Synthesis and Characterization of Polymer Networks and Star Polymers Containing a Novel, Hydrolyzable Acetal-Based Dimethacrylate Cross-Linker

Abstract

An acid-labile dimethacrylate acetal cross-linker, di(methacryloyloxy-1-ethoxy)methane (DMOEM), was synthesized by the reaction of 2-hydroxyethyl methacrylate and paraformaldehyde using p-toluenesulfonic acid and toluene as catalyst and solvent, respectively. Group transfer polymerization was employed to use this cross-linker in the preparation of nine hydrolyzable polymer structures: one neat cross-linker network, one randomly cross-linked network of methyl methacrylate (MMA), and seven star-shaped polymers of MMA. Gel permeation chromatography (GPC) in tetrahydrofuran (THF) confirmed the narrow molecular weight distributions of the linear polymer precursors to the stars and demonstrated the increase in molecular weight upon the addition of cross-linker for the formation of star-shaped polymers. Characterization of the star polymers in THF using static light scattering and GPC showed that the molecular weights and the number of arms of each star polymer increased with an increase in the molar ratio of cross-linker to initiator and with a decrease in the molar ratio of monomer to initiator. The star polymers with DMOEM cores bore a smaller number of arms than those cross-linked with the non-hydrolyzable commercial cross-linker ethylene glycol dimethacrylate due to the bulkier structure of DMOEM. All DMOEM-containing polymer networks and star polymers were completely hydrolyzed within 48 h using hydrochloric acid in THF.

Recent Advances in Star Polymer Design: Degradability and the Potential for Drug Delivery

“…An example of this is shown by the work of Patrickios and coworkers [47][48][49] who, in addition to synthesizing degradable ester-based cross-linkers, also utilized acid-labile siloxane and acetal groups to synthesize a dimethyldi(methacryloyloxy-1-ethoxy)silane (4) and di(methacryloyloxy-1-ethoxy)methane (5) cross-linker, respectively. These degradable cross-linkers were subsequently polymerized under group transfer polymerization conditions to yield CCS polymers with degradable cores.…”

Facile one‐shot synthesis of functional star‐shaped polymers by domino‐type living cationic copolymerization

“…Functional core cross‐linked star‐shaped (CCS) polymers, which consist of multiple linear arm chains radiating from a central microgel core, have enormous potential as intelligent materials for a wide range of applications, including biomedical imaging, as drug carriers, environmental protectors, nanocatalysts, and smart films . Substantial progress has been made by the recent advance in controlled/living radical polymerization, which has allowed the synthesis of a range of functional CCS polymers.…”

Self-reporting dynamic covalent polycarbonate networks

“…15 Within this context, a broad range of chemical concepts have been investigated, such as photoreversible olefin cycloadditions, 16 carbene dimerization, 17 sulfide coupling 18 and thermally cleavable alkoxyamines. 19 Thereby, Diels-Alder (DA) and Hetero-Diels-Alder (HDA) chemistry are highly interesting and by far the most widely investigated reversible linkage mechanisms. This is due to the availability of a broad variety of dienes and dienophiles that can potentially be utilized, allowing the fine-tuning of the temperature range in which the bonding and debonding takes place.…”