Low length dispersity fiber-like micelles from an A–B–A triblock copolymer with terminal crystallizable poly(ferrocenyldimethylsilane) segments via living crystallization-driven self-assembly†
Solution self-assembly of a linear ABA triblock copolymer with two terminal crystallizable poly(ferrocenyldimethylsilane) (PFS) core-forming “A” blocks and a central poly(dimethylsiloxane) (PDMS) corona-forming “B” block has been investigated. The low dispersity (D = 1.05) copolymer, PFS26-b-PDMS584-b-PFS26 (block ratio 1.0 : 22.5 : 1.0), was prepared through a combination of living anionic polymerization and end-to-end coupling. The block ratio and dispersity were established by a combination of MALDI-TOF mass spectrometry, 1H NMR, and GPC. Individual 1D fiber-like micelles with looped PDMS coronas were formed in mixed solvents of hexane and decane. Low length-dispersity fiber-like micelles of controlled length were prepared from short seed micelles of PFS26-b-PDMS584-b-PFS26 derived from sonication using the seeded growth method termed living crystallization-driven self-assembly. In addition, seeded growth of blends of both PFS26-b-PDMS584-b-PFS26 and PFS26 homopolymer and of PFS26-b-PDMS584-b-PFS26 and the analogous diblock copolymer PFS26-b-PDMS292 were also explored. Large aggregates with fiber-like protrusions were formed by spontaneous nucleation of the blends of PFS26-b-PDMS584-b-PFS26 and PFS26. High-aspect ratio ribbon-like micelles were formed by adding the blends of PFS26-b-PDMS584-b-PFS26 and PFS26 to the cylindrical PFS26-b-PDMS584-b-PFS26 seeds. In contrast, surprisingly, seeded growth of blends of PFS26-b-PDMS584-b-PFS26 and PFS26-b-PDMS292 or the individual components using seeds of either PFS26-b-PDMS584-b-PFS26 or PFS26-b-PDMS292 showed that growth was only detected in the case of matching of the seed and multiblock copolymer chemistries.