Study of polycondensations of AB_x-type monomers with A multifunctional core RBf - The degree of polymerization and the polydispersity index

The polycondensation of AB_x-type monomers with a multifunctional core RB_f was investigated in this paper. A new method of using the extent of reaction (p) to evaluate the number average degrees of polymerization (x_n), weight average degrees of polymerization (x_w) and polydispersity index (D) of hyperbranched polymers of this polycondensation system was proposed, giving the relationship between them and the calculation formulas. The results show that, both x_n and x_w increase with the increase of p, and the x_n equals to the theoretical value when p is equal to 1. The presence of a small amount of multifunctional core molecules in the polycondensation systems leads to a marked reduction of D. And the greater the number of functional groups in the core moiety, the narrower the final molecular weight distribution of the hyperbranched polymers.