Crystallization-Driven Solution Self-Assembly of 渭-ABC Miktoarm Star Terpolymers with Core-Forming Polyferrocenylsilane Blocks
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- 作者：Adam Nunns ; George R. Whittell ; Mitchell A. Winnik ; Ian Manners
- 刊名：Macromolecules
- 出版年：2014
- 出版时间：December 9, 2014
- 年：2014
- 卷：47
- 期：23
- 页码：8420-8428
- 全文大小：481K
- ISSN：1520-5835
文摘
A comparative study of the solution self-assembly behavior of two polystyrene-arm-polyisoprene-arm-polyferrocenylsilane (渭-SIF) miktoarm star terpolymers of similar composition has been conducted: one with a short, atactic, noncrystallizable poly(ferrocenylethylmethylsilane) (PFEMS) block (渭-SIFa) and one with a short, crystallizable poly(ferrocenyldimethylsilane) (PFDMS) block (渭-SIFc). Both solvent composition and the amorphous/crystallizable nature of the polyferrocenylsilane (PFS) block exhibited a profound influence on the morphologies of the micelles obtained. In hexane, the formation of uniform spherical micelles with an amorphous, phase-mixed PS/PFS core was observed for both 渭-SIFa and 渭-SIFc. The introduction of cyclohexane (a theta-solvent for PS at 34.5 掳C) to give a 1:1 cyclohexane/hexane (v/v) solvent composition resulted in the formation of distorted spherical micelles with a core composed of phase-separated PS and PFS, for both 渭-SIFa and 渭-SIFc. Interestingly, the distorted spherical micelles formed from crystallizable 渭-SIFc evolved with time into elongated fiber-like structures with a phase-separated PS and PFDMS core, while the noncrystallizable counterpart, 渭-SIFa, remained as distorted spheres. It was found that in ethyl acetate, a good solvent for PI and PS, 渭-SIFa remained unimeric in solution, whereas 渭-SIFc formed cylindrical micelles composed of a crystalline PFDMS core and a phase-separated, patchy, PS and PI corona. Finally, seeded growth of 渭-SIFc from short, cylindrical PFDMS-b-PDMS seeds (PDMS = polydimethylsiloxane) was demonstrated, yielding B鈥揂鈥揃 block comicelles where outer segments derived from 渭-SIFc blocks bore a strong resemblance to that ultimately formed under conditions of homogeneous nucleation.