Influence of helical cellulose Tris(3,5-dimethylphenylcarbamate)s on the radical polymerization of methyl Methacrylate: Efficient control on molecular weight and polymerization kinetics

In order to explore the influence of helical polymers on the polymerization behavior of methacrylate monomers, the helical cellulose tris(3,5-dimethylphenylcarbamate)s (CDMPC) was synthesized via “one-pot” procedure. Then a series of poly(methyl methacrylate)s (PMMAs) were synthesized through radical polymerization in the presence of CDMPC. The structure and properties of the resulting CDMPC and PMMAs were characterized by 1 H NMR, GPC, DSC and nitrogen absorption, respectively. The influence of the feed ratio of CDMPC to MMA and initiator concentration on the properties of PMMAs was carefully investigated. Interestingly, the PMMAs synthesized in the presence of CDMPC exhibited much higher molecular weight with a narrower distribution than those of PMMAs obtained without CDMPC. The former PMMAs possessed much higher content of chain segments from coupling termination than those from disproportionation termination. It indicated that the chain propagation was probably significantly accelerated with the modulation of CDMPC and the polymerization was then effectively ended via coupling termination, which agreed well with the observation in the real-time exothermic monitoring of the polymerization process. Furthermore, the end-group structure was investigated based on the structure of MMA oligomers synthesized in the presence of CDMPC, to gain a better understanding of the related mechanism. The helical CDMPC exhibited an efficient control on the molecular weight, its distribution and polymerization kinetics of PMMAs in the radical system, providing a valuable strategy for modulation of the radical polymerization of methacrylates. The influence of CDMPC on the tacticity of PMMAs was further examined.