Influence of Block Sequence on Solution Self-Assembly of Triblock Terpolymers Containing Crystalline π-Conjugated Polythiophene

The fabrication of nanostructures is an urgent yet challenging process due to the complicated parameters involved in the self-assembly process. Uniquely, acting as the most efficient strategy, the self-assembly behavior of multiblock copolymers can be significantly modulated by varying the block sequence parameter. In this study, polyisoprene (PI), polystyrene (PS), and crystalline π-conjugated poly(3-hexylthiophene) (P3HT) were elaborately combined into PI- b -PS- b -P3HT, PS- b -PI- b -P3HT, and PS- b -P3HT- b -PI triblock terpolymers with different block sequences via controlled synthetic methods. The self-assembly of triblock terpolymers was comprehensively investigated and compared using n -heptane/ethyl acetate (Hep/EA) and N, N -dimethylacetamide/ethyl acetate (DMAc/EA) as selective cosolvents. Under the same cosolvents and degree of polymerization (DP) of the blocks, the block sequences were found to significantly influence the morphological formation of nano-objects due to variations in the crystallization ability of the P3HT block and selective solvation or plasticization of the PI or PS blocks. Furthermore, to provide a comprehensive understanding of the self-assembly and depict a full morphology diagram, the self-assembly behavior of triblock terpolymers with different block sequences was compared by varying the block compositions of the triblock terpolymers. This work provides fundamental insights into the self-assembly mechanism of rod–coil multiblock copolymers and has implications for designing functional nanomaterials.