Kinetic model of hyperbranched polymers formed by self-condensing vinyl polymerization of inimers and trifunctional cores with different reactivities in a continuous-stirred tank reactor

Abstract

A kinetic model is proposed to describe the formation of hyperbranched polymers, HBPs, by the self-condensing vinyl polymerization, SCVP, of inimers in a continuous stirred tank reactor, CSTR, with the addition of trifunctional cores. The dependence of the average degree of polymerization, DP, and the degree of branching, DB, on the Damköhler number, Da, is calculated by a generating function method. If the SCVP system has no core initiators, the flow in the CSTR may be stopped at a Da of approximately 0.5, which is caused by the formation of HBPs with ultrahigh molecular weights; then, the stable operating range becomes very narrow. The growth of HBPs in the SCVP can be retarded by adding the core with high reactivity into the CSTR. Therefore, formation of HBPs with ultrahigh molecular weights can be avoided even though the A groups are almost completely consumed at a high Da number. For example, the reduced weight-average DP is less than 1000 when the degree of conversion of the A group is 0.99, and only a few unreacted monomers remain in the product. The proposed model is useful for designing and optimizing a flow process for producing HBPs by the SCVP in a CSTR.