Polymerization kinetics of ethylene oxide methacrylates in ionic media

The radical polymerization of ethylene oxide (PEGylated) methacrylates in ionic media has been studied. Lithium salts interact with the monomer causing a significant increase in the propagation rate constant, k_p, and also providing an ionic and highly viscous medium that sharply decreases the termination rate coefficient, k_t. Both features make the polymerization reactions with lithium salts faster compared to the bulk monomer. The systems are studied by means of FT-IR spectroscopy to identify the interactions between the monomer and the lithium salt. In addition, an extensive kinetic study by PLP-SEC has been performed to study the influence of the lithium salt on k_p and k_t in the polymerization of these monomers. These results are compared to those obtained when ionic liquids are used as polymerization medium. A polymerization system in which k_p is enhanced and k_t is considerably decreased is presented. The system is based on the use of ionic salts bearing lithium cations. FT-IR studies demonstrate that Li⁺ cations interact with the monomer molecules. The association ratio (α) to the carbonyl group is responsible for the observed increase in the propagation rate constants, k_p, which have been determined by PLP experiments under different reaction conditions.