Intramolecular cyclization in hyperbranched star copolymers via one-pot Am+Bn+C1 step-growth polymerization resulting in decreased cyclic defect

Abstract

Hyperbranched star copolymers are important soft materials that have been employed for aqueous self-assembly and bioapplication, but their one-pot one-batch synthesis strategy and relevant topology are rarely discussed. In this contribution, we produce hyperbranched star poly(vinyl ether ester)s (mPEG-hb-PVEEs) amphiphiles with multimodal molecular weight distribution via one-pot one-batch Am+Bn+C1 (m ≥ 2, n ≥ 3) step-growth polymerization. Based on the topological analysis of these hyperbranched star copolymers, a convenient expression of the number ratio of monomeric structural units (NA/NB) is deduced to describe the cyclic defect of intramolecular cyclization only by using proton nuclear magnetic resonance spectroscopy. The introduction of long-chain terminators and the change in the molar feed ratio of A2:B3:C1 considerably affect the NA/NB so as to give rise to increased influence of number of macromolecules and decreased influence of intramolecular cyclization, which are then responsible for an aqueous self-assembly behavior of mPEG-hb-PVEEs amphiphiles. Overall, this study opens new possibilities for the precise description of intramolecular cyclization and controllable synthesis of hyperbranched star copolymers via one-pot Am+Bn+C1 step-growth polymerization.