Solid-supported synthesis of hyperbranched polymer with discrete conjugated units

Novel hyperbranched polymer poly(4-(5-hexynyloxy)-beta,beta-dibromostyrene was synthesized by Pd-catalyzed cross-coupling reaction of 4-(5-hexynyloxy) -beta,beta-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, molecul ar weight of detached Poly-6 was lower that of the polymer obtained in solu tion. II seems that monomer molecules trapped in the vicinity of growing po lymer chain by the polymeric support have more time to react with second br omine atoms of dibromovinyl groups, thus increasing branching of the polyme r. Drop in molecular weight when using solid support is attributed to steri c hindrance due to polymeric support, thus limiting the molecular weight of the attached polymer.