac a donné un bon accord entre la valeur calculée D̄ = 205 c.g.s. ± 20% et la valeur mesurée D = 260 c.g.s. ± 20% ce qui constitue la première vérification expérimentale de la théorie de Peterlin et Stuart. Cette étude a permis de calculer l'indice de réfraction de la particule de V.M.T., on trouve n1 = 1,58, n2 = 1,59, ce qui corrobore les valeurs trouvées par d'autres employant des méthodes indirectes. Enfin l'étude d'un sol aqueux de noir de carbone a permis d'observer un accord convenable entre \documentclass{article}\pagestyle{empty}\begin{document}$ \bar \Delta $\end{document} calculé = 1,10 · 10-7 c.g.s. ± 15% et Δ mesuré = 1,37 · 10-7 c.g.s. ± 10%, ce qui montre la validité de la loi de Stokes pour des sphères dont le diamètre est de l'ordre de 1 à 200 Å. Ce sol présente d'autre part de l'effet électro-visqueux et la constante d'Einstein K = 2,5 est trouvée égale à K = 7,8 ± 0,5. On donne quelques résultats concernant l'étude de l'effet électro-visqueux de ce sol.

Notes: A theory of the excluded volume of branched molecules has been developed. The model of the branched molecule is a main or backbone string of beads from which side branches (which are themselves unbranched) originate. Each of these beads has the property of the Kuhn statistical chain element. The calculation is based on the Fokker-Planck equation as used by Hermans and collaborators. The differential equation obtained therefrom is not solved, but the average squared distance between two segments on the main chain is obtained. It is found that this quantity \documentclass{article}\pagestyle{empty}\begin{document}$ 〈 r_{t_p }^2 〉 _{Av} $\end{document} contains a term proportional to (t - p)3/2 power, which term arises from the contribution of the branches. The radius of the molecule, which can be measured by light scattering techniques, contains a term proportional to the molecular weight to the three halves power if the length of the branches does not depend on molecular weight. It is suggested that the dependence on molecular weight of the relation between molecular size and branching could be used as an experimental check of the theory.

Notes: The molecular weight, the size, and the second virial coefficient have been determined for a series of styrene polymers prepared under high pressure (0 to 4000 atmospheres) using light scattering techniques. The intrinsic viscosity-molecular weight relationship, the size-molecular weight relationship, and the magnitude of the second virial coefficient reveal no significant differences when compared to similar data of regular polystyrene. Structural differences due to the method of polymerization do not exist to the extent that they can be revealed by such measurements.

Notes: With a view to finding a better method of separating the different components during electrophoresis on paper, we have carried out the electrophoresis in two dimensions, first flowing the current in one direction and then at right angles to that direction. For this purpose we used square paper sheets between two glass plates of the same dimensions. The electrical behavior of the material to be analyzed was tested before electrophoresis, so that it was possible in each instance to establish the duration and the different electrical characteristics of the two periods of electrophoresis and also the best initial position for placing the material. The experiments show that the components are found along a straight line, the position of which is determined in the plane by the characteristics and time flow of the current during the two phases of the process. Referring to the initial position of the material, each individual component is to be found at the extremity of the hypotenuse of a right angled triangle, the other sides of which are formed by the paths made by the substance in the two different phases of the process. The obvious advantage of the two-dimensional electrophoresis on paper is that it is possible to trace, on the same sheet of paper, the path taken by the different components under two different electrical conditions.

Notes: Styrene and methyl methacrylate have been polymerized at 25° using α,α′-azo-bis-isobutyronitrile labeled with C14 as initiator. The numbers of initiator fragments per polymer molecule have been determined by measurements of the average molecular weights of the polymers by osmometry and the specific activities of the polymers and the initiator by gas counting. It is found that polystyrene radicals combine at 25° and that for polymethyl methacrylate radicals at this temperature disproportionation occurs about twice as frequently as combination.

Notes: A selected monomer containing a photosensitizer flows along a capillary at a defined rate into a suitable receiver. Very high concentrations of free radicals (up to 10-4mole/l.) are produced at a selected point by focusing into it a large proportion of the radiation from a capillary are lamp. These polymer radicals grow to a chain length determined by the time spent subsequently in the capillary and it has been demonstrated by a utilization of the theory of the nonstationary phase in chain reactions that most of the radicals can be introduced into a second monomer contained in the receiver. That their continued growth in the new environment leads to the synthesis of block copolymer has been proved by examination of the ultraviolet spectra of the products.

Notes: Une dizaine de fractions ont été séparées par précipitation acétonique d'une solution aqueuse d'alcool polyvinylique commercial à 25°C. Le taux d'acétyle des huits dernières fractions était à peu près uniforme, soit environ 14·10-5 éq./gr., le polymère brut en contenant 33.5·10-5.Des études classiques de viscosité, ultra-centrifugation, diffusion brownienne, pression osmotique et diffusion lumineuse ont été alors réalisées sur trois de ces fractions (la troisième dite A, la septième dite B et la dixième dite C et aussi sur le produit brut.Leur viscosité intrinsèque [η] a différentes températures et dans trois solvants (eau, eau-dioxane à 10% de dioxane et eau-dioxane à 33% de dioxane) a été déterminée et l'on a déduit l'énergie d'activation de la viscosité intrinsèque soit 1,630 K. Cal./mǒle pour l' eau, 0,675 K. Cal/mǒle pour le mélange a 10% et 0,530 K. Cal./mǒle pour celui à 33%). En vue d'interpréter cette énergie d'activation la théorie de Flory et al. a été appliquée aux trois fractions et l'on a pu déterminer les paramètres entropiques Ψ1 et enthalpiques k1 pour les trois solvants considérés ce qui a permis la discussion des variations avec la concentration du polymère des énergies libres partielles de mélange \documentclass{article}\pagestyle{empty}\begin{document}$ \overline {\Delta F_1 } $\end{document} qui sont toujours négatives alors que le signe des entropies et enthalpies de mélange correspondantes dépend de la nature du solvant. Pour la fraction A l'accord entre les paramètres enthalpiques déterminés par mesure de pression osmotique et par la théorie de Flory est excellent.Pour évaluer la masse moléculaire en poids Mw par la relation de Svedberg l'estimation de la constante de sédimentation était faite en se basant sur la relation d'extrapolation: \documentclass{article}\pagestyle{empty}\begin{document}$$ S = \frac{{S_0 }}{{1 + kc}} $$\end{document} k valant 0,59 pour la fraction A, 0,42 pour la fraction B, 0,30 pour la fraction C et 0,60 pour le polymère brut. Les constantes de diffusion Da et Dm ont été mesurées par la méthode de Lamm à 20°C. pour les fractions A, B et le polymère brut tandis que pour la fraction C on a uniquement d'éterminé Da par la méthode du “scanning” de Longsworth.Les pressions osmotiques ont été estimées dans l'osmomètre de Fuoss et Mead sur le polymère brut et sur la fraction A à 25°C. en solution saline.Finalement les expériences de diffusion lumineuse réalisées aux trois angles: 45°, 90° et 135° ont montré que nos solutions aqueuses contenaient un faible pourcentage de produit agrégé dǔ probablement à la présence de groupes acétyles non saponifiés, cette agrégation étant liée à un équilibre thermodynamique très lent à s'établir et dont le coefficient de température est faible, plutǒt qu'à une cinétique de dissolution.Tenant compte uniquement des masses moléculaires trouvées par ultra-centrifugation-diffusion on peut calculer dans le cadre de la théorie de Flory et al. reliant la constante de sédimentation et la viscosité intrinsèque le terme: (S0[η]1/3/M2/3)·1017 qui est à peu près constant et vaut: 13,3 alors que le produit des deux constantes universelles: Φ1/3P-4 est de 3,0·106 au lieu de 2,55 × 106 comme le renseigne Flory. D'un autre cǒté on voit que les relations de Kuhn liant s et DZ au degré de polymérisation Z sont assez bien vérifiées. Toutefois nous estimons que le calcul de l'épaisseur hydrodynamique de la chaǐne comme le font Dialer et al. n'est pas justifié, les extrapolations étant d'une part trop peu précises, le domaine de masse moléculaire investigué d'autre part étant trop étroit. Cette dernière raison ne nous permet d'ailleurs pas de décider entre les deux théories de Kuhn et de Flory, la première disant que la dimension de la pelote statistique “end-to-end” est proportionnelle à M1/2 alors que l'autre veut qu'elle soit proportionnelle à αM1/2.La relation viscosimétrique liant [η] à Mw (ult.-dif.) est donnée par l'équation: \documentclass{article}\pagestyle{empty}\begin{document}$$ [\eta ] = 1,40 \cdot 10^{ - 3} M^{0.60} $$\end{document} pour nos trois fractions.

