Radical polymerization of diallylamine compounds: From quantum chemical modeling to controllable synthesis of high-molecular-weight polymers

We investigated the possibility to obtain high-molecular-weight (HMW) polymers from the monomers of the diallylamine (DAA) series using quantum chemical and experimental methods. Such monomers are known to polymerize into oligomeric products due to the reaction of the degradative chain transfer to the monomer. We studied potential energy profiles of the chain propagation and competing chain transfer reactions, viz., the free radical double bond addition and a-hydrogen radical abstraction, respectively, for a number of polymerization processes. Calculations were carried in the framework of the polarized continuum solvent model utilizing the procedure based on the semiempirical MNDO-PM3 background. It was found that the necessary condition for decreasing competitiveness of the chain transfer to the monomer is the availability of monomer molecules in only protonated form in the polymerizing system. Using these results, we developed the strategy for obtaining HMW polymers based on said monomers. We synthesized a monomer system (the equimolar salt of N,N-diallyl-N-methylamine and trifluoroacetic acid) that fully corresponds to such requirements. Novel HMW polymers were then synthesized by radical polymerization of this salt at soft conditions. We established that chain termination is controlled by the bimolecular mechanism. We showed that the degradative chain transfer transforms into the effective chain transfer. The mechanisms of the observed phenomena are discussed. (C) 2002 Wiley Periodicals, Inc.