Dynamics and Phase Equilibra of Polymers: Finite Size Effects

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Green 9705101 The overall goal of this study is the development of a microscopic understanding of the effects of confinement and of surfaces and interfaces on the dynamics and phase stability of polymeric thin film mixtures. The strategy is to use information about the interface as a probe to understand the phase stability and dynamics. A critical aspect of this strategy is focused at independently "tuning" the molecular parameters of the substrate and of the polymers in mrder to have control over the molecular interactions. This will involve novel synthesis of new norborene-like polymers with varying functionalities, synthesis of novel inorganic tellurium dioxide-based glasses whose reactivity can be tailored and surface treatments of a silicon substrate. The proposed study is divided into two parts, the first of which involves using a combination of variable angle spectroscopic ellipsometry (VASE) and forward recoil spectrometry (FRES) to study the development of the interfacial thickness between homopolymer bilayers of varying thickness, L. Information learned from the equilibrium interfacial thickness from this aspect of the study will give insight into the effect of copolymers (random and diblock) on the phase stability of the mixtures. The second phase of this proposal involves a related study of the formation of wetting layers and coexistence phases in mixtures of these polymers in contact with the substrates of varying characteristics in order to gain insight into the role of the "interfacial" fields on the formation and growth of the wetting layer in homopolymer mixtures. An additional aspect of this work is to use information about the wetting layer to develop new insights into the effect of copolymers on the phase stability of the thin film mixtures. %%% Interest in this area is motivated by technological need since thin film polymers serve "active" and "passive" roles in many technologies. For example, they serve "active" roles in microsen sors, large area light emitting displays and selective membrane applications. "Passive" applications include use as protective coatings and lubricants for magnetic storage media, biocompatibility and use as thin film adhesives. Because information about bulk properties provides limited guidance, it is critical to develop a fundamental understanding of polymeric properties under these conditions. ***