Notes: In a radical polymerization in which initiation is solely by the addition of an initiator fragment to a monomer molecule, there must be in the polymer one combined initiator fragment for each kinetic chain; analysis of the polymer therefore can lead to a determination of the kinetic chain length. The rate of initiation is equal to the over-all rate of polymerization divided by the kinetic chain length, and so it can be calculated. This new method for calculating rates of initiation is not subject to the uncertainties associated with older methods. Analysis for initiator fragments can be performed accurately if the initiator is labeled with a radioactive isotope; in the work described here C14-α,α′-azo-bis-isobutyronitrile was used. An essential requirement is that the polymer molecules of low molecular weight must not be lost during precipitation of the polymer. Tests are described showing that loss of low molecular weight materials is negligible in most cases and that even when the average molecular weight of the polymer is low and there is an appreciable loss a correction can be made. A correction can also be made for the consumption of initiator during the reaction. The results presented in this paper refer to the copolymerization of butyl acrylate and styrene in benzene solution at 60°. It is shown that for a given monomer mixture the rate of initiation is proportional to the concentration of initiator, and that for each initiator molecule decomposed approximately one reaction chain is started.

Notes: Olefins can only be polymerized by metal halides if a third substance, the cocatalyst, is present. The function of this is to provide the cation which starts the carbonium ion chain reaction. In most systems the catalyst is not used up, but at any rate part of the cocatalyst molecule is necessarily incorporated in the polymer. Whereas the initiation and propagation of cationic polymerizations are now fairly well understood, termination and transfer reactions are still obscure. A distinction is made between true kinetic termination reactions in which the propagating ion is destroyed, and transfer reactions in which only the molecular chain is broken off. It is shown that the kinetic termination may take place by several different types of reaction, and that in some systems there is no termination at all. Since the molecular weight is generally quite low, transfer must be dominant. According to the circumstances many different types of transfer are possible, including proton transfer, hydride ion transfer, and transfer reactions involving monomer, catalyst, or solvent.

Notes: 3,3-Bis(chloromethyl)oxacyclobutane may be polymerized in the presence of powerful electrophilic catalysts, e.g., boron trifluoride; minute traces of water are also necessary for polymerization to proceed. The resulting polyether, poly-3,3-bis(chloromethyl)-oxabutene, is an inert, highly crystalline and insoluble polymer, m.p. 180°, capable of forming oriented films and fibers. The high crystallinity and strong interchain forces are reflected by the complete inconsistency of solution viscosity values measured at 100°. The molecular weights could only be compared by determining melt viscosity values.

Notes: Bei der alkalischen Kondensation von Epichlorhydrin mit zweiwertigen Phenolen entstehen Hydroxyl- und endständige Oxydogruppen enthaltende aliphatisch-aro-matische Polyäther. Die Umsetzung derartiger Reaktionsprodukte mit Dikarbonsäureanhydriden führt zu hochvernetzten wertvollen Massen. Der Härtungsmechanismus wird in der Anfangsphase an einem technischen Produkt und über den ganzen Reaktionsverlauf an geeigneten Modellreaktionen analytisch verfolgt. Es zeigt sich, dass sowohl Diester- wie auch Ätherbrücken als Vernetzungselemente auftreten.

Notes: Die Anlagerung von Äthylenoxyd an Phenol wird quantitativ beschrieben. Die Reaktion geht über die “Anion”-kette. \documentclass{article}\pagestyle{empty}\begin{document}$$ \begin{array}{*{20}c} {{\rm Stufe 1:}} \hfill & {{\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm O}^ \ominus + \to {\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm O}^ \ominus } \hfill \\ {{\rm Stufe 2:}} \hfill & {{\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm O}^ \ominus + {\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm OH} \to {\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm O}^ \ominus + {\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm O}} \hfill \\ {{\rm Stufe 3:}} \hfill & {{\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm O}^ \ominus + {\rm C}_{\rm 2} {\rm H}_{\rm 4} {\rm O} \to {\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm O}^ \ominus } \hfill \\ {{\rm Stufe 4:}} \hfill & {{\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm O}^ \ominus + {\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm O} \to {\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm OH} + {\rm C}_{\rm 6} {\rm H}_{\rm 5} {\rm OCH}_{\rm 2} {\rm CH}_{\rm 2} {\rm O}^ \ominus } \hfill \\ \end{array} $$\end{document} u.s.w. So lange noch Phenol vorhanden ist, wird die Polymerisation bei Stufe 2 unterbrochen und nur Glykolmonophenyläther gebildet.

Notes: The polymerization of activated fibrinogen takes place in two stages. First, the monomer units form intermediate polymers with twice the original cross-section area and about eight times the original length. The polymers have been detected under a variety of conditions between pH 6.1 and 10. The polymerization geometry is believed to be lateral dimerization with a staggered configuration, determined by a pattern of electrical charges. The negatively charged groups, though unidentified, appear to be near histidine residues, as deduced from the dependence of polymerization on pH. The positively charged groups, from this and other evidence, appear to be α-amino groups. Second, the intermediate polymers unite to form the strands of the fibrin network. This association appears to involve nonpolar groups, and the width of the final strands, unlike that of the intermediate polymer, depends markedly on the net charge as determined by the pH.

Notes: The principle of the method of Paneth and Hofeditz of studying gaseous free radicals has been employed for chain reactions in liquid monomers. The half-life of a photochemically initiated polystyrene free radical has been found to be 0.088 ± 0.015 second. A simple extension of the technique should also give absolute values of the propagation rate constant and the chain transfer constant.

Notes: The preparation of poly-p-xylylene, , in 24-26% yield, by pyrolysis of p-xylene, is described in detail. The nature and amount of by-products of the pyrolysis were determined. The physical appearance and the following properties and reactions of the polymer are described: x-ray diffraction, crystallinity, optical constants, infrared absorption spectrum, degradation by autoxidation in solvents and by pyrolysis, dielectric constant and loss, sulfonation and chlorination. The significance of this data is discussed relative to an understanding of the mode of formation and the structure of the polymer.

Notes: The second order transition temperatures of three different cures of natural rubber have been studied as functions of elongation by observing length dependence on temperature. This transition temperature (Tm) decreases with increasing applied force, and at any given force increases with increased crosslinking; moreover the slopes of the Tm vs. force curves become less steep with increased crosslinking. The results are in agreement with the following propositions: (1) that transitions are caused by the onset of rotations; (2) that extension of the polymer makes the onset of such rotations easier, thus lowering Tm; (3) that increased crosslinking hinders rotation so as to increase Tm; and (4) that increased crosslinking diminishes the effect of a given force on Tm. The hypothesis of rotation is also discussed in connection with the effect of swelling agents on the second order transition.

