Catalysis by Polymer Latexes and Dendrimers

摘要

Polymer latexes and dendrimers have been synthesized and tested as catalysts for basic hydrolysis of CW simulants. The latexes were made from methacrylic esters or styrene and functional monomers, and they contained quaternary ammonium groups as ion exchange sites for reagents, such as hydroxide ion, and catalysts, such as o-iodosobenzoate ion (IBA). By use of an ion exchange model for the kinetics, the rates of hydrolysis of p-nitrophenyl esters in the latexes were shown to depend mainly on the ability of the latex to sorb the organic reactant from water. The catalysts were active for hydrolysis of organophosphates in aqueous NaOH at phosphate concentrations as high as 0.25 M. Latexes that were stable in the presence of high concentrations of electrolytes were created by use of a poly(ethylene oxide)-containing monomer and by copolymer modifications leading to cross-linked polyampholytes. The polyampholytes were stable indefinitely and were catalytically active even in 4 M NaCl solution. Metal complexes of poly(propylene imine) dendrimers were weakly active catalysts for the hydrolyses of p-nitrophenyl diphenyl phosphate and of bis(p-nitrophenyl phosphate). A new family of dendrimers having alternating amine and ether generations was synthesized. Poly(propylene imine) dendrimers having 8,32, and 64 primary amine end groups were converted to tertiary amines and to a variety of quaternary ammonium salts. Some had both hydrophobic octyl and hydrophilic triethylene glycol methyl ether chains on each end. Applications of the new dendrimers to catalysis are planned.