Synthesis and micellization behavior of Janus H-shaped A2BC2 terpolymers

The synthesis of a series of H-shaped A(2)BC(2) terpolymers (Janus-H terpolymers), where A is poly(dimethylsiloxane) (PDMS), B polybutadiene (PBd), and C polystyrene (PS), is presented. The synthetic approach involves (a) the selective reaction of lithium PDMS alkolate with the two chlorosilane groups of the heterofunctional linking agent [(chloromethylphenyl)ethyl]methyldichlorosilane (CMPEMDS) and (b) the linking reaction of the benzyl chloride group, which remained intact, with the living star (PS)(2)PBd-DPHLi. The synthesis of the living miktoarm star is achieved by (a) the selective reaction of the PSLi chains with the two chlorines of the linking reagent 4-(dichloromethylsilyl)diphenylethylene (DCMSDPE), (b) the addition of sec-BuLi to the double bond of the DPE group, and (c) the polymerization of Bd, followed by end-capping of the living end with one monomeric unit of DPE. The micellization behavior of the Janus-H terpolymers was studied in methyl ethyl ketone, a selective solvent for the outer branches of the terpolymers, PS, and PDMS. The complexity of the architecture along with "microdomain segregation" phenomena, also observed, led to the formation of unimolecular micelles or micelles with very low degrees of association.