Controlled synthesis of hyperbranched polymers by slow monomer addition toa core

Continuous, slow addition of AB(2) monomer (3,5-diiodophenylacetylene) to a solution of a multi-functional core results in high molecular weight hyper branched phenylacetylene polymers with narrow polydispersites. Control over the molecular weight (M-w = 8-90 kDa) was achieved by varying the monomer: core ratio from 17.5 to 560, At low ratios (<140, M-w = 49 kDa), monomodal molecular weight distributions were observed by SEC. A bimodal distribution was observed at higher ratios. Using an azobenzene functionalized core, in combination with SEC photodiode array detection, it was found that the cor e was not uniformly distributed over the entire bimodal distribution but ra ther predominantly found in the high molecular weight part of the distribut ion. The polydispersities of the hyperbranched polymers were found to decre ase with increasing degree of polymerization and with increasing core funct ionality. Our experimental results are in good qualitative agreement with c omputer simulations reported by Frey et al. and the theoretical work of Mul ler.