Notes: For the viscometric determination of the molecular weight of a flexible linear high polymer, a very “poor” solvent in which the osmotic slope constant B is zero (i.e., a so-called “ideal” solvent) has several advantages over the usually preferred good ones. For example, shear effects that are very troublesome with very high polymers in good solvents become negligible or easily manageable. Moreover, in an “ideal” solvent, the “contents” K and a in the equation relating [η] and M really are constant over a very wide range of molecular weights and, since a always has the value 0.50, are more easily determined. Because the advantages seem to outweigh considerably the disadvantages, the use of an “ideal” solvent should be given careful consideration, particularly when the molecular weights are very high or cover a wide range.

Notes: Six amphoteric copolymers of different composition of 2-vinylpyridine and methacrylic acid were investigated. The specific viscosities of the copolymer solutions exhibit a pronounced minimum at the isoelectric point and the spectrometric titration of the pyridinium groups shows a pronounced jump in pH at the isoelectric degree of ionization. A theory of the polyampholyte behavior, based on the shape changes of the macromolecules and the field energy of the ionized groups, is developed and compares satisfactorily with the experimental results. The theory permits inter alia the evaluation of the intrinsic dissociation constants of the monomeric units and the determination of the isoelectric points from copolymer composition.

Notes: (1) The electrostatic internal energy of a solution of rodlike, ionized polymolecules is calculated by an integration which makes use of the molecular potentials evaluated previously. (2) The electrostatic free energy is calculated by a charging process for which the reference state is a discharged solution of the same concentration as that of the charged solution. (3) A series of graphs is presented for the numerical evaluation of the internal and free energies of salt-free polyelectrolyte solutions as a function of concentration, degree of ionization, and temperature. (4) The osmotic pressure of stretched polyelectrolytes is calculated from the free energy expression. The calculated osmotic coefficients are practically independent of molecular weight and polyelectrolyte concentration, and are determined by the degree of ionization. A comparison with the measurements of Kern on salt-free polyacrylic acid at higher degrees of ionization (for which the macromolecules are stretched) gives a very satisfactory agreement. (5) An expression for the light scattering by polyelectrolyte solutions is derived from the equation for osmotic pressure and discussed briefly.

Notes: The electrolytic dissociation of several polymeric acids and bases in aqueous solutions has been investigated. The potentiometric behavior is well described by the following equations, For polyacids: \documentclass{article}\pagestyle{empty}\begin{document}$$ p{\rm H} = pK_0 - \log \frac{{1 - \alpha }}{\alpha } + 0.4343\frac{{\varepsilon \psi _0 }}{{kT}} $$\end{document} and for polybases: \documentclass{article}\pagestyle{empty}\begin{document}$$ p{\rm H} = pK_0 - \log \frac{\beta }{{1 - \beta }} - 0.4343\frac{{\varepsilon \psi _0 }}{{kT}} $$\end{document} pK0 is the intrinsic dissociation constant of the monomeric unit, α and β are the degrees of ionization of the polyacid and the polybase respectively, ψ0 is the electrostatic surface potential of the polyion. It is shown that ψ0 is equal to (1/∊) (δFe/δv) for polyacids and (1/∊) (δFe/δζ) for polybases where Fe is the electrostatic energy of the polyion and v or ζ the number of negative or positive ionized groups respectively. Equations for the calcualtion of ψ0 in the cases of randamly kinked and stretched polyelectrolytes are given and discussed. As the potential ψ0 can be obtained independently from electrophoretic measurements, the above equations correlate potentiometry and electrophoresis. The potentials of polymethacrylate ions were calculated from theory and obtained from electrophoretic and potentiometric measurements. The potentials obtained by the three methods agree within 3% thus justifying the use of the combined potentiometric and electrophoretic measurements for the evaluation of pK0. Application of this method to the potentiometric analysis of pectic acids gave good agreement with experiment and lead to pK0 = 3.40. Combined potentiometric-electrophoretic analysis for polyaspartic acid gave pK0 = 3.53 and for polylsine pK0 = 10.44.

Notes: A new theory of strong polyelectrolyte solutions based upon the Poisson-Boltzmann equation is presented. Assuming that the ratio of the effective charge of the macro ion to its original charge is very small, the Poisson-Boltzmann equation is solved without adopting the Debye-Hückel approximation. As a result of the calculation, the effective charge of the actual coiled macro ion with the strongly dissociative groups was found small enough to justify this assumption for the solutions of varying concentration over wide range. Moreover, the free energy, and consequently the chemical potential of the components, of the polyelectrolyte solution with or without simple salt are calculated. The idea of “ion fixation” is theoretically introduced as convenient for representing the state of the polyelectrolyte solution. The theoretical results obtained above are quantitatively compared with experimental data with very good agreement.

Notes: The viscosity of a partially (60.8%) quaternized polyvinylpyridine with n-butyl bromide has been investigated in dilute-water and sodium chloride solutions, in a rotation (Couette) viscometer, at low gradients of flow. It was possible to extrapolate the ηsp/c against concentration plot in water by working at very low concentrations of the polymer. At about 5 × 10-5 g./ml. the curve reaches a maximum and decreases sharply upon dilution to about one-sixth the value at the maximum. The shape and size of the equivalent ellipsoid corresponding to the 60.8% polyvinylpyridinium bromide (DP = 7660) ions was estimated from the limiting viscosity number ([η] = 9500 ml./g.) and birefringence (extinction angle) data. The length of the stretched molecule was estimated to be 7420 A., corresponding to 〈 half the hydrodynamic length of the extended macromolecule. Extrapolations in sodium chloride solutions have been obtained at constant concentrations (up to 10-3 M) of the simple electrolyte. Small amounts of added simple electrolyte decrease the viscosity numbers in solutions at finite concentrations of the polymer to a large extent, whereas the limiting viscosity numbers are affected to a far smaller degree. This phenomenon has qualitatively been attributed to the pronounced decrease in the intermacromolecular electrostatic interactions at finite concentration of the polymer upon the addition of a relatively small amount of mobile electrolyte; at the same time the intramacromolecular interactions are affected to a much smaller extent.

Notes: It is shown that ηsp/c for a polystyrene fraction (M̄v = 250,000) in toluene decreases approximately linearly as the concentration is lowered from 1.0 to 0.1 g./100 ml. and then increases to a maximum at 0.001 g./100 ml. as the concentration is lowered still further. This increase in ηsp/c with dilution is a new effect which we ascribe to the expansion of polymer coils as well as to the disentangling of entire polymer molecules once the concentration is lowered to where there is ample room in the solution for each polymer molecule. The new techniques employ a viscometer with a flow time of 3893 seconds for toluene, special filtering of the solutions, and prolonged agitation of the solutions after each dilution. We present data to show that ηsp/c is time dependent at concentrations below 0.1 g./100 ml.

Notes: A simple and exact method is presented for the calibration of light scattering photometers in absolute turbidity units employing du Pont Ludox as the calibration medium. It is shown that previous attempts to employ Ludox as a standard took no cognizance of the relatively high scattering power of this substance in relating τ to I90, and hence results considerably in error were obtained. To check the validity of the calibration, molecular weights were run on the standard Cornell polystyrene in toluene and MEK, and on the I. U. C. sample III polymer in MEK at both 4358 and 5461 A. The results obtained show excellent internal consistency as well as agreement with published data.

