Cobalt-mediated catalytic chain-transfer polymerization (CCTP) in water and water/alcohol solution

This article describes the use of cobalt-mediated catalytic chain transfer in aqueous solution under fed conditions for the preparation of macromonomers of acidic, hydroxy, and zwitterionic functional monomers. Use of a batch reaction leads to hydrolysis of catalyst, a mixture of mechanisms and poor control of the reaction. A feed process is described that adds catalyst as a solution in monomer over the course of the reaction. The feed process is applied to a range of monomers of methacrylic acid (2), 2-aminoethyl methacrylate hydrochloride (3), 2-hydroxyethyl methacrylate (4), 2-methacryloxyethyl phosphoryl choline (5), glycerol monomethyl methacrylate (6), and 3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-D-glucofuranose (7). Use of the feed process for water-soluble monomers in conjunction with 1 as a catalytic chain-transfer agent gives high-conversion, > 90%, water-soluble macromonomers. The number-average molecular mass M-n was determined by integration of the H-1 NMR spectrum comparing the vinylic end group with the remainder of the backbone. Pseudo-Mayo plots were constructed by measuring the M, at high conversion as a function of [monomer]/[catalyst] to give observed chain-transfer constants of 1120, 958, and 1058 for 4, 6, and 2, respectively. All products were obtained as relatively high-solid, homogeneous, low-viscosity aqueous solutions. (C) 2001 John Wiley & Sons, Inc.