Anionic Polymerization of Acrylic Monomers. 21. Anionic Sequential Polymerization of 2-Ethylhexyl Acrylate and Methyl Methacrylate

Abstract

A mixed complex of a polydentate lithium alkoxide, i.e., lithium 2-(2-methoxyethoxy) ethoxide (LiOEEM), and of a mono-or bisfunctional organolithium initiator, i.e., (diphenylmethy1)lithium (DPMLi) or lