Light Scattering from a Two-Phase Polymer System. Scattering from a Spherical Domain Structure and Its Explanation in Terms of Heterogeneity Parameters

Abstract

tion of the equilibrium stress-optical coefficients in connection with the light-scattering results shows that the reorganized regions should exhibit a higher form anisotropy the larger the value of A/app. Such increasing form anisotropy can be either due to increasing anisometry of the regions or-at a given anisometrydue to an increasing refractive index difference with the surrounding.The reasons for the appearance of some fairly longrange anisotropic structures in the PHEMA hydrogels have previously, in the first place, been traced to the amphiphilic nature of the polymer chain, which especially in water could lead to regions of micromesomorphic order.1 234 56Inhomogeneous cross-linking may be a second contributing factor, especially if water is present during network formation.The optical behavior can be qualitatively understood Scattering from a Spherical Domain Structure 433 in terms of a somewhat organized network containing cross-links and entanglements. Any cross-link or entanglement will restrict the long-range organization.The movement of entanglements during stress relaxation will change the interchain correlations, so that a restructuring will result. At small A/app the equilibrium optical behavior will approach the Gaussian behavior because the large number of cross-links disrupts the organizing tendency of the amphiphilic system.Acknowledgments. The financial support of the Syracuse University Research Institute is gratefully acknowleged. M. I. expresses his gratitude to the Institute of Macromolecular Chemistry, Czechoslovak Academy of Sciences, for granting a leave of absence, which made his postdoctoral stay in the U. S. possible. J. Hasa, Prague, has kindly cooperated in the preparation of the samples.

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