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  • 11
    Electronic Resource
    Electronic Resource
    Polymerizable amphiphiles, 2. Micellization of 1-O-3-(4-vinylphenyl)propyl-β-D-glucopyranosePart 1: Cf.10. (1987)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 188 (1987), S. 537-560 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 1-O-3-(4-Vinylphenyl)propyl-β-D-glucopyranose (1) undergoes in water a closed association under formation of N-mers. The unimer/N-mer association is directly visible in the Schlieren pattern of ultracentrifugal synthetic boundary experiments. Association numbers and mass-concentration-based equilibrium constants of association were calculated from the variation of N-mer concentrations with unimer concentrations and from the concentration dependence of inverse apparent average molar masses as measured by both vapor phase osmometry and sedimentation equilibrium. Association numbers were also calculated from the combination of sedimentation coefficients with diffusion coefficients, sedimentation coefficients with intrinsic viscosities, and diffusion coefficients with interinsic viscosities as well as from the dependence of apparent mass-average molar masses on inverse apparent number-average molar masses. All methods gave in general different association numbers and equilibrium constants. The effect, which was not found for other non-ionic amphiphiles, is probably due to the existence of consecutive equilibria between the unimer and a low molar mass P-mer which associates to a higher molar mass R-mer. Viscosity data are in agreement with the picture of a spherical micelle for the dominant P-mers with about 10 water molecules per glucose residue. The micellization of 1 is both enthalpy- and entropy-driven, in contrast to the micellization of 1-O-octyl-β-D-glucopyranose which is a strictly entropy-driven process.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1987.021880308
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  • 12
    Electronic Resource
    Electronic Resource
    Multimerization: Association and aggregation. XIII. Concentration dependence of apparent average molecular weights of a poly-disperse associating polymer in a theta solventFor the previous part of this series see Elias and Vogt.1 (1973)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 11 (1973), S. 137-148 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Analytical expressions are derived for the concentration dependences of different apparent average (n,w,z) molecular weights for two types (end-to-end and segment-to-segment) of open association of polymolecular unimers. The open association is defined as an association leading to an unlimited number of multimer species. The type of association depends upon the number of associogenic sites per unimer molecule: for the end-to-end type this number is constant, whereas for the segment-to-segment type it is proportional to the degree of polymerization of the unimer. For the end-to-end association, a simple relation exists between the polydispersity (M̄r)w/(M̄r)n of the mul-timer and the association number r and the polymolecularity (M̄I)w/(M̄I)n of the unimers: (M̄r)w/(M̄r)n = 1 + r-1[(M̄I)w/(M̄I)n - 1]. The z-average and higher averages of the r-mers may be lower than the corresponding averages of the unimers. In the theta-state, (M̄n)app,Θ and (M̄w)app,Θ are linear functions of c/(M̄n)app,Θ, whereas a more complicated relation exists for the apparent higher averages. For the segment-to-segment association, both (M̄w)app,Θ and (M̄z)app,Θ are linear function of the weight concentration c, whereas no closed expression could be found for (M̄n)app,Θ. For the polydispersities of multimers one finds (M̄I)z/(M̄r)w = 1 + r-1[(M̄I)z/(M̄I)w - 1], and, in the special case of a Schulz-Zimm distribution of unimer molecular weights, (M̄r)n/(M̄r)w = 1 + r-1[(M̄I)n/(M̄I)w - 1].