Notes: A viscoelastic material when extruded rapidly through a short capillary or spinneret may exhibit an effective viscosity which is smaller than the usual or zero shear rate viscosity by a factor of several hundred. An equation is derived which expresses the effective viscosity as a function of the time the material spends in the spinneret (transit time) and the distribution function of Maxwellian relaxation times. It is assumed that the mechanical properties of the material may be represented by a generalized Maxwell model. Effective viscosities observed when a 25% cellulose acetate solution in a 96:4 (by weight) acetone:water solvent is extruded through a spinneret with radius 0.006 cm. and effective length 0.0186 cm. are given. The relaxation distribution function for the cellulose acetate solution is calculated from the dynamic viscosity data of Philippoff. From the distribution function and values of the transit time, effective viscosities are calculated and found to differ from the experimental values by -26 to 60%. In view of the fact that the effective viscosities are smaller than the zero shear rate viscosity by factors ranging from 145 to 10.8, the agreement between calculated and experimental values is quite satisfactory.

Notes: The modification of the amorphous/crystalline ratio in polyethylene terephthalate by copolymerization with glycols or dibasic acids usually results in a lowering of the degree of crystallinity and of melting point, and impaired physical properties. A consideration of the molecular constitution of silk fibroin suggests a way of modifying the molecule to produce an increase in the amorphous content of the polymer with retention of the crystallite structure. In the silk fibroin molecule it is significant that two lengthy segments (about 170 A. long) as contrasted with the rest of the molecule carry bulky side chains which prevent their entry into the crystalline regions of the fiber. The fact that these segments are accommodated in the amorphous regions suggested by analogy that one or two linear molecules of 100-200 A. in length might be successfully incorporated in the polyester molecule with a probable improvement in such physical and chemical properties as flexibility and dyeability. The modifying component must have reactive end groups, be thermally and chemically stable under polymer-making conditions, and should have water-sensitive groupings. Polyoxyethylene glycols (Carbowaxes) of molecular weight 1000-6000 satisfy these conditions and with polyethylene terephthalate give high melting “block copolymers” that can contain as much as 30% by weight of the modifying component. The dyeability, moisture regain, and flexibility (measured by determination of the second order transition point) are all materially increased, while at the same time the tenacity and extensibility are unaltered. Since the molecular proportion of the modifying component is small (less than 2% of the repeating units are substituted), there is only a small reduction in melting point. This indicates little alternation in the crystallites, a fact confirmed by the substantially unaltered x-ray photographs. That the copolymers are not blends but are true compounds is shown by the failure to remove the modifier by continuous extraction with solvents and by the incompatibility of polyoxyethylene glycols and molten polyethylene terephthalates. Absence of fragmentation of the modifying components on entering the polymer chain is shown by its almost quantitative recovery from the alkaline hydrolyzate of the copolymer. Despite their excellent physical properties these copolymers are not technically attractive as fibers because of their instability to ultraviolet light (and to strong sunlight). Furthermore, exposure of the dyed fibers to ultraviolet light shows that the rate of fading of dye has been seriously increased by the introduction of the third component into the molecule. Polyoxyethylene glycols may also be incorporated as side chains in the copolymer molecule to give similar high-melting copolymers with improved dyeability and retention of physical properties. Copolymers of polyoxydecamethylene glycol and polyethylene terephthalate show good physical properties but no improvement in dyeability, probably because the “blocks” introduced are deficient in ether-oxygen atoms and hence lacking in hydrophilic character. It is suggested that this novel type of copolymer is probably fairly widespread in the field of proteins, and is not confined to silk fibroin. For example, some of the physical properties of collagen (and of gelatin) are best explained by assuming that certain chain segments, because of their amino-acid composition, have a strong crystallizing tendency.

Notes: The flow and retarded-elastic behavior of four polyisobutylene specimens (M̄w 1.09 × 104 to 8.54 × 104), measured in a concentric cylinder rotational viscometer, are reported. Under the conditions investigated the non-Newtonian flow behavior can be represented by Ferry's equation. The logarithm of the viscosity η varied linearly with the reciprocal of the square of the absolute temperature. The time-scale for retarded elasticity was found to vary with temperature in the same way as the viscosity. The normalized retarded elasticity functions at temperatures corresponding to unit viscosity are substantially identical. The time corresponding to a normalized retarded elastic compliance of 0.5 is about 10-5 η second when η is in poises. The reciprocal steady state shear compliances 1/J and internal shear moduli Gi in Ferry's equation are of the same order of magnitude for each polymer. The retardation time function L(ln τ) is calculated for one of the polymers, and then the dynamic response; these results are in good agreement with dynamic measurements on this material. From a consideration of the stress relaxation behavior of high molecular polymers, it is pointed out that there must exist another retarded elasticity mechanism, the time-scale of which depends only on temperature and not on molecular weight. This second mechanism is masked in the reported experiments on low molecular polymers.

Notes: The kinetics of the reaction between natural rubber hydrocarbon and sulfur monochloride is investigated in dilute hydrocarbon solution by the dilatometric technique. Control experiments with trilaurin and triolein show that the reaction requires unsaturated linkages in the compound to be cold-vulcanized. The extent and rate of the nonaccelerated reaction with rubber is shown to depend strongly on the nature of the solvent. Moreover, the nonaccelerated reaction is autocatalytic in nature, and exhibits kinetics that are first order with respect to sulfur monochloride. The accelerating effects, on the reaction, of Butyl 8, mercaptobenzothiazole, dibutylammonium dibutyl-dithiocarbamate (DBA), and methanol are investigated and it is shown that, in the presence of sufficient Butyl 8 or DBA, the autocatalytic nature of the reaction is changed to one that is kinetically of pure first order. The accelerated (Butyl 8) reaction is found to be first order with respect to sulfur monochloride. The accelerated reaction is further shown to be first order with respect to DBA and second order with respect to methanol. A free radical mechanism is proposed for the nonaccelerated reaction, involving attack by the intermediate $ \mathop {\rm S}\limits^ * {\rm \bond S \bond Cl} $ at the double bonds of the rubber molecule. It is suggested that accelerators function by reacting with sulfur monochloride to produce the active intermediate $ \mathop {\rm S}\limits^ * {\rm \bond S \bond Cl} $.

Notes: A comprehensive study of the dynamic mechanical and dielectric properties of acrylic polymers (polymethyl methacrylate, polymethyl-α-chloroacrylate) has been made; these two properties were found to be intrinsically correlated; results are given in graphic form. The hypothesis is proposed that each of several mechanical and dielectric dispersion regions found in a given polymer is associated with a definable structural feature, i.e., a group of atoms, in the polymer, such that each group gives rise to a mechanical dispersion and, if polar, also to a dielectric dispersion in the same temperature and frequency region; it should also be possible to trace the same dispersion from one polymer to another, provided they all contain the same group.

Notes: Independent means of assaying free radical copolymerization polarity (e) values from ionic copolymerization data are outlined. Interpretation of ionic (carbanionic and carbonium) copolymerization data in general in the light of these same e values is discussed. An extension of Wall's equation: \documentclass{article}\pagestyle{empty}\begin{document}$\frac{{d[{\rm M}_1 ]}}{{d[{\rm M}_2 ]}} = \alpha \frac{{[{\rm M}_1 ]}}{{[{\rm M}_2 ]}}$\end{document} to allow prediction of ionic copolymerization reactivity of untested combinations is offered. For carbanionic systems: \documentclass{article}\pagestyle{empty}\begin{document}$\frac{{d[{\rm M}_1 ]}}{{d[{\rm M}_2 ]}} = \frac{{P_1 [{\rm M}_1 ]}}{{P_2 [{\rm M}_2 ]}}$\end{document} where P1 and P2 are empirical functions of the polarity e of Alfrey and Price. For carbonium systems: \documentclass{article}\pagestyle{empty}\begin{document}$\frac{{d[{\rm M}_1 ]}}{{d[{\rm M}_2 ]}} = \frac{{N_1 [{\rm M}_1 ]}}{{N_2 [{\rm M}_2 ]}}$\end{document} where N1 and N2 are different empirical functions of the polarity e. Advantages and limitations of the technique are discussed.

