The effect in the RAFT polymerization of two oligo(ethylene glycol) methacrylates when the CTA 4-cyano-4-(propylthiocarbonothioylthio) pentanoic acid is auto-hydrolyzed to its corresponding amide

Abstract

The effect on the RAFT polymerization of di(ethylene glycol) methyl ether methacrylate (DEGMA) and oligo(ethylene glycol) methyl ether methacrylates M_n = 300 g mol⁻¹(OEGMA) was studied when the R leaving group of the chain transfer agent (CTA) 4-cyano-4-(propylsulfanylthiocarbonyl)sulfanyl pentanoic acid (CPP) changes due to its partial auto-hydrolysis of the nitrile group to form the corresponding amide, therefore a different CTA (APP). In the best of our knowledge, this partial hydrolysis of this compound had not been reported. Characterization of all compounds and polymers was carried out by FTIR-ATR, NMR, DSC and TGA. Monomer conversion was evaluated by ¹H NMR; M_n, M_w and Đ were obtained by GPC; finally, their thermo-responsive character was evaluated. By using CTA in polymer synthesis, average molecular weights were lower than by conventional free radical polymerization (FRP), when CPP and APP mediated polymerizations were compared, there were differences in rate polymerization of DEGMA resulting in different molecular weights and Đ; however in the RAFT polymerization of OEGMA similar products were obtained. Finally, their thermo-responsive character was evaluated, in which cloud point temperatures for PDEGMA and POEGMA using APP were observed between 23 and 24 and 65–68 °C respectively.

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