Anionic polymerization of primary acrylates as promoted by Lithium 2-(2-Methoxyethoxy) ethoxide

Abstract

Some primary acrylates, such as methyl, ethyl, n-butyl, and n-nonyl acrylate (MA, EA, nBuA and nNonA, respectively) have been anionically polymerized by using diphenylmethyl lithium (DPMLi) as an initiator, in the presence of a chelating - dual ligand, i.e., a polydentate lithium alkoxide, at low temperature. It has been found that lithium 2-(2-methoxyethoxy) ethoxide (LiOEEM) is a very efficient ligand in preventing the anionic polymerization of these monomers from being disturbed by significant secondary transfer and termination reactions. Even for the difficult cases of ethyl and methylacrylate, that approach provides high polymerization yields and low polydispersity, allowing the molecular weight to be predetermined. LiOEEM/initiator molar ratio, solvent polarity, temperature and monomer concentration have proved to be key parameters in the control of the polymerization process. The efficiency of that control is however dependent on the monomer structure and improves with the length of the n-alkyl substituent, i.e., MA < EA < nBuA < nNonA