Notes: The hydrodynamic properties of native and urea-denatured fibrinogen have been investigated, primarily to examine further the suggestion, based on a consideration of data for horse serum albumin, that urea denaturation may involve swelling instead of increased asymmetry. A sedimentation-diffusion and also a light scattering molecular weight determination at the isoelectric point indicate that 6 M urea causes neither splitting nor aggregation of the native protein in the denaturation process. The observed increase in the intrinsic viscosity and frictional coefficient upon denaturation can be interpreted in terms of an equivalent hydrodynamic ellipsoid of approximately the same shape but of a volume which is approximately 1.7 times that for the native protein. The effective volume appears to be slightly dependent on pH with a minimum at the isoelectric point. It thus appears that the urea denaturation of bovine fibrinogen, like that of horse serum albumin, may involve swelling. There is no indication in the case of either protein that increased asymmetry is involved in accounting for the frictional behavior of the denatured substances.

Notes: Using a simple statistical model, the probability of intramolecular reaction is calculated for the polymerizing diallyl phthalate molecule. The calculation is based on the assumption of the free rotation of bonds and a restriction of the chains considered to 9 and 11 links. Allowance is made for the different types of terminal structure produced during the reaction. The result agrees with the experimental work of Simpson in that an appreciable probability is found. (Theoretical 31%, experimental 41%, saturated groups). It is probable that the accuracy of the results obtained has been increased by reason of the fact that different imperfections in the model affect the result in opposite senses.

Notes: The effect of exposing long chain polymers to high energy radiation is either to produce crosslinking or chain degradation. Changes in some of the properties are outlined. The formation of gel in many polymers offers a possibility of obtaining information as to the initial molecular weight distribution. Results are given of a mathematical analysis of the amount of gel formed for various degrees of crosslinking. From the shape of the gel crosslinking curve the ratio of z average, z + 1 average etc., to weight-average molecular weight can be deduced. Formulae for the changes in the molecular weight of the sol are also given.

Notes: Reaction curves for the reaction of cellulose with acetic acid and water were studied. This reaction was found to be slow and severely limited in extent of reaction. An analysis by means of reaction kinetics equations of this limited reaction led to the following suggested reaction mechanism: (a) The larger fraction of cellulose hydroxyl groups - 88% in the particular samples of cellulose investigated - cannot be acetylated because the mutual hydrogen-bonding between these groups imposes an energy barrier to reaction. This causes the equilibrium constant for the reaction of these groups to be highly unfavorable toward acetylation. (b) Part of the remaining hydroxyl groups (those which do react) react very slowly with a reaction rate apparently dependent on the rate of diffusion of acetic acid into the cellulose fibers. These hydroxyl groups are apparently unassociated hydroxyl groups buried within the cellulose fibers. (c) The remaining hydroxyl groups apparently react according to the kinetics of homogeneous acetic acid acetylation and thus must be in freely accessible locations, such as on the fiber surfaces.

Notes: The extent of branching in polystyrene is attributed to a polymer transfer step occurring during polymerization. In this process a radical abstracts a hydrogen atom from along a chain which then adds monomer at the site of the abstraction. The rate of this process should be decreased if the hydrogen is replaced by deuterium, and consequently deuterated monomers should polymerize to form polymers less branched than those from the nondeuterated monomer. Polymers of α- and β-deuterostyrene were synthesized and thier intrinsic viscosity and molecular weight by light scattering determined. In the case of the α-deuterostyrene, the polymer was also fractionated and measurements were made on the fractions. The data for the deuterated styrenes fit quite closely the same relationships as a normal styrene sample prepared simultaneously and under the same conditions, i.e., 70°C. and without catalyst. The results indicate, therefore, that branching is quite small in polystyrene prepared under such typical conditions. A check of the isotope effect on the transfer process was made utilizing S-deuterobutyl mercaptan. A value of 4.0 was obtained at 60°C. for the relative rate of transfer with butyl mercaptan to that for the deuterated mercaptan.

Notes: It is possible to obtain a polyampholyte characterized by the presence of primary amine and carboxylic functions by a method based on the mutual reaction of functional groups along the polymeric chain. The great advantage of this method is the production of copolymers of a new type, from which the internal structure is well defined. In the present case the method is based upon interaction of an acyl chloride unit with a neighboring isocyanate function; these isocyanate functions have been introduced into the chains by two different methods, the Curtius reaction (sodium azide on polyacroyl chloride) and the Lossen reaction (hydroxylamine base on polyacroyl chloride). The solvents used were dioxane and dimethylformamide; the reactions were performed at ebullition. Higher boiling solvents yield an increasing amount of insoluble material. Both syntheses give end-products with the same properties. The structure of the polymers has been established from conductometric and potentiometric titration curves and also from nitrogen analysis. It was found that the interactions produce the formation of rings along the chain, and that these interactions are limited, as can be foreseen from statistical reasons; the residual groups remain free and become carboxylic functions after hydrolysis, or they react further and are transformed into amino functions. The final products are to be considered as copolymers of vinylamine and acrylic acid with a predominant alternate structure, and in which a given amount of amino groups have reacted with a neighboring acid function yielding lactam rings. However, these pyrrolidone units may be easily opened by alkaline hydrolysis, yielding thereby a polymeric chain with free amino and carboxylic functions, from which the proportions are approximately equivalent at high nitrogen content (12.5-13% N2). At lower nitrogen content the proportion of free carboxylic functions predominates; e.g., at 9.8% N2 there is an excess of 24% acidic functions. Determinations before and after hydrolysis allow the establishment of the internal structure of the copolymers; the proposed structure has been confirmed by benzoylation and deamination reaction and analysis of the benzoylated and deaminated copolymers.

Notes: Rates of adsorption of polystyrene on to charcoal from methyl ethyl ketone solutions are influenced by water present in the solvent causing resting periods. These resting periods disappear when water-free solvent is used. The type of adsorption isotherm and molecular weight relationship are not influenced by the presence of water. The temperature coefficient for rate of adsorption is small.

Notes: A method for fractionating gelatin based on the solubility behavior of gelatin/detergent complexes is described. The method is practical and convenient both for determining molecular weight distributions and for preparing gelatin fractions. It is shown that fractions of equal reduced viscosity, and hence molecular weight, derived from gelatins of similar isoelectric points may still differ in important respects, thus confirming the conclusions of Pouradier and Venet, who prepared fractions by a different method of fractionation. It is established that the rigidity of gels formed from the gelatin fractions is independent of molecular weight, at least at 5.5 g./100 ml. concentration. There is some indication that, for the lowest molecular weight fraction, a slight variation of rigidity with molecular weight is occurring. Some other structural feature, at present unidentified, must be associated with the mechanism of gel formation.

Notes: The irreversible fixation of vegetable tannins (mimosa) by collagen and esterified collagen, as well as by a hydrated polyamide, has been investigated. The polyamide possesses a marked affinity for the vegetable tannins and binds them irreversibly, proving that the peptide linkages function as binding sites for vegetable tannins. This fixation is independent of pH value of the system in the pH range 2-8. The same independence is shown in the fixation of tannins by collagen from solutions containing sodium chloride which prevents the swelling of collagen. The typical fixation curve of vegetable tannins by intact collagen is highly pH-dependent. In this instance the tannin fixation is directly related to the degree of swelling of collagen as a function of the pH value of the system. This is due to the fact that the degree of swelling of the protein governs the number of coordination-active peptide bonds present in collagen for the fixation of tannins. Esterified collagen, in which the major part of the potential hydrogen binding sites are free to react, fixes large amounts of tannins independently of the hydrogen-ion concentration of the system in the pH range 2-7. The rapid drop in fixation of tannins at pH values 〉8 is due to the ionization of phenolic groups, leaving fewer hydrogen bonds available on the tannin molecule. Evidence is presented in support of the view that the main reaction of polyphenolic tannins of the major type represented by mimosa tannins consists in coordination of a polyphenolic molecule to peptide bonds of adjacent protein chains, probably by means of hydrogen bonds. This multipoint attachment will explain the stabilization of the protein lattice effected by the tanning agent.

Notes: The kinetics of reaction between amino acids and lower aldehydes (acetaldehyde, propylaldehyde) was followed by the Van Slyke technique and a quantitative chromatographic method. In a narrow range of pH (pH 6-7), the reaction was found to be bimolecular. Graphically computed bimolecular kinetic constants are presented for a certain number of amino acids reacting with acetaldehyde. Under certain conditions (for instance, tryptophane in acetic acid solution with acetaldehyde) the reaction rate was slowed down to trimolecular. At some acid or alkaline pH values the exact order of the reaction could not be determined (it was not of the first, second, or third order). Except for tryptophane, which reacted more rapidly in acid media, the amine-aldehyde combination rate was accelerated by rising pH. The combination rate of histidine is directly proportional to the acetaldehyde concentration, the proportionality factor being unchanged with increasing the pH from 3.00 to 6.20. In some cases (for example, propylaldehyde with lysine) the amino nitrogen content reached a minimum after 10-20 minutes, and then rose to attain even the initial value. Specific viscosity did not change (tryptophane), or else decreased (lysine, arginine, histidine) during the acetaldehyde-amino acid reaction. In acetaldehyde-NaOH or acetaldehyde-morpholine mixtures the viscosity was unaltered even when the solution became rapidly turbid and aldehyde-resin precipitated. It was possible to separate the reaction products obtained during the formation of aldehyde-resin and aldehyde-amino acid interaction by the method of paper electrophoresis. The fluorescent patterns were characteristic for each amino acid. Most of the amino acids showed 3-6 spots of different fluorescent color. This rendered probable the hypothesis that the same aldehyde condensation products are formed in amino acidaldehyde mixtures as in alkali-acetaldehyde solution.

Notes: With the development of the ultracentrifuge by Svedberg there was provided a group of methods for the determination of solute molecular weight and of distribution of molecular weights in proper solutions. In addition to the sedimentation equilibrium and the sedimentation velocity experiments, there are other closely related molecular kinetic phenomena which, when taken together, form a collection of very useful tools in an area of macromolecular chemistry.The principal past use of the ultracentrifuge has been in the determination of the molecular weight and the homogeneity of proteins. In this report the attempt has been made to point the way for concerted action in the return to the original problem-that of investigating the dispersity of macromolecular and other colloidal solutions. Among other things, there is proposed in outline a combination of the sedimentation velocity and sedimentation equilibrium experiments to provide mass distribution data in macromolecular systems. While the main emphasis is devoted to the theory of the sedimentation methods and their unique usefulness to this end, there have been presented shorter discussions of diffusion and osmotic pressure as such and in their relationships to the sedimentation problems.Recognition is also made of the fact that the optical systems for the study of the redistribution of the components in the diffusion and sedimentation cells are now in a state of change, with a rapid adaptation of several interference methods to take the place of the more classical refractometric schemes. The change is being made in the interest of a greatly enhanced accuracy, even to the point that diffusion behavior in systems which contain two solutes can properly be observed.

Notes: The bacteriophages (bacterial viruses) are the largest biologically active agents having known dimensions and particle morphology which have been prepared in a homogeneous state. Because all the bacteriophages have an appendage or “tail”, they offer an interesting system for study in the analytical ultracentrifuge in comparison of the results of direct and indirect methods for estimation of particle size and shape. The sedimentation behavior of phages T5, T6, and T7, all differing in size and morphology, has thus been investigated. Although, under certain conditions, the three viruses sediment with a single sharp boundary, T6 appears to undergo aggregation to form a dimer at neutral pH. The sedimentation rate of the phages is little affected by concentration and is uninfluenced by the centrifugal field, thus indicating the absence of interaction or of particle orientation due to the peculiar morphology. A comparison of estimates of the particle size and weight based on molecular-kinetic constants, electron micrograph dimensions, and unit infectivity yields a good correlation among the results of the direct and indirect physical methods for the quasispherical particle of T7, satisfactory agreement for the large tadpole-shaped particle of T6, but considerable discrepancy for the sperm-shaped particle of T5. It is suggested that the dimensions of T5 based on early electron micrographs are in error. Despite their large size and unusual shape the bacteriophages are amenable to physicochemical study, and each type is as uniform in molecular-kinetic properties as are molecular proteins.

Notes: This report presents some general applications of a new type of ultracentrifuge cell, called a synthetic boundary cell, in which a sharp, stable boundary is obtained by layering one solution over another more dense solution while the ultracentrifuge is in operation. Since such a boundary between a solvent and a dilute solution of a low molecular weight solute can be formed in the center of the cell, the complications encountered at the meniscus in conventional ultracentrifugation by the high diffusion and low sedimentation rate of the solute are obviated. By this technique the sedimentation velocity method has been extended to substances with molecular weights as low as 350. Sedimentation constants of a number of low molecular weight materials such as fraction A of insulin (molecular weight 3000), vitamin B12 (molecular weight about 1500), β-dextrin (molecular weight 1134), and sucrose (molecular weight 342) have been determined. The cell has also been used to form a boundary between solutions of two different concentrations of the same macromolecule and differential sedimentation constants have been obtained. The relationship between these differential sedimentation constants and those obtained for either of the two solutions when studied alone is discussed. Application of the cell to the determination of hydrodynamic volumes of sedimenting components is described. Measurements are made of the backward flow of solvent by the use of an indicator boundary formed by layering a virus solution over another virus solution containing an additional component, such as sucrose or a protein, which acts as an indicator. In addition, the cell was used in a preliminary investigation of some fundamental problems in ultracentrifugation such as the sedimentation of slowly sedimenting materials in the presence of more rapidly sedimenting components, the analysis of equilibrium systems such as insulin and chymotrypsin, and the role of convection.

Notes: The formulas used for calculation of diffusion coefficients in free diffusion are stated. The calculations request the 0th, first, and second moments of the curve to be calculated. This is usually made by calculation of moments of segments of the figure between the curve and the base line, followed by summation.It is proposed to replace this rather laborious procedure by the use of an integrator. A survey is given on the theoretical background and the principles for such instruments. Some equations are stated for the type of instrument used in these investigations. From these equations it is possible, by inserting the values in the formulas used for the calculation of diffusion coefficients, to express the latter for a certain curve as a function of the rotation of the three integration rolls in the instrument. The relative influence on the final result for these integration rolls is considered. For one of the rolls this can be shown to be insignificant, when the moment axis is chosen very near the central axis of the curve. Our experience has shown the standard error in a normal measurement to be 2 × 10-3 and 3 × 10-3 of a revolution for the two other integration rolls. Some curves are given which show the requests one must put on the relative number of rotations for these rolls to make certain that the relative standard error, introduced by the integrator, will not exceed certain values on the final result. The curves are drawn for values from 2 to 0.1%.From a known Gaussian distribution a set of diffusion curves is drawn. The diffusion coefficient is calculated from these curves both by the usual method and by the integrator. The results obtained by the integrator compare well with those by the usual method if the peaks are not drawn too narrow.

