Networks Based on “Core-First” Star Polymers End-Linked Using a Degradable Ketal Cross-Linker: Synthesis, Characterization, and Cleavage

Abstract

Sequential group transfer polymerization of cross-linker, monomer (methyl methacrylate), and cross-linker again is used to prepare cleavable polymer networks based on interconnected “core-first” star polymers. By employing a degradable and a nondegradable cross-linker, four networks are prepared. While cleavage of the degradable cross-linker residues leads to complete polymer network dissolution, the degradation products do not always display the expected molecular weight features. These products are the expected in the case of the network prepared using only the degradable cross-linker (monomodal size distribution with expected low molecular weight) and also in the case of the network prepared using first the degradable and then the nondegradable cross-linker (bimodal size distribution including high molecular weight star polymers), but not so in the case of the network prepared using first the nondegradable and then the degradable cross-linker, where the expected high molecular weight star polymer component is missing due to star recombination after hydrolysis. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim