Hyperbranched Polymers with High Degrees of Branching and Low Dispersity Values: Pushing the Limits of Thiol–Yne Chemistry

Abstract

We propose a versatile approach to the production of hyperbranched polymers with high degrees of branching and low dispersity values (Đ), involving slow monomer addition of a thiol/yne monomer to multifunctional core molecules in the presence of photoinitiator and under UV irradiation. The small thiol/yne monomer was synthesized via 1-ethyl-3-(3-(dimethylamino)propyl)carbodiimide hydrochloride (EDC·HCl) esterification, and batch polymerizations were performed at varying concentrations. The batch thiol–yne polymerizations had fast reaction kinetics and large dispersity values that increased with increasing concentration. Introduction of monomer by slow addition to a multifunctional alkyne core (tri(prop-2-yn-1-yl) 1,3,5-benzenetricarboxylate) or alkene core (triallyl 1,3,5-benzenetricarboxylate) was found to lower dispersity at monomer concentrations of 0.5–2.0 M. Degrees of branching were determined by 1H NMR spectroscopy to be greater than 0.8 in most cases. Increasing the fraction of core molecule was f...