Use of oxyanion-initiated polymerization for the synthesis of amine methacrylate-based homopolymers and block copolymers

Abstract

A series of amine methacrylate homopolymers, diblock copolymers and triblock copolymers has been synthesized using oxyanion-initiated polymerization. The amine methacrylate monomers of interest were 2-(dimethylamino)ethyl methacrylate (DMA), 2-(diethylamino)ethyl methacrylate (DEA), 2-(N-morpholino)ethyl methacrylate (MEMA) and t-(butylamino)ethyl methacrylate (BAE). In most experiments potassium benzyl alcoholate was utilized as an initiator since this facilitated both UV GPC studies and end group analysis using 1H NMR spectroscopy. For the homopolymerization of DMA, molecular weights increased linearly with conversion and polydispersities were reasonably narrow. Together with successful block copolymer formation, this constitutes good evidence for the “living” character of oxyanion-initiated polymerization. Most of the diblocks are novel copolymers and selected copolymers undergo reversible temperature-induced micellization in aqueous media. NMR studies confirmed that the DMA residues of a DMA–BAE diblock copolymer could be selectively quaternized using a stoichiometric amount of methyl iodide under mild conditions. Finally, shell cross-linked micelles could be prepared from ABC triblock copolymers. The C block formed the core, the B block contained cross-linkable residues and the A block acted as a steric stabilizer and prevented inter-micelle aggregation even when the cross-linking chemistry was carried out at high copolymer concentrations.