Synthesis of Polymer-Grafted Natural Rubbers by Radical Photopolymerization of Vinyl Monomers Initiated from the Rubber Chains

摘要

The synthesis of polymer-grafted natural rubbers (NRs) was considered through photopolymerization of vinyl monomers initiated from N,N-diethyldithiocarbamate groups previously introduced onto cis 1,4-polyisoprene units of NR chains. The development of the procedure was made with methyl methacrylate (NMA) as monomer. First, initiation of MMA photopolymerization was tested using a model molecule of the N,N-diethyldithiocarbamate-functionalized 1,4-polyisoprene unit to verify the feasibility of the procedure considered. Then, MMA polymerization was successfully initiated from N,N-diethyldithiocarbamate-functionalized NR backbone used as macroinitiator, and the conditions of grafting were optimized. It was shown that MMA grafting could occur either in monomer medium, in solution in toluene, and in latex medium, and that the quantities of homopolymer formed were still low. Thereafter, grafting studies were performed with other vinyl monomers (styrene, methacrylonitrile, acrylamide, acrylic acid) showing that grafting efficiency depends essentially on the nature of the monomer. The method developed here was shown particularly well adapted for the synthesis of polymer-grafted NR with monomers of low polarity.