Solution self-assembly of ABC triblock terpolymers with a central crystallizable poly(ferrocenyldimethylsilane) core-forming segment

Abstract

The synthesis and solution self-assembly behavior of a range of linear ABC triblock terpolymers (triBCPs) with a central crystallizable poly(ferrocenyldimethylsilane) (PFDMS) core-forming segment have been explored. Two different PIP-b-PFDMS-b-PMMA triBCPs (1 and 2) (PIP = polyisoprene, PMMA = poly(methyl methacrylate) with different block ratios (1: 6.2:1.0:7.6; 2: 1.2:1.0:1.9) were investigated. TriBCP 1 was shown to form either cylinders or a mixed morphology of spheres and cylinders in various selective solvents, whereas triBCP 2 yielded either network structures or platelets. The PFDMS core-forming block of the spheres of 1 and network micelles of 2 formed in hexanes appeared to undergo slow crystallization, leading to the slow transformation to form cylinders and platelets, respectively. The self-assembly behaviour of a PS-b-PFDMS-b-PMVS triBCP (3, block ratio: 7.9:1.0:5.7; PS = polystyrene, PMVS = poly(methylvinylsiloxane)) was also examined in various solvents and yielded spheres and/or cylindrical micelles showing behavior reminiscent of 1. Despite their disparate self-assembly behavior, seeded growth "living crystallization-driven self-assembly" methods were successfully developed for 1-3 using short cylinders of PFDMS diBCPs as initiators to generate cylindrical B-A-B block co-micelles with controlled lengths. Moreover, a "patchy" coronal structure for the B segments was revealed by TEM and AFM analysis of dried samples.