Cylindrical Micelles with "patchy" Coronas from the Crystallization-Driven Self-Assembly of ABC Triblock Terpolymers with a Crystallizable Central Polyferrocenyldimethylsilane Segment

Solution self-assembly of a series of linear ABC triblock terpolymers with a central crystallizable poly(ferrocenyldimethylsilane) (PFS) core-forming "B" block and terminal polystyrene (PS) and poly(methyl methacrylate) (PMMA) "A" and "C" blocks has been investigated. Three PS-b-PFS-b-PMMA triblock terpolymers with different block ratios (1, 3.6:1.0:4.7; 2, 7.0:1.0:6.9; and 3, 1.1:1.0:1.4) but with similar degrees of polymerization for the central PFS block were prepared through a combination of living anionic and atom-transfer radical polymerization techniques, together with azide/alkyne "click" chemistry. Cylindrical micelles with a crystalline PFS core were formed in solvents selective for the terminal PS and PMMA blocks. In ethyl acetate, a slightly more selective solvent for the PS block, cylinders with significant microphase separation within the corona in the dry state were observed on the basis of TEM analysis. The use of acetone, which is slightly more selective for the PMMA block than the PS block, led to more distinct microphase separation to generate a "patchy" coronal morphology. Living crystallization-driven self-assembly studies in acetone allowed the formation of uniform cylindrical micelles and block comicelles of controlled length with "patchy" coronal segments by seeded growth methods.