Directing the self-assembly of semiconducting copolymers: The consequences of grafting linear or hyperbranched polyether side chains

摘要

The synthesis and self-assembly of novel semiconducting rod-coil type graft block copolymers based on poly(para-phenylene vinylene) (PPV) copolymers is presented, focusing on the ordering effect of linear versus hyperbranched side chains. Using an additional reactive ester block, highly polar, linear poly(ethylene glycol), and hyperbranched polyglycerol side chains are attached in a grafting-to approach. Remarkably, the resulting novel semiconducting graft copolymers with polyether side chains show different solubility and side-chain directed self-assembly behavior in various solvents, e.g., cylindrical or spherical superstructures in the size range of 10 to 120 nm, as shown by TEM. By adjusting the molecular weight and the topology of the polyether segments, self-assembly into defined superstructures can be achieved, which is important for the efficient charge transport in potential electronic applications. The linkage of linear or hyperbranched polyether chains modifies the self-assembly of rod (PPV)-coil block copolymers. Either cylindrical or spherical micelles were obtained, depending on the molecular weight and/or the geometrical structure of the polar side chains. The micelles were investigated by transmission electron microscopy.