Design of Versatile Clickable Hyperbranched Polymers by RAFT-SCVP and Multifunctionalization of Their Terminal Groups Using Azlactone Chemistry

A versatile and flexible azlactone clickable hyperbranched polymer (HBP) platform was prepared by reversible addition–fragmentation chain transfer self-condensing vinyl polymerization (RAFT-SCVP) followed by postpolymerization modifications (PPMs). RAFT-SCVP of a thiocarbonylthio methacrylic-based transmer and 2-( N,N -dimethylamino)ethyl methacrylate (DMAEMA) resulted in HBP-PDMAEMA, whose branched topology was thoroughly characterized using proton nuclear magnetic resonance ( 1 H NMR) spectroscopy, size exclusion chromatography (SEC) with multiangle light scattering, and viscometry detections. The HBP structure can be tailored through adjustment of the initial DMAEMA/transmer molar ratio: changing the initial molar ratio of DMAEMA/transmer from 10/1 to 1/1 results in an increase in the degree of branching (DB) from 0.08 to 0.22. Successive PPMs of these thiocarbonylthio-functionalized scaffolds were carried out to produce a versatile hyperbranched clickable platform containing azlactone terminal groups, as demonstrated by SEC using ultraviolet–visible (UV–vis) detection and Fourier transform infrared (FTIR) analyses. The efficiency of the aminolysis of thiocarbonylthio groups seems to be governed by their intrinsic reactivity, which depends on their structural environment. Either thiocarbonylthio groups participate in a chain transfer reaction and create branching points or they are not involved in the chain transfer reaction and remain as pendant groups. The efficient azlactone-amine click reaction of azlactone-functionalized HBP with various amines enables the elaboration of HBP with multiple functional terminal groups.