Crystallization‐dominated and microphase separation/crystallization‐coexisted structure of all‐conjugated phenylene–thiophene diblock copolymers. Issue 24 (16th September 2015) - Yu, Xinhong
ABSTRACT: The crystallization‐dominated and microphase separation/crystallization‐coexisted structure of the all‐conjugated diblock copolymers poly(2, 5‐dihexyloxy‐ p ‐phenylene)‐ block ‐(3‐hexylthiophene) (PPP‐ b ‐P3HT, denoted as BmTn) with different block compositions was affected by the aggregation state of the diblock copolymers in solvents with different solubilities. For B34T66, B62T38, and B75T25, the coexistence of microphase separation and crystallization was obtained in good solvent with few crystalline aggregates. For B34T66 with a longer P3HT block, densely stacked fiber crystal structures in thin films were found by using marginal solvents with crystalline aggregations in solutions. As for B62T38 and B75T25 with shorter P3HT block and longer PPP block, crystal structures were obtained by the use of solvents with a much larger solubility difference of the two blocks. Thus, microphase‐separated structures are prone to form from solutions with coil conformation and fiber crystals from solutions with larger aggregates, which resulted in the increased crystallinity. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys.2015, 53, 1718–1726 Abstract : The solvent effect on the crystallization and microphase separation of crystalline–crystalline conjugated diblock copolymers with different main chain compositions was investigated. The choice of solvents with different solubilities allowed for the tuning of the aggregation state of the diblock copolymers in solution. The difference of crystalline aggregates in solution further modulates the competition between crystallization and microphase separation of the two conjugated blocks in the thin film forming process, resulting in different film morphologies.