Star-shaped polymers by metal-catalyzed living radical polymerization. 1. Design of Ru(II)-based systems and divinyl linking agents

Star-shaped polymers that consist of well-defined poly(methyl methacrylate) [poly(MMA)] arms and a microgel core of a divinyl compound were prepared i n high yield with the RuCl2(PPh3)(3)-catalyzed living radical polymerizatio n followed by direct in-situ polymer linking reactions with divinyl compoun ds. In typical examples, these star-shaped polymers had the arm number (f) of 10-30 and (M) over bar (w)- (star) > 10(5). The following factors were e ffective in the star-shaped polymer formation: (a) a monofunctionalized chl oride initiator; (b) a linking agent with a soft aliphatic or a rigid long aromatic spacer between the two methacryloyl groups.