Control of macromolecular architecture of polyamides by poly-functional agents, 1 - Theoretic and experimental approaches to star-branched polyamides

In this first paper of the series, a statistical model for star-branched polycondensation of AB type monomers in the presence of a polyfunctional agent RAf was completely developed. The analytical expressions obtained for the number-average (DPn) and weight-average (DPw) degree of polymerization, and the dispersion index (D) for whole polymer species, linear and star macromolecular chains, were derived as a function of the conversion of the functional group of RAf. An important molecular parameter, mole fraction of star-branched polymer, was introduced. Numerical examples are reported on the relationship between molecular parameters and conversion of the functional group of RAf. It is illustrated that the molecular weight properties of the linear and starbranched polymers in the mixture of the products are very important factors for the application of this kind of polymeric materials. Polymerization of 6-aminocaproic acid was carried out in the presence of terephthalic (T2) and trimesic (T3) acids as tri- and bifunctional agents. The molecular weights calculated are in good agreement with those obtained by size exclusion chromatography (SEC).