Synthesis of water-soluble statistical copolymers and terpolymers containing pendent oligo(ethylene glycol derivatives)

A series of water-soluble pendent oligo(ethylene glycol)-based statistical copolymers and terpolymers were synthesised using group transfer polymerisa tion (GTP). More specifically, oligo(ethylene glycol) monomethyl ether mono methacrylate (OEGMA) macromonomers containing 6, 21 or 44 ethylene glycol u nits were copolymerised with either benzyl methacrylate (BzMA), 2-(dimethyl amino)ethyl methacrylate (DMAEMA) or tetrahydropyranyl methacrylate (THPMA) to give statistical copolymers. The analogous terpolymers were obtained by copolymerising the oligo(ethylene glycol) monomethyl ether monomethacrylat es with n-butyl methacrylate (nBuMA) and either BzMA or DMAEMA. Gel permeat ion chromatography was used to determine copolymer molecular weights and po lydispersities, while proton NMR spectroscopy was used to assess their comp ositions. In all cases, the final copolymers were near-monodisperse (M-w/M- n's < 1.2) and good molecular weight control was achieved. The BzMA-contain ing copolymers were deprotected via catalytic hydrogenolysis to selectively remove the benzyl groups, giving polymers containing carboxylic acid group s. Similarly, the THPMA-containing polymers were deprotected by acidic hydr olysis to remove the tetrahydropyranyl groups, also resulting in acidic sta tistical polymers. Comparison of the degrees of deprotection achieved using the BzMA and THPMA protected monomers suggests that THP is the preferred p rotecting group since it is removed quantitatively regardless of the copoly mer composition. In contrast, incomplete deprotection was obtained for the copolymers containing more than 67 mol% BzMA. (C) 1999 Elsevier Science Ltd . All rights reserved.