The influence of molecular architecture on grain structure and on material properties, particularly mechanical and transport properties, was investigated. A phenomenon, which we call Excluded Volume Epitaxy, causes intergrain orientational correlations during growth of anisotropic grains, and is the result of the space filling characteristics of anisotropic grains. In AnBn miktoarm star block copolymers, stars with n = 2, 4, and 16 show greater long range order and faster grain growth kinetics than the corresponding diblock (n = 1). In contrast to single junction point stars, long range order was found to be suppressed in graft copolymers with increasing number of branched points. We have studied both mechanical and transport (gas permeability and proton conduction) properties as a function of controlled grain size and orientation. In general, for randomly oriented grains, a smaller grain structure, for the same composition, was found to result in higher mechanical strength and higher permeability.

Grain structure development and influence on block copolymer transport and mechanical properties

243rd National Meeting (2012)

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