Novel cationic macromonomers by living anionic polymerization of (dimethylamino)ethyl methacrylate

Water-soluble cationic macromonomers of (dimethylamino)ethyl methacrylate ( DMAEMA) with terminal diallylmethylammonium or allylmethylphenylammonium gr oup were synthesized by nitrogen anion (nitroanion) initiated living anioni c polymerization of DMAEMA and subsequent quaternization. The initiators, l ithium diallyamide and lithium allylphenylamide, were prepared by the react ion of corresponding N-substituted allylamine with butyllithium. The substi tuents on the nitroanion had a significant effect on the initiation efficie ncy. The initiator efficiencies of lithium allylamide, diallylamide, and al lylphenylamide increased by the order 0 < 25% < 79% at -78 degreesC. The lo w initiator efficiency of lithium diallylamide was due to the reaction of t he nitroanion with carbonyl groups in the monomer and polymer and could not be improved by optimizing polymerization conditions. A capping method usin g dimethylacrylamide (DMA) or tert-butyl methacrylate (tBMA) was then devel oped to modify the lithium diallylamide and thereby increased initiator eff iciency. The DMA or tBMA. capped lithium diallylamide had an initiator effi ciency higher than 0.90, producing polymers with predicted molecular weight and nearly monodispersed polydispersity. Subsequent quaternization with CH 3I and dimethyl sulfate converted the polymer into cationic macromonomers w ith diallylmethylammonium or allylmethylphenylammonium terminal groups, whi ch are readily copolymerizable with other vinyl monomers such as acrylamide and vinylformamide.