Influence of Solvent Polarity on the Self-Assembly of the Crystalline–Coil Diblock Copolymer Polyferrocenylsilane-b-polyisoprene

Many poly(ferrocenyldimethylsilane) (PFS) block copolymers form fiber-like micelles with a semicrystalline core in selective solvents. Solvent effects on micelle formation are not well understood. This paper compares micelle formation for a sample of PFS50–PI1000 (the subscripts refer to the number-average degrees of polymerization) in decane with that in tert-butyl acetate (tBA), a more polar solvent. When micelle formation is seeded, by adding block copolymer as a concentrated solution in tetrahydrofuran to solutions of micelle fragments, micelle growth was similar in both solvents. Micelles with a narrow length distribution were formed and the length increased in proportion to the amount of polymer added. In contrast, when micelles were prepared by heating a sample of the block copolymer in decane or tBA to 90 °C and allowing the solution to cool, pronounced differences were observed. In decane, micelles with a uniform width (10 nm) and a length on the order of 5 μm formed after 1 h, and grew to about ...