Rational Design of Versatile Self-Assembly Morphology of Rod–Coil Block Copolymer

Abstract

Controlling the nonlamellar and bicontinuous nanostructures through changing volume fraction is a well-developed technique for coil–coil block copolymer, but it is not always effective for rod–coil block copolymer due to strong rod–rod interaction. Versatile self-assembly morphology of rod–coil copolymer can be achieved by simultaneously adjusting the rod–rod interaction, rod–coil interaction, and conformational asymmetry. This approach has been investigated by using poly(3-alkylthiophene)-b-poly(methyl methacrylate) as a model. By altering the alkyl side chain of polythiophene from linear hexyl to longer dodecyl and to branch 2-ethylhexyl, both rod–coil and rod–rod interaction are decreased with increasing spatial occupation of alkyl side chain which have been quantitatively determined for this type of rod–coil copolymer. With tunable conformational asymmetry, competition between rod–rod and rod–coil interactions, and crystallization-driven force, the presence of versatile morphology, i.e., lamellar and ...