As our polymerization toolbox expands, we can access increasingly more complicated block polymer architectures with high fidelity and low dispersity. This motivates efforts to predict how these block polymers will self-assemble. Even for linear block polymers, the number of published studies decreases as the number of blocks increases; for tetrablock polymers we are still in the earlier stages of exploratory research. We have synthesized linear ABCA’ tetrablock terpolymers (A = polystyrene; B = polyisoprene; C = polylactide) via sequential anionic, ring-opening, and RAFT polymerizations to achieve a range of molar masses and compositions. We examined the bulk phase morphologies of these materials using microscopy (primarily TEM) and SAXS. These structural and computational studies showed non-lamellar morphologies, even for systems with roughly equal volume fractions of each block. TEM and SAXS data produced unexpected disorder for tetrablock polymers whose triblock precursors formed ordered structures, and this behavior was corroborated by computation. Predicting and accessing equilibrium structures for tetrablock polymers remain challenges in utilization of these materials for their morphological properties. By coupling experimental and computational methods, we aim to improve prediction capabilities that should allow us to go beyond our single tetrablock system.

Experimental and computational exploration of ABCA’ tetrablock terpolymer morphologies

255th National Meeting (2018)

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