Notes: Semipermeable membranes used for osmotic pressure measurements are usually made from collodion or from regenerated cellulose or from other cellulosic materials. Such membranes are readily attacked by corrosive solvents, they are easily oxidized, and they can be used for only a few hours at high temperatures. To overcome these difficulties new noncellulosic membranes have been developed. The preparation of a polyvinyl butyral membrane and of a Kel-F (polychlorotrifluoroethylene)membrane is described. The data for typical osmotic pressure measurements using the new membranes are presented. The Kel-F membrane can be used for measurements in all common organic solvents as well as for solutions of cellulose in solvents such as cupriethylene diamine and cuprammonium hydroxide. It is also suitable for high-temperature osmotic pressure measurements.

Notes: Methyl methacrylate was copolymerized with small amounts of methacrylic acid or dimethylaminoethyl methacrylate. The molecular weight of the basic copolymer calculated from osmotic pressure data in butanone and benzene gave consistent results. The molecular weight of the acidic copolymer was obtained from osmotic pressures of pyridine solutions, but in butanone and particularly in benzene strong molecular association was observed. Osmotic pressures of mixtures of the two copolymers in butanone at 30.2 and 50.1 and in benzene at 49.7°C. were determined. The reduced osmotic pressure plots were linear but indicated the persistence of molecular associations to the highest dilutions at which osmotic pressures could be measured. A thermodynamic analysis of the data showed that under certain conditions the activity of one or the other polymer component decreases with increasing concentration of the mixture.

Notes: A method is described for determining the distribution of molecular weights of polyvinylpyrrolidone (P.V.P.) by measurement of the turbidity produced in aqueous solution by varying concentrations of sodium sulfate. Using this method, the acetone-water method of fractionation is shown to be unsound due to inhomogeneity of the fractions obtained. This latter method is, however, of value in the preparation of P.V.P. of narrow molecular weight ranges by repeated fractionation. The distributions of molecular weights of typical samples of P.V.P. used in the plasma substitute, Plasmosan, are given. Less than 5% by weight of the molecules possess a molecular weight greater than 100,000. The reproducibility and stability to autoclaving of this polymer are shown to be satisfactory.

Notes: Die besten Methoden zur Synthese von Kohlenhydrat-Eiweissverbindungen, in denen beide Komponenten in biologisch möglicher Art kovalent miteinander verbunden sind: (1) Mono-saccharid- oder Poly-saccharid-carbonsäuren werden über ihre Azide peptidartig an die ε-Aminogruppen der Lysinreste in Proteinen gebunden. (2) 1-Cyanamidoverbindungen von Monosacchariden kondensieren sich mit den freien Aminogruppen (siehe 1) der Proteine zu Zucker-guanyl-proteinen. (3) 1-Alkyl-iso-thioharnstoffderivate von Mono-sacchariden geben (wie bei 2) mit Proteinen Zucker-guanyl-proteine. Es reagieren nach Verfahren (2) und (3) weniger als 50% der ε-Aminogruppen der Lysinreste in den Proteinen. Dies dürfte auf eine Blockierung der Aminogruppen durch Carboxyl- u.a. Gruppen zurückzuführen sein. Durch Umsetzung von Poly-saccharidproteinverbindungen (nach Methode 1 erhalten) mit Ölsäurechlorid werden Kohlenhydrat-oleyl-proteine synthetisiert, in denen die Oleyl-reste an die Protein-reste, nicht an die Kohlenhydratreste, gebunden sind. Sie enthalten die Bausteine von Lipoiden in kovalenter Bindung. Salzartige Kohlenhydrat-Eiweissverbindungen werden aus D-Glucose-6-schwefelsäure und Xylan-schwefelsäure mit Proteinen erhalten. Die Zusammensetzung der Salze entspricht dem Äquivalenzverhältnis zwischen den Schwefelsäure-resten der Kohlenhydrate und den basischen Aminosäuren der betreffenden Proteine. Die sich daraus errechnenden Äquivalentgewichte der Proteine sind von der gleichen Grösse wie die nach anderen Methoden gefundenen.

Notes: A radial distribution method for interpreting diffuse x-ray diagrams of liquids has been utilized and further developed for an approach to the solution of structural problems of unoriented specimens of chain polymer substances. The principles of the technique have been given. Experimental distribution curves, indicating the atomic distance distributions have been calculated for the following chain polymers: polyvinyl acetate, polyvinyl alcohol, polystyrene, polyhexamethylene adipamide, polymethyl methacrylate, regenerated cellulose, and alginic acid. For the structure interpretation some of the experimental distribution curves are directly compared with theoretical distribution curves calculated from the atomic distances in measured out structure models, which have been built up on a scale of 1 A. equal to 10 cm. by means of a molecular model building set. From the results obtained, the technique seems to be well suited for structure investigations of unoriented samples of polymer substances.

Notes: A pyrolytic dehydrogenation technique originally proposed by Szwarc has been employed for the preparation of polyhydrocarbons from p-xylylene, pseudocumene, and durene. With particular emphasis on poly-p-xylylene, the structure and physical properties of the polymers were investigated. Poly-p-xylylene may be obtained in two modifications: a transparent form and opaque form. The transparent form of poly-p-xylylene exhibits uniaxial, negative birefringence. The opaque form on purification by chloroform extraction melts at 412°C. Heat treatment of either modification appears to result in an irreversible, polymorphic transition. Poly-p-xylylene may be stretched at temeratures above 150°C. to reveal a well-defined x-ray fiber diagram, having an identity period of one. Sulfonation of poly-p-xylylene yields a product having one sulfonic acid group per benzene ring. The product swells anisotropically but does not dissolve in water. This observation, as well as the observation that the rate of dissolution of poly-p-xylylene in high boiling solvents is dependent upon the presence of oxygen, suggest that the polymer is crosslinked to a small but finite extent. The polymer derived from pseudocumene is also crosslinked but contains up to ca. 21% of a chloroform-extractable component. The number-average molecular weight of the chloroform soluble component is 23,900.

Notes: A volume dialometric study of the crystallization behavior of polychloroprenes made at -40°, 10°, and 40°C. has shown that the melting point of the crystalline phase in these polymers is an inverse linear function of polymerization temperature. Polychloroprene made at -40°C. melts at ca. 65°C., while conventional 40°C. neoprenes melt at ca. 40°C. Comparison of this data with the melting point depression observed in a chloroprene/methacrylonitrile copolymer and in polychloroprene/diluent mixtures has made possible calculations which confirm earlier hypotheses that neoprenes have a highly regular structure. Commercial neoprenes made at 40°C. are calculated to consist of 80-85% of the trans-2-chloro-2-butylene units which result from trans-1,4 polymerization of chloroprene. Densities determined for crystalline and amorphous neoprenes have been used to calculate the degree of crystallinity of these polymers, and this information has made possible calibration of the infrared crystallization-sensitive bands, for use in measurement of degree of crystallinity. The heat of fusion of the crystalline phase of neoprenes has been found from diluent data to be 22.7 ± 2 calories per gram.

