Self-assembled nanostructure of a novel coil-rod diblock copolymer in dilute solution

A novel narrowly distributed rod-coil diblock copolymer, poly(styrene-block-(2,5-bis[4-methoxy phenyl]oxycarbonyl)styrene) (PS-b-PMPCS), was synthesized by 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) mediated living free radical polymerization. The rodlike PMPCS block is a mesogen-jacked liquid crystalline polymer and is soluble in p-xylene at temperatures higher than 100 degreesC. When a PS-b-PMPCS dilute solution is cooled, the copolymer chains can self-assemble into a core-shell nanostructure. The temperature-induced self-assembly was studied. We showed, for the first time, that instead of a neutron scattering, a combination of static and dynamic laser light scattering results could also lead to the core radius (R-c) and the shell thickness (DeltaR). Using this novel method, we found that when more chains were assembled into the nanostructure, R-c remained as a constant, close to the contour length of the PMPCS block, but the shell became thicker, indicating that the attraction between the insoluble rigid rodlike PMPCS blocks led to their insertion into the core, while the repulsion between the soluble coillike PS blocks forced them to stretch in the shell.