Molecular weight distribution of hyperbranched polymers generated by self-condensing vinyl polymerization in presence of a multifunctional initiator

The molecular weight distribution (MWD) is derived for polymers generated b y self-condensing vinyl polymerization (SCVP) of a monomer having a vinyl a nd an initiator group ("inimer") in the presence of a multifunctional initi ator. If the monomer is added slowly to the initiator solution (semi-batch process), this leads to hyperbranched polymers with a multifunctional core. If monomer and initiator are mixed simultaneously (batch process), even at vinyl group conversions as high as 99%, the total MWD consists of polymers which have grown via reactions between inimer molecules (i.e., the normal SCVP process) and those which have reacted with the initiator. Consequently , the weight distribution, w(M), is bimodal. However, the z-distribution, z (M), equivalent to the "GPC distribution", w(log M) vs log M, is unimodal.