Novel Degradable Polymer Networks Containing Acetal Components and Well-Defined Backbones

Abstract

A novel copolymer network was successfully prepared by combining the reversible addition–fragmentation chain-transfer polymerization (RAFT) and addition reaction between hydroxyl and vinyloxy groups. 2-Hydroxyethyl methacrylate (HEMA) and methyl methacrylate (MMA) were copolymerized in 1,4-dioxane with 2,2′-azobisisobutyronitrile as initiator and 2-(ethoxycarbonyl)prop-2-yl dithiobenzoate as a RAFT agent. The molecular weight of poly(HEMA-co-MMA) was well controlled and the polydispersity was low. The hydroxyl group from the HEMA unit in the copolymer underwent an addition reaction with 1,4-cyclohexanedimethanol divinyl ether in the presence of pyridinium p-toluenesulfonate, generating a copolymer network with an acetal component in the crosslinking segment. The crosslinking time depended on the molar ratio of HEMA and MMA in the poly(HEMA-co-MMA). After being treated in strong acid, the copolymer network was able to be degraded owing to the acetal structure, but the backbone chains of poly(HEMA-co-MMA) remained intact.

Acid-degradable polymers for drug delivery: a decade of innovation

“…30 More recently, Sui et al prepared an acetal-based polymer network by combining reversible addition-fragmentation chain-transfer polymerization (RAFT) with addition reactions by reacting the hydroxyl pendant groups of the polymer with 1,4-cyclohexanedimethanol divinyl ether. 31 Chatterjee and Ramakrishna reported the synthesis of hyperbranched polyacetals via a melt transacetalization polymerization process of an AB 2 monomer bearing a single hydroxyl group and a dialkyl acetal. 32 The bulk degradation rates of these hyperbranched polyacetals under mildly acidic pH (pH = 4) revealed the strong dependence of the degradation rates on the nature of peripheral alkyl substituents.…”

Acid degradable poly(vinylcaprolactam)-based nanogels with ketal linkages for drug delivery

“…23 Recently, Sui et al synthesized an acetal-based polymer nanogel by reaction of the hydroxyl pendant groups of the polymer and 1,4-cyclohexanedimethanol divinyl ether after the reversible addition-fragmentation chain-transfer polymerization (RAFT). 24 The release rate of the loaded drug molecules from the nanogels can be modulated by the pH of the environment. Zhong et al prepared core-crosslinked pH-sensitive degradable nanogels, where acid-labile acetal and photo-crossslinkable acryloyl groups existed in the hydrophobic polycarbonate block for intracellular paclitaxel (PTX) release.…”

Synthesis and Characterization of End-Linked Amphiphilic Copolymer Conetworks Based on a Novel Bifunctional Cleavable Chain Transfer Agent

“…In particular, those examples included microgels, 37 nanogels, 39,40 and a randomly cross-linked macroscopic gel. 38 Furthermore, in all four cases, the labile acetal group was introduced to the polymer structure through the cross-linker. The present study provides the first examples of polymers synthesized via RAFT polymerization in which the labile acetal group was introduced through the chain transfer agent (CTA).…”

“…There are only few examples of polymers synthesized via RAFT polymerization, bearing acetal groups, − none of which was an APCN. In particular, those examples included microgels, nanogels, , and a randomly cross-linked macroscopic gel .…”

“…There are only few examples of polymers synthesized via RAFT polymerization, bearing acetal groups, − none of which was an APCN. In particular, those examples included microgels, nanogels, , and a randomly cross-linked macroscopic gel . Furthermore, in all four cases, the labile acetal group was introduced to the polymer structure through the cross-linker.…”