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

Abstract

A novel bifunctional bis(hemiacetal ester) chain transfer agent (CTA), 1,2-bis[1-(4-cyano-4-methyl-1-oxo-4-(phenylcarbonothioylthio)butanoxy)ethoxy]ethane (CMPTBEE), appropriate for the reversible addition− fragmentation chain transfer (RAFT) polymerization of methacrylate monomers, was successfully synthesized and used for the preparation of a family of 10 hydrolyzable endlinked polymer (co)networks. The family comprised three methyl methacrylate (MMA) homopolymer networks with different degrees of polymerization, 100, 150, and 200, and seven end-linked amphiphilic polymer conetworks of MMA and 2-(dimethylamino)ethyl methacrylate (DMAEMA) with a constant overall degree of polymerization equal to 200 but various compositions and architectures. The agreement of the experimentally measured molecular weights with the theoretically expected ones and the low molecular weight dispersities of the linear precursors to the (co)networks indicated successful control of the polymerization. All (co)networks were characterized in terms of their sol fraction and in terms of their degree of swelling in THF. The value of the former was found in the range between 4 and 50%, whereas that of the latter was around 13%. The presence of the hemiacetal ester groups allowed the hydrolysis of the most hydrophilic, DMAEMA-rich conetworks. The resistance to hydrolysis of the other (co)networks could be attributed to the large hydrophobic blocks surrounding and protecting from hydrolysis the hemiacetal ester groups of the CTA residue in the conetworks.

Degradable/cytocompatible and pH responsive amphiphilic conetwork gels based on agarose-graft copolymers and polycaprolactone

“…APCN gel is a modified version of a hydrogel which is useful for the controlled release of both hydrophilic and hydrophobic drugs. 28,29 These APCNs are degradable due to the hydrolytic instability of the group transfer initiator or chain transfer agent (containing two cleavable hemiacetal ester groups) used for their synthesis. 24,25 This is because the release of drugs is generally governed by diffusion in a swollen polymer hydrogel having intrinsically high water affinity.…”

Investigations on diffusion limitations of biocatalyzed reactions in amphiphilic polymer conetworks in organic solvents

“…Other APCNs can even be swollen in water and perfluorinated solvents (Bruns and Tiller, ). Besides commercial applications many other examples of the high performance of APCNs are described in the literature, ranging from tubular networks for insulin delivery (Kennedy et al, ), their use as phase transfer matrix for enzymatic catalyzed conversions in organic solvents (Savin et al, ) and in supercritical CO 2 (Bruns et al, ), optical biochemical sensors for peroxide detection (Hanko et al, , ), biomimetic material for synthesis of biological membranes (Taubert et al, ), for release of antimicrobial surfactants (Tiller et al, ) for pH‐sensitive drug delivery (Colinet et al, ; Liu et al, ), chemically cleavable conetworks (Rikkou‐Kalourkoti and Patrickios, ), and for chiral separation (Tobis et al, , ). An overview on this topic is given by Erdodi and Kennedy ().…”

Self‐Sealing and Puncture Resistant Breathable Membranes for Water‐Evaporation Applications

“…The plant Aristolochia macrophylla , a North American liana, has a mechanism to mechanically close defects. The self-sealing membrane consisted of a waterproof and breathable, non-porous poly(ether ester) multi-block copolymer membrane (PEE; Sympatex membrane) [ 2,22 ] onto which an amphiphilic polymer co-network (APCN) [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] was polymerized. Inspired by this phenomenon, Speck and co-workers developed an airtight pneumatic membrane (as used, e.g., in infl atable boats) that is capable to close punctures by the expansion of a polyurethane-foam.…”

“…The self-sealing membrane consisted of a waterproof and breathable, non-porous poly(ether ester) multi-block copolymer membrane (PEE; Sympatex membrane) [ 2,22 ] onto which an amphiphilic polymer co-network (APCN) [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] was polymerized. The self-sealing membrane consisted of a waterproof and breathable, non-porous poly(ether ester) multi-block copolymer membrane (PEE; Sympatex membrane) [ 2,22 ] onto which an amphiphilic polymer co-network (APCN) [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38] was polymerized.…”