Hybrid dendritic-linear graft copolymers: Steric considerations in `coupling to' approach

A `coupling to' approach was developed for the synthesis of hybrid dendritic-linear block copolymers. Frechet-type polyether dendrons were prepared by the convergent growth approach and coupled with well-defined functionalized polystyrene backbones prepared by living free radical procedures. The subtle interplay between the degree of functionalization present in the backbone and the size of the dendritic fragment led to incomplete reactions as steric crowding along the backbone increased. This resulted in globular hybrid macromolecules instead of the extended rods typically formed from the polymerization of dendritic macromonomers.