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  • 1
    Electronic Resource
    Electronic Resource
    Rigid rod polymers with flexible side chains. X. Thermotropic mesophases from aromatic stiff-chain polyamides bearing n-alkoxy side chains (1993)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 31 (1993), S. 1609-1619 
    Details
    ISSN: 0887-624X
    Keywords: liquid crystalline polymers ; polyamides ; smectic mesophases ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The synthesis of stiff-chain poly(1,4-phenylene terephthalamide)s substituted by two as well as by four flexible side chains per repeating unit is described. The solubility of the materials bearing only two side chains is still very low. Appending of four side chains leads to polyamides which dissolve in common organic solvents. All polyamides reported herein form layered structures in the solid state as well as in the mesophase. Polyamides with two side chains have a very weak tendency for crystallization and do not exhibit a transition to the isotropic state even for the longest side chains. Polyamides with four side chains show three reversible thermal transitions: a disordering transition of the side chains, a transition to a layered, smectic-like mesophase, and finally the transition to an isotropic melt. It is shown that the phase behavior of these materials is mainly governed by the strong segregation of main- and side-chains which can be compared best to the microphase separation in block copolymers. © 1993 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1993.080310631
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  • 2
    Electronic Resource
    Electronic Resource
    Properties of polymers. By D. W. van Krevelen, Elsevier, Amsterdam 1990, xxii, 875 pp., hardcover, $ 337.25, ISBN 0-444-881 60-3 (1991)
    Weinheim : Wiley-Blackwell
    Advanced Materials 3 (1991), S. 517-518 
    Details
    ISSN: 0935-9648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/adma.19910031019
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  • 3
    Electronic Resource
    Electronic Resource
    Kinetics of orientation of a side-chain liquid-crystal polymer as measured by a high-temperature SQUID-magnetometer (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 1199-1206 
    Details
    ISSN: 0887-6266
    Keywords: liquid crystalline polymer ; magnetometer study of kinetics of orientation of ; orientation kinetics of nematic phase measured by SQUID-magnetometer ; magnetic susceptibility measurements of orientation kinetics of liquid crystals ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A superconducting quantum interference device (SQUID) magnetometer suitable for measurements of the magnetic susceptibility up to 600 K has been used to follow the kinetics of realignment in the nematic phase of a side-chain liquid-crystal polymer. Experiments are performed using monodomain and polydomain samples. Results obtained in monodomain samples are in quantitative agreement with the prediction of the continuum theory up to an angle of approximately 60°. Experiments conducted at higher starting angles give clear indication of backflow effects. Data obtained from experiments on polydomain samples have been compared with model calculations using the data on the monodomain samples. This comparison leads to the conclusion that in this case backflow effects play an important role, too. All results show that SQUID magnetometry allows monitoring of the kinetics of realignment with highest precision. © 1992 John Wiley & Sons, Inc.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1992.090301104
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  • 4
    Electronic Resource
    Electronic Resource
    Compatibility of coils and rods bearing flexible side chains (1987)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 25 (1987), S. 739-747 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: We present a theoretical treatment of nematic-isotropic phase equilibria in mixtures which consist of random coils and comblike polymers, the latter components being composed of a rigid backbone and flexible side chains. The mixing partition function is evaluated by using the Flory lattice model. The comblike component is characterized by the axial ratio xr of its rigid main chain and the number of flexible side chains z, each containing m segments. The coiled component is described by its number of segments xc. The net exchange energy of mixing is assumed to be zero; i.e., we consider athermal solutions. It is shown that the flexible side chains attached to the rigid main chains markedly enhance the compatibility in the isotropic phase. If the ratio of the volume fraction of the side chains to the volume fraction of the main chains is high enough, there is even a finite range of concentration where the random coils mix homogeneously with the comblike component. This is in contrast to mixtures of rods and coils, which have been shown by Flory to be incompatible over nearly the full range of composition. These conclusions hold true only when ordered states are involved. For comblike polymers with flexible backbones mixed with random coils in isotropic melts, the resulting free energy of mixing is given by the familiar Flory-Huggins expression.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1987.090250404
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  • 5
    Electronic Resource
    Electronic Resource
