Additive-Promoted Grignard Reagent Mediated Polymerization With Increased Radical Characteristic Yielding Polystyrene With Narrow Molecular Weight Distribution

Abstract

Gaining polymer with narrow molecular weight distribution (Đ) by efficient living polymerization methods is fundamental and essential in polymer science. Grignard reagent mediated anionic polymerization is capable of low Đ, however, is not suitable for the polymerization of nonpolar monomers like styrene (St). Here, several kinds of additives like lithium chloride (LiCl) and N,N,N′,N′′,N′′-Pentamethyldiethylenetriamine (PMDETA) are demonstrated as efficient additives that can promote Grignard reagent mediated polymerization of St. Through LiCl-promoted Grignard reagent mediated polymerization, polystyrene (PS) with manipulated low Đ is successfully achieved under mild conditions with full monomer conversion, by using a series of Grignard reagents (RMgX) in the presence of LiCl. In comparison, no PS can be prepared for Grignard reagents in the absence of additive. Electron paramagnetic resonance reveals that radical characteristic of Grignard reagent is increased in the presence of additive, which eventually enables the successful polymerization of St under mild conditions with full monomer conversion. This work therefore opens a simple additive strategy to promote current living polymerization method and expands the monomer library of Grignard reagent mediated living polymerization, which might cause inspirations to current living polymerization and polymer chemistry.