ALBERT

Notes: Abstract Within the Jet Propulsion Laboratory in Pasadena, California, state of the art computer graphics animation is done in the Computer Graphics Laboratory. The topics of the animations cover many scientific disciplines. Specific features of the system developed there, both hardware and software, are discussed. The prime mover of the effort is Dr. James F. Blinn of Pasadena; his role and experiences are elaborated. Their current largest project is The Mechanical Universe; the system is used for its production.

Notes: Oligomers of 4-vinylpyridine were prepared by reaction in vacuo of 4-vinylpyridine with lithio-4-ethylpyridine at -78°C, followed by reaction with CH3I(13CH3I) or CH3OH. The stereochemistry was studied by NMR and GC. Methylation and the addition of 4-vinylpyridine occurred in a stereochemically nonselective manner. The data also indicated that in contrast to the oligomerization of 2-vinylpyridine the stereoisomeric meso and racemic 4-pyridyl carbanions propagated with equal reaction rates. The stereochemistry was readily explained by an absence of coordination of the Li ion by the nitrogen of the penultimate pyridine ring observed in the corresponding oligomerization of 2-vinylpyridine.

Notes: A comparative ESR study of low-temperature photolysis at 77 and 4.2 K of isotactic polypropylene, preoxidized under controlled conditions, and of 2.6.8 trimethylnonane-4-one as a model compound of the inchain PP ketones —CH2COCH2— is presented. The results show conclusively that the ESR spectra of low-temperature PP photolysis reported in the literature arise from the decomposition of tertiary hydroperoxides, whereas the contribution by the Norrish I photolytic cleavage of ketones is of minor importance; the relative efficiency of radical production at 77 K (λ ≥ 300 nm) by both types of photoactive compound has been measured by ESR and found to be about 15 times greater for the hydroperoxides. The mechanism of solid-state photolysis of PP hydroperoxides is dominated by the nearly complete decay of excited alkoxyls during the photolytic events that yield the chain end radicals —CH(CH3)CH2· by β scission (87.8%) and the inchain radicals —CH2C(CH3)CH2— by hydrogen abstraction (10.4%). The low yield of methyl radicals detected (1.8%) and their delayed appearance strongly suggest that these species are of secondary origin and that the decomposition of alkoxyls via C—CH3 scission is of negligible importance. From the ESR anisotropy of the deliberately prepared peroxyradicals —CH(CH3)CH2O2· and —CH2C(CH3)(O2)CH2— evidence of the misalignment of terminal chain segments following scission of alkoxyls at 77 K was obtained. An unexpected result of the measurements at 4.2 K is represented by the identification of a clear signal by H atoms: the H atoms apparently are not trapped in perprotiated matrices, even at 4.2 K, because of their unusually high reactivity toward the hydrogen abstraction assisted by tunneling effects.

Notes: Poly[S-(2-9′-acridinylethyl)-L-cysteine] (5) was synthesized by the N-carboxy anhydride procedure. It was converted to the trifluoroacetic acid salt (6), which was treated with LiTCNQ in methanol to give the TCNQ anion radical salt (7). 7 showed electrical conductivity of 10-8 S/cm at 295 K.

Notes: More than a hundred propylene polymerizations were carried out with the CW catalyst (our particular MgCl2/ethylbenzoate/p-cresol/AlEt3/TiCl4 supported high mileage catalyst). Highest I.I. index (% yield of boiling heptane insoluble product) of 96.2 ± 0.9 was obtained at [Ti] = 2.4 × 10-4 M, A/T (amount of AlEt3 with 0.33 equivalent of methyl-p-toluate to amount of Ti in the catalyst) = 167 at 50°C. The I.I. values became lower when any one of these variables was changed. The I.I. values did not change with time of polymerization, indicating that both stereospecific and nonstereospecific sites were produced at the same time and polymerized monomers during the course of a polymerization. Estimates of maximum active site concentrations, [Ti*]0,Because of the complexity of the catalyst system, the active sites are designated as follows: [Ti*], active sites of all kinds at a given time; [Ti*]0 active sites of all kinds at time zero; [Ti1*], active sites of the first kind formed initially upon activation; [Ti2], active sites of the second kind, which were transformed from the former, and are responsible for olefin polymerization after the initial phase of rapid decay of activity; [Ti*]i, stereospecific active sites; [Ti*]a, nonstereospecific active sites, and [Ti*]t = [Ti*]i + [Ti*]a Similarly, the subscripts 1 and 2 for the various rate constants refer to active sites Ti1* and Ti2*, respectively. Finally [Ti] is the concentration of total titanium in the amount of catalyst used. [Ti-P] is the titanium polymer bond concentration as determined by 14CO tagging; [Ti-P] (1 h) and [Ti-P] (48 h) are the values obtained with indicated time of contact of 14CO with the polymerization mixture in the obsence of monomer. were obtained from a variation of vn-1 versus t-1. The values of [Ti*]0.i and [Ti*]0,a for the stereospecific and nonstereospecific sites, respectively, are in excellent agreement with those values of [MPB]0 (metal polymer bond concentrations at t = 0) determined earlier by radiotagging with tritiated methanol. The rate of formation of [Ti*]1 (the initial active site) is first order with respect to [Ti] and [A] with an activation energy of 12 kcal mol-1 where [A] is the AlEt3 concentration. The rate constants of propagation at 50°C are kp,i ∼ 160M-1s-1 and kp,a ∼ 11M-1s-1. The activation energy for the stereospecific propagation is about 4.1 kcal mol-1. At 50°C the rate of polymerization decreases according to second order kinetics suggesting bimolecular processes which transform one-half to one-fourth of the Ti1* site to Ti2* types depending upon experimental conditions, while the remainder decay to inactive species. The values of kt1 lie between 19 and 61M-1s-1. These processes are more complicated at 70°C involving two consecutive reactions; at low [A], the data fits better with first order decay kinetics. Comparison of the [Ti2*] values and the values of [Ti-P] obtained by 14CO tagging suggests that CO reacts primarily with the Ti2* sites and very little with the initially formed Ti1* sites. The Ti2* sites are slightly less active than the Ti1* sites having kp2,i ∼ 86M-1s-1 and kp2,a ∼ 7M-1s-1 at 50°C.