    Synthesis and thermal analysis of copolyesters deriving from 1,4:3,6-dianhydrosorbitol, ethylene glycol, and terephthalic acid (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 1199-1202 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Study of particle interaction in a highly concentrated latex by turbidimetryRespectfully dedicated to Professor B. A. Wolf on the occasion of his 60th birthday (1996)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 47 (1996), S. 333-339 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study of the low-angle region of the static structure factor S(q) (q = (4π/λ) sin(θ/2); θ: scattering angle, λ: wavelength of the radiation in the medium) of a concentrated (44 wt.%) poly(methyl-methacrylate) (PMMA) latex by turbidimetry is presented. It is demonstrated that S(0), i.e., the structure factor extrapolated to vanishing scattering angle can be obtained in excellent accuracy up to the highest concentrations. Since S(0) reflects the balance between long-range attractive and short-range repulsive forces between the latex particles, this quantity can be used to assess the stability of the latex against flocculation. Special attention has been paid to the influence of polydispersity on S(0). The analysis of S(q) in the vicinity of q = 0 for the system under consideration indicates the absence of attractive forces between the particles.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1996.010470803
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  • 7
    Electronic Resource
    Electronic Resource
    Rheological studies of moderately concentrated polystyrene solutions. I. A new method for the extrapolation of the zero-shear viscosity (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1205-1216 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Measurements of the viscosity coefficient η of solutions of polystyrene (Mw = 6.0 × 105 and 1.77 × 106) in trans-decalin (TD, θ solvent) and toluene (TL, good solvent) as function of shear rate (11-104 s-1), concentration (4.24-11.21 wt %), and temperature (10-50°C) are reported. As a new theoretically grounded method for the determination of the zero-shear viscosity η0 it is proposed to plot η as a function of $\left({\eta \dot \gamma} \right)^3$. The intercepts of the straight lines obtained by this procedure give η0 in good agreement with directly measured values.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180210719
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  • 8
    Electronic Resource
    Electronic Resource
    Rheological studies of moderately concentrated polystyrene solutions in the vicinity of the θ temperature. II. Shear-rate dependence for different thermodynamic conditions (1983)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 21 (1983), S. 1217-1226 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The viscosity data of moderately concentrated polystyrene solutions in trans-decalin (TD) (θ solvent, θ temperature 21°C) and toluene (TL) (good solvent) reported in Part I are discussed in terms of Graessley's entanglement theory. Under good solvent conditions, Graessley's master curve provides an excellent fit up to high shear rates, whereas in the vicinity of the θ conditions the data have to be modified by a parameter ηfric introduced by Ito and Shishido. The characteristic time of mechanical response to flow of chains approximately given by the shift factor τ0 is found in good solvents to be on the order of the Rouse relaxation time. In poor solvents, close to demixing, τ0 tends to much higher values, indicating a reduced chain mobility. The influence of temperature on the viscosity decreases with increasing shear. The resulting apparent energy of activation of flow shows very small or even negative values at high shear rates. This behavior can be explained by the modified Graessley theory, however, in a quite natural way.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1983.180210720
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  • 9
    Electronic Resource
    Electronic Resource
    Conformation and shape of rigid-rod polyesters substituted with flexible side chains as revealed by small-angle neutron scattering (1993)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 44 (1993), S. 139-147 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A small-angle neutron study of liquid crystalline main chain polyesters with flexible side chains is presented. Investigations in solution have been performed using protonated material dissolved in deuterated tetrahydrofuran and deuterated nitrobenzene. To determine the conformation in bulk, mixtures of deuterated and protonated material have been investigated at ambient and at elevated temperature. For this purpose, a route for the synthesis of fully deuterated polyesters has been developed. It is shown that the form factor measured in solution is compatible with an extended, rod-like conformation. Investigations in bulk show that a plate-like conformation is adopted under these conditions. This observation is in full agreement with earlier findings from structural studies which indicate that in bulk the side chains of a given main chain are located in a plane; i.e., the polyester molecule assumes a plate-like shape. Thus the present investigation demonstrates that there is a pronounced change of conformation when going from solution to bulk. The reason for this change are the packing constraints exerted by the neighbouring molecules in the bulk.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1993.010440305
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  • 10
    Electronic Resource
    Electronic Resource
    Small-angle x-ray analysis of latex particles using contrast variation (1993)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 44 (1993), S. 178-183 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A study of a core-shell latex consisting of a polystyrene core and a polymethylmethacrylate (PMMA) shell by small-angle x-ray scattering is presented. Since the electron density, i.e., the contrast of both polymers, can be easily matched by addition of sucrose to the dispersing agent water, the internal structure of the particles can be studied by contrast variation. The scattering intensities obtained at different contrast are all compatible with a concentric core-shell model which exhibits a finite nonuniformity of the thickness of the shell. The present analysis furthermore reveals that the interfacial region between the polystyrene and the PMMA phase must be very small.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1993.010440402
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