Notes: A study of the infrared absorption spectra of polychloroprenes made at temperatures ranging from -40 to 100°C. has made possible identification and estimation of the major structural features of these polymers. It is confirmed that 1,4 polymerization of chloroprene accounts for the greatest part of the structure of all neoprenes, ranging from 99% in -40°C. polymers to ca. 84% in 100°C. polychloroprenes. Of this 1,4 polymer only a small fraction has the cis configuration. This proportion increases from less than 5% in -40°C. polymer to ca. 13% in 100°C. polymer. Small amounts of branched structures that result from 1,2 and 3,4 polymerization are observed. These also increase in concentration with higher polymerization temperatures but do not account for more than 2.5% each even in 100°C. polychloroprenes. The portion of these polymers unaccounted for by these observations amounts at the most to 10% in 100°C. polymers. It is suggested that this part of the structure is that formed by hydrolysis and/or rearrangement of a part of the tertiary allylic chloride units which result from 1,2 polymerization of chloroprene. It is shown that only 50% of an acid-catalyzed ionic polychloroprene can be accounted for by structures recognized in free-radical polychloroprenes.

Notes: Anomalous flow is considered to be associated with a transition of the particles, representing the units of flow from a state of greater order to a state of greater disorder or vice versa. The particles in the ordered state are, in general, understood to belong to regions where they are in positions of minimum potential energy. A change in the internal structure is accompanied by a variation in the number of vacancies or holes present. Expressing anomalous viscosity as a function of the fraction of the particles in the disordered state and of the fraction of holes present, it is shown that the rate of change in the concentration of these particles is the same as the rate of change in the concentration of the holes. The equilibrium constant is: \documentclass{article}\pagestyle{empty}\begin{document}$$ K = {{\eta '} \mathord{\left/ {\vphantom {{\eta '} {\eta '_0 }}} \right. \kern-\nulldelimiterspace} {\eta '_0 }} = \exp \left\{ {{{\Delta F} \mathord{\left/ {\vphantom {{\Delta F} {kT}}} \right. \kern-\nulldelimiterspace} {kT}}} \right\} $$\end{document} where η0′ refers to a viscosity at a state near that of rest. ΔF is the change in the free energy of activation for a particle going from one state to another. This energy change is related to the change in kinetic energy, ΔEk, which permits the calculation of the mass of a particle. Experimental data are given for an asphalt whose shear rate is a power function of the shearing stress and for an asphalt whose shear rate is an exponential function of the shearing stress. It is shown that, in the first case, the degree of disorder increases with increasing stress, and that, in the second case, flow results in an orientation of the particles. In both cases the mass of a particle is considerably larger than that of a molecule. It would appear therefore that shear does not consist here in a shift of a particle from one position to another but is rather similar to slip in metals.

Notes: Assuming complete dissociation of the mineral acid in dilute aqueous solutions of a 1:1 vinyltoluene-styrene copolymer sulfonic acid and HCl, the degree of dissociation of the polyacid is apparently a constant independent of the concentration of either solute. On the basis of this result, it is likely that the polysulfonate chain initially contracts in such a manner with increasing HCl content of the solution that a maximum number of sulfonate groups remains on the surface of the coil. The variation of reduced viscosity (ηsp/c) with polyelectrolyte concentration c in the presence of a finite quantity of added “normal” electrolyte is determined mainly by the ratio of the counterions resulting from polyelectrolyte dissociation to the total counterion content of the solution. In regions of high dilution, where counterions from the polyelectrolyte are much less numerous than those from HCl, an apparently linear increase of reduced viscosity with increasing polymer concentration is observed. These data probably can be extrapolated to infinite dilution. Over the range of HCl concentrations 10-4 to 10-2 equivalent per liter the reciprocal square root of such extrapolated polysulfonic acid “limiting viscosity numbers” is proportional to the pH of the solvent. At the maxima of reduced viscosity plots the contribution of the polyelectrolyte to the hydrogen ion activity of the solution is half the contribution of the HCl: i.e., one third of the hydrogen ion activity is the result of polyelectrolyte dissociation. Moreover, the reduced viscosity at the maximum is directly proportional to the pH of the solvent. Curves of ηsp/c vs. c at high dilutions and constant pH are parabolas rather than straight lines. It is permissible to postulate rather convincingly from our data that the reduced viscosity curve of the polysulfonic acid in water possesses a maximum accurately indicated by the intercept of a Fuoss plot (cf. equation (7) in the text). The intercept of a Fuoss plot for any polyelectrolyte can have the significance of a limiting viscosity number only when measurements are made in a nonionizing solvent.

Notes: Second-order transition temperature of copolymers of butadiene and the following monomers, acrylonitrile, styrene, dimethylbutadiene, and methyl acrylate has been determined using the dilatometer method. That of polyacrylonitrile has been estimated by extrapolation of data. Mercury or 38% sulfuric acid was used as confining fluids. It has been found that the logarithm of the second-order temperature in degrees Kelvin is a linear function of the weight fraction of monomer.

Notes: Human blood is known to coagulate much more slowly in glass vessels lined with a very thin film of methyl silicone than in similar vessels with clean glass walls. In an attempt to explain this observation, the effect of various surfaces on the simpler system of egg albumin in aqueous buffer was studied. It was found that little or no denaturation of the albumin occurred when the solution of it was shaken for extended periods in either clean glass or silicone-lined bottles in the absence of air. In the presence of a gas interface denaturation was fairly rapid, but proceeded at a somewhat lower rate in silicone-treated bottles (coated by exposure to the vapor of mixed methylchlorosilanes) than in clean bottles. A relatively thick oily film of methyl silicone deposited by another method greatly increased the rate of denaturation, an effect due to a large degree to the increased oil-water interface created by the dispersion of silicone oil droplets in the solution during shaking. Kinetic studies show that the over-all denaturation is first-order, regardless of the type of surface. A theoretical interpretation of these observations in terms of possible mechanisms is given.

Notes: Polyisoprenes and polybutadienes have been prepared by bulk polymerization at hydrostatic pressures of from 5,000 to 10,000 kg./cm.2. The microstructures of these polymers have been determined by infrared analysis. In general, the structures are not grossly different from bulk and emulsion polymers prepared at near atmospheric pressure.

Notes: Data for a number of vinyl polymer-solvent systems show that the constant Ks in the relation 1/S = (1/S0) (1 + KsC) (where S and S0 are sedimentation constants at the concentration C and zero respectively) is proportional to the intrinsic viscosity. The average constant of proportionality is 1.6. Assuming the Mandelkern-Flory theory of the relation of frictional coefficient and intrinsic viscosity to root-mean-square end-to-end distance and Burgers' relation for the sedimentation constant of a dilute suspension of spheres, the ratio Ks/[η] is calculated to be 1.66. Molecular weights may be calculated from Ks and the limiting sedimentation constant, S0 without the use of the constants Φ and P, and agree well with molecular weights determined independently. These considerations apparently do not apply to cellulose derivatives, for which Ks is not proportional to [η].

Notes: As a consequence of earlier establishment of electrostatic repulsion between nonterminal polar 1,2-disubstituted olefins in polymers and like adding monomer, polar methylenic monomers were examined for such an effect. Acrylonitrile was found to exhibit such behavior in at least three systems: styrene-acrylonitrile, α-methylstyrene-acrylonitrile, and α-acetoxystyrene-acrylonitrile. Absence of such an effect was shown for methacrylonitrile, methyl acrylate, acrylic acid, methacrylic acid, and crotonic acid. A modified copolymerization equation involving r1, r1′, and r2 was presented. A convenient means of estimating r1 and r2 in this equation as well as in the ordinary copolymerization equation was shown.