Notes: The polymerization of methyl methacrylate within solid matrices of stereoregular poly(methyl methacrylate) has been studied by proton NMR and wide angle X-ray diffraction. The semi-crystalline isotactic (i-) PMMA matrix was synthesized in the laboratory by anionic polymerization initiated by phenylmagnesium bromide, and the syndiotactic (s-) PMMA matrix was synthesized through a Ziegler-Natta reaction. Matrix polymerization of the monomer was initiated through the redox activation of benzoyl peroxide with N,N-dimethyl-p-toluidine. NMR measurements of triad distributions in matrix-polymerized chains suggest that the well-known stereospecific replica polymerization in PMMA (syndiotactic sequences promote isotactic sequences and vice versa) plays only a limited role in the systems studied. Experimental results indicate that chains grown within the i-PMMA or s-PMMA solid matrices have greater degrees of configurational disorder. The greater concentration of atactic triads in these chains could be the result of limited free volume or steric effects during polymerization in a highly condensed environment. X-ray diffraction studies of solution cast blends of isotactic PMMA and PMMA with conventional tacticity reveal some crystallinity with a structure characteristic of the stereocomplex formed by isotactic and syndiotactic PMMA from suitable solvents. Evidence was obtained for the presence of this complex in solidified mixtures of the i-PMMA solid matrix and liquid monomer. This observation is an example of special intermolecular structures that can form under conditions of in situ growth of chains within a pre-polymerized matrix.

Notes: Metal powders were incorporated into various elastomers and the mixtures were subjected to intense shearing in air or a nitrogen atmosphere. The molecular weight after shearing was still relatively high, however; greater than 100 kg/mol. The elastomer was then dissolved and centrifuged to remove the metal particles and the solution was analyzed for reaction products. A strongly ultraviolet (UV)-absorbing species was formed by shearing a styrene-butadiene copolymer (SBR) with iron powder. The concentration increased with the concentration of iron powder in the mixture and the extent of shearing, and it was greater after shearing in a nitrogen atmosphere. These results are attributed to the direct reaction of macromolecular radicals, formed by shearing, with iron powder to yield an iron-polymer compound. Natural rubber (cis-polyisoprene), which absorbed 100-200 μg of iron per gram of polymer, was about as reactive as SBR. Polybutadiene was less reactive, and an ethylene-propylene copolymer did not react with or solubilize a significant amount of iron. Zinc was, in general, solubilized to a somewhat lesser degree than iron, whereas aluminum powder appeared to undergo virtually no reaction with sheared elastomers. The maximum extent of reaction (solubilization) was of the order of one metal atom per final polymer molecule, which was consistent with the proposed mechanism. Moreover, an analogous reaction took place between simple organic radicals and iron particles in suspension.

Notes: 1,4-Oxathian-2-one (1a) was prepared in high yield by oligomerization of methyl(2-hydroxyethyl)mercaptoacetate (3) followed by catalytic depolymerization in vacuo. A similar sequence starting with methyl(2-hydroxyethyl)sulfonylacetate (5) afforded the corresponding sulfone, 1,4-oxathian-2-one-4,4-dioxide (1c), however, 1,4-oxathian-2-one-4-oxide (1b) could not be obtained by this procedure. Ring opening melt polymerization of 1a and 1c afforded low molecular weight crystalline polyesters 2a and 2c. Oxidation of 2a with m-chloroperoxybenzoic acid produced the corresponding polyester 2b containing sulfoxide groups. Thermogravimetric analyses and visual observations indicated 2b to be thermally unstable relative to 2a and 2c.

Notes: Dissolving pulp and its partially xanthated derivative were grafted with styrene, using either the Fe2+-K2S2O8 redox system of potassium persulfate alone as initiators. The conversion of styrene to both copolymer and homopolymer was found to be influenced by agitator speed. The effect of stirring was much more pronounced with the xanthated substrate in that a welldefined conversion maximum was observed at the same agitation speed for both total polymer and copolymer. Grafting onto dissolving pulp with the redox initiator also showed a maximum, but a maximum total polymer and maximum copolymer were located at different agitator speeds. Grafting of styrene onto dissolving pulp initiated by potassium persulfate was almost independent of stirring in the 0-910 rpm range.

Notes: Vinylsulfonylethyl (VSE) derivatives of the nucleic acid bases adenine, thymine, cytosine, and the nucleosides inosine and uridine have been prepared via a simple Michael reaction with divinyl sulfone. The VSE derivatives were grafted on a polyethyleneimine (PEI) backbone. PEI of different molecular weights (1400, 1800 and 50,000-100,000) were used and also two different molar ratios (1:1 and 1:2) of monomer to PEI were employed. From the 1H-NMR and elemental analysis, it appeared that in almost all instances the grafting was quantitative. In one case, both 1-VSE-thymine and 9-VSE-adenine were grafted on the same PEI backbone. Interactions between some of these polymers were investigated by UV spectroscopy. The expected complementary base pairing was observed only in DMSO-ethylene glycol solvent system but not in DMSO. The adenine polymer showed a one-to-one interaction with the thymine polymer.