Anionic polymerization of primary acrylates as promoted by lithium 2‐(2‐methoxyethoxy) ethoxide

Abstract

SYNOPSISSome 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 p-u dual ligand, i.e., a polydentate lithium alkoxide, at low temperature. It has been found that lithium 2-(2methoxyethoxy) 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. C 1997 John Wiley & Sons, Inc. Keywords: anionic polymerization q primary acrylates q n-butyl acrylate q n-nonyl acrylate q polydendate lithium alkoxides

Synthesis of poly(methyl methacrylate)-b-poly(n-butyl acrylate)-b-poly(methyl methacrylate) triblocks and their potential as thermoplastic elastomers

“…This situation is however improved by the addition of chelating µ-σ dual ligand, such as polydentate lithium alkoxide particularly in case of 2-ethylhexyl acrylate [17] and n-butyl acrylate [18]. Nevertheless, this improvement is not good enough to allow well controlled (meth)acrylate block copolymers, e.g.…”

Anionic polymerization of methacrylic monomers: characterization of the propagating species

“…Under these specific conditions, the homo and block copolymerization of methacrylates has fallen under control [34,35]. This improvement over classical anionic methods has however no beneficial effect on acrylate polymerizations [36] and rapidly looses efficiency when methacrylates are polymerized in non-polar solvents [37] or at relatively high temperatures. Among attempts to improve this situation, the use of ligands interacting with active metal containing initiating and propagating ion pairs was most positive, so that "ligated anionic polymerization" raised optimistic prospects.…”

Anionic polymerization of acrylates. XIV. Synthesis of MMA/acrylate block copolymers initiated with ester-enolate/tert-alkoxide complex

“…1, trace 2), is slightly higher than that of the PMMA homopolymer (M w / M n Z1. 16). Nevertheless, the eluogram shows bimodal MWD of the copolymerization product containing a lowmolecular-weight part having a retention time comparable with that of the PMMA precursor.…”

“…Here, the found polydispersity indexes were ca. 1.05-1.1 for EtHA [51], 1.10-1.30 for BuA [16], 1.30-1.55 for EtA and 1.50-1.60 for methyl acrylate polymerizations in toluene/THF mixture at K78 8C. Also poly(MMA-b-BuA) copolymers, prepared with the same system, exhibit slightly broader MWD than poly(MMA-b-nonyl acrylate) [37] probably as a consequence of a favorable effect of the longer nonyl group.…”

“…Later on, the spectrum of utilizable ligands was extended by LiCl [13,14], bidentate lithium alkoxides (e.g. Li 2-(2-methoxyethoxy)ethoxide, MEEOLi) [15][16][17], alkylaluminiums [18][19][20][21], Li perchlorate [22], Li silanolates [23], etc. Such ligands form with the initiator used and/or with growing chain-ends cross-complexes of various compositions, modifying thus the immediate environment of the living macroanion.…”