Cesare Guaita

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 RA f was completely developed. The analytical expression obtained for the number-average (DP n ) and weight-average (DP w ) 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 RA f . 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 RA f . It is illustrated that the molecular weight properties of the linear and star-branched 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).