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1973.180110113
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  • 13
    Electronic Resource
    Electronic Resource
    Multiphase equilibria in solutions of polydisperse homopolymers. I. Three-phase equilibria in ternary and quasiternary systems (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 20 (1982), S. 1947-1961 
    Details
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: A recent critique of the mechanism of three-phase separation suggested by Tompa for ternary system solvent-polymer (1)-polymer (2) is shown to be invalid, and Tompa's account is reinforced by analytical arguments and numerical results. In particular it is proven that the critical point in some simple Flory-Huggins systems is thermodynamically unstable, rather than just metastable. Three-phase separations in quasiternary systems cannot be studied by simple methods advanced for treatment of true ternary systems. Rather a new, more general, approach is required for these cases.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.180201017
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  • 14
    Electronic Resource
    Electronic Resource
    Analysis of polymer membrane formation through spinodal decomposition. III: Two-dimensional simulations of early-stage behavior (1993)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 33 (1993), S. 1033-1041 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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
    Notes: A nonlinear diffusion equation is used to study early-stage spinodal decomposition of polymer solutions, in relation to the membrane formation, in two dimensions. The effects of overall polymer composition and composition-dependent mobility and diffusivity are included in our simulations. Our results show a kinetically stable structure is established during the early stages, which corresponds to a circular range of peaks in the two-dimensional frequency spectrum. Such a spectrum is found to result in an interconnected cell structure in the two-dimensional real space. A decrease in the level of polymer interdomain interconnectedness is obtained as time increases, which indicates the influence of interfacial tension. As the overall polymer composition is increased, an increase in interdomain distances is observed, although the same early stage morphological structure is obtained. Finally, calculated interdomain distances from the two-dimensional simulation are larger than those obtained in equivalent one-dimensional model systems.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760331605
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  • 15
    Electronic Resource
    Electronic Resource
    Morphological studies of late-stage spinodal decomposition in polystyrene-cyclohexanol system (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 55 (1995), S. 753-759 
    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
    Notes: We studied the late-stage spinodal decomposition of the polystyrene-cyclohexanol system in relation to membrane formation. Phase separation was effected by the removal of thermal energy from the homogeneous polymer solution. The ultimate morphology of the phase-separated systems has been studied using electron microscopy and has been found to be strongly affected by the quenching time. A shift from a highly interconnected open-cell structure to a closed-cell structure has been observed, indicating the transition of the spinodal decomposition from early to late stages. The cell growth in the late stage has been quantitatively analyzed and a power-law relationship between the cell size and quenching time has been found. The resulting exponent of 0.61 is consistent with literature values from light-scattering measurements, as well as from theoretical derivations. © 1995 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1995.070550512
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  • 16
    Electronic Resource
    Electronic Resource
    Monte Carlo studies of isolated AB block copolymer molecules (1977)
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 17 (1977), S. 622-626 
    Details
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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
    Notes: Recent theoretical progress in understanding conformations of AB block copolymer molecules in dilute solution is reviewed. The results of the authors' own biellipsoidal smooth density model (BEM) are compared to the findings recently reported by two independent groups, for the more rigorous self-avoiding walk models with nearest neighbor interactions (SAW). The SAW results confirm the BEM conclusions for the size and shape behavior of individual blocks under changing solvent-temperature conditions. The relative orientation and separation of the blocks depend strongly, on the magnitude of AB interactions, while the individual, block parameters are much less sensitive in this respect. Parfial segregation (or partial block mixing) is the general rule rather than the exception, and is aided by the low polymer concentrations which are, found in the overlap region in dilute solutions. A unified view of homopolymers and block copolymers emerges from these models, with homopolymers being a special case of the latter group. Inherent to BEM is the arrowhead-like overall shape of the molecules, which appears to survive under most conditions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pen.760170820
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  • 17
    Electronic Resource
    Electronic Resource
    Multimerization: Association and aggregation, 14Part 13: cf.1.. Distinction between open and closed associations (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 176 (1975), S. 365-371 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Offene und geschlossene molekül-abhängige Assoziationen mit experimentell nur unvollständig bekannten Konzentrationsabhängigkeiten der scheinbaren Molekulargewichte können durch eine Auftragung der scheinbaren Gewichtsmittel (Mw)app des Molekulargewichtes gegen die reziproken scheinbaren Zahlenmittel (Mn)app-1 des Molekulargewichtes unterschieden werden. Für geschlossene Assoziationen sind für Theta-Systeme Geraden und für nicht-Theta-Systeme von Stäbchen konkave Kurven zu erwarten. Offene Assoziationen führen sowohl für Theta- als auch für nicht-Theta-Systeme in diesen Fällen zu konvexen Kurven. Beide Assoziationssysteme geben bei hohen Konzentrationen in nicht-Theta-Systemen Schleifen. Ähnliche Diagramme können mit scheinbaren z- und Gewichtsmitteln des Molekulargewichtes konstruiert werden.
    Notes: Open and closed molecule-based associations with experimentally incompletely accessible concentration dependencies of the apparent molecular weights can be distinguished by plotting the apparent weight average molecular weight, (Mw)app, versus the inverse apparent number average molecular weight, (Mn)app-1. For closed associations, straight lines are observed for theta-systems and concave ones for non-theta-systems of associating rods. Open associations in these cases give convex lines for both, theta and non-theta-systems. Loops can be expected for both types of associations for non-theta-systems at high concentrations. A similar plot can be based on apparent z and weight average molecular weights.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.021760210
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