Synthesis and modification of thermoresponsive poly(oligo(ethylene glycol) methacrylate) via catalytic chain transfer polymerization and thiol–ene Michael addition

Abstract

Various poly(oligo(ethylene glycol) methyl ether methacrylate)s (POEGMEMAs) have been prepared by Catalytic Chain Transfer Polymerization (CCTP) using a range of OEGMEMA monomers (molecular weight from 180 to 1100 g mol À1 ). The chain transfer constants of bis(boron difluorodimethylglyoximate) cobalt(II) (CoBF) were determined and are reported for each monomer. The copolymerization of POEGMEMA (M n ¼ 475 g mol À1 ) with diethylene glycol methyl ether methacrylate (DEGMEMA) yielded thermoresponsive polymers. The lower critical solution temperatures (LCSTs) of the polymer chains can be tuned by the copolymer composition over the range 30 C to 95 C. In addition, the presence of the vinylic end-group, characteristic of CCT polymerization, provided further scope for post-synthetic modification via thiol-ene click chemistry, through nucleophilic Michael addition with various functional thiol compounds such as 2mercaptoethanol, 3-mercaptopropionic acid, benzyl mercaptan and 1-dodecanethiol. The thiol-ene reaction was rigorously tested, optimized and characterized in this study in terms of solvents and most importantly the choice of the catalyst: dimethyl phenyl phosphine, tertiary amine or hexylamine. The optimum conditions reported allow near-quantitative functionalization of these macromonomers without significant side reactions. The effect of the end-group on the LCST has also been investigated, as well as thermal stability temperature of the copolymers.

Novel thermosensitive telechelic PEGs with antioxidant activity: synthesis, molecular properties and conformational behaviour

“…Modifying highly soluble polymers such as pMeOx, pHPMA, PEG, starches, or dextran with hydrophobic or thermosensitive moieties lowers their LCST values. 28,29,32,34,36,[38][39][40][41][42][43][44][45][46][47][48][49][50][51][52] Polymers architecture and grafting density might have also influence on thermosensitive properties. 48,51,[53][54][55] In the majority of studies on polymers with LCST behaviour, the hydrophobic or thermosensitive modifier possesses no biological activity.…”

The preparation and physical properties of polysulfide-based elastomers through one-pot thiol-ene click reaction

“…As observed from in Figure 6, all of the obtained polysulfide elastomers are thermally stable with 5% weight loss at temperatures around 290°C despite of different dosage of bisphenol-A diacrylate resin used, indicating higher thermal stability of bisphenol-A diacrylate structure than polysulfide units. These results can be explained by the presence of the C-O bond, more stable at high temperature than an S-S or C-S bond as indicated by the enthalpy of dissociation [29]. However, as a comparison, polysulfide elastomer cured by MnO 2 displayed 5% weight loss at temperature of 216°C.…”

Glycopolymers via Post‐Polymerization Modification Techniques

“…It is well known that activated vinyl groups can undergo hetero-Michael reaction with thiols. This reaction has been termed base-catalyzed thiol-ene click reaction [88,89]. Moreover, the sugar azides can be clicked onto the polymer scaffold before or after the thiol-ene click chemistry has been performed.…”