Catalysis by colloidal polymers in aqueous media

Crosslinked polymer latexes were prepared by emulsion copolymerization of e ither styrene or one of 14 different alkyl methacrylates and vinylbenzyl ch loride and converted to quaternary ammonium ion latexes by reaction with tr imethylamine or tributylamine. As catalytic colloidal media the cation exch ange latexes increased the rate decarboxylation of 6-nitrobenzisoxazole-3-c arboxylate up to 10 000 times and the rate of basic hydrolysis of p-nitroph enyl alkanoates up to 16 times in aqueous dispersions at room temperature. Latexes containing either 2ethylhexyl methacrylate as the inert component o f the polymer or tributylammonium ion active sites were most active. Cataly tic activity for the decarboxylation did not depend on particle size when t he diameter was <1 mum. Polyampholyte latexes containing 29/18 and 25/23 mo lar ratios of styrylmethyl(trimethyl)ammonium cations and methacrylate anio ns were colloidally stable in 4 M NaCl. Catalytic activity decreased with i ncreasing concentrations of NaCl in the dispersions, and all of the latexes except the polyampholytes coagulated at greater than or equal to 0.1 M NaC l. Dendrimers having one hydrophobic octyl group and one hydrophilic tri(et hylene glycol) methyl ether group on each tertiary amine end were prepared from commercial poly(propylene imine) dendrimers having eight and 32 primar y amine end groups and were converted to quaternary ammonium dendrimers by methyl iodide. After ion-exchange for chloride, the polycationic dendrimers increased the rate of the decarboxylation by 200-500 times the rate in pur e water. (C) 2001 Elsevier Science B.V. All rights reserved.