Cylindrical Micelles with “Patchy” Coronas\nfrom the Crystallization-Driven Self-Assembly of ABC Triblock Terpolymers\nwith a Crystallizable Central Polyferrocenyldimethylsilane Segment

Abstract

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