Controlled radical polymerization catalyzed by CuCl/BDE complex in water medium. II. Polymerization of methyl methacrylate and formation of PMMA with bimodal molecular weight distribution

Abstract

ABSTRACT:The emulsion polymerization of MMA was explored for the BDE/CuCl coordinated catalyst. The M n of PMMA linearly increased both with increasing the monomer conversion and the proceeding polymerization time, which means that the MMA polymerized in "living"/controlled characters with zero order kinetics under BDE/CuCl-catalyzed emulsion conditions. The apparent polymerization rate constants of MMA were k app[MMA]1.8M ϭ 0.228 mol/min at 50°C, respectively. Slight differences of polymerization results were obtained when emulsifier lauryl phosphate (ADP) and Polyoxyethylene nonyl phenyl ether (OP-10) were adapted in the polymerization. Based on the "coordinated radical cage" mechanism proposed particularly to the BDE/CuCl catalyzed polymerization, reversible equilibrium between common free radical and the coordinated "living" species should exist in this system. Increasing the amount of catalyst must affect the fast equilibrium between those two species, thus, also affecting the relative content in the emulsion circumstance. Therefore, PMMA, with bimodal molecular weight distribution, was achieved through this approach. The formation of PMMA with bimodal distribution was affected by concentration of catalyst and polymerization temperature.

Controlled Bimodal Molecular‐Weight‐Distribution Polymers: Facile Synthesis by RAFT Polymerization

“…Lenzi and co‐workers9 prepared bimodal MWD polymer resins of polystyrene and poly(butyl acrylate) by using nitroxide‐mediated polymerization combined with conventional free radical polymerization. Wan and co‐workers10 reported the formation of bimodal MWD poly(methyl methacrylate) by using controlled radical polymerization catalyzed by a CuCl/bis(2‐dimethyl‐aminoethyl) ether (BDE) complex in an aqueous medium. Unfortunately, these reports with LRP methods have not overcome the drawbacks mentioned above; that is, they failed to synthesize bimodal MWD polymers with both controlled MW and MWD, due to the concurrent presence of conventional free radical polymerization11 in these systems.…”

Producing bimodal molecular weight distribution polymers through facile one‐pot/one‐step RAFT polymerization

“…For example, Lenzi et al3 produced bimodal MWD polymer resins of polystyrene and poly(butyl acrylate) using nitroxide‐mediated polymerization combined with conventional free radical polymerization. Wan et al21 reported formation of bimodal MWD poly(methyl methacrylate) using controlled radical polymerization catalyzed by CuCl/bis(2‐dimethyl‐aminoethyl) ether (BDE) complex in aqueous medium. It must be emphasized, however, that all these strategies mentioned earlier have failed to synthesize bimodal MWD polymers with both controlled MW and MWD at the same time, which has been a great challenging topic until now.…”