Solid-Supported Synthesis of Hyperbranched Polymer with Discrete Conjugated Units

Novel hyperbranched polymer poly(4-(5-hexynyloxy)-β,β-dibromostyrene) was synthesized by Pd-catalyzed cross-coupling reaction of 4-(5-hexynyloxy)-β,β-dibromostyrene in solution and using an aromatic polyamide solid support. According to the NMR data the degree of branching of the polymer obtained in solution without solid support was of 30—35%, while when using solid support the degree of branching increased to 60—65%. However, molecular weight of detached Poly-6 was lower that of the polymer obtained in solution. It seems that monomer molecules trapped in the vicinity of growing polymer chain by the polymeric support have more time to react with second bromine atoms of dibromovinyl groups, thus increasing branching of the polymer. Drop in molecular weight when using solid support is attributed to steric hindrance due to polymeric support, thus limiting the molecular weight of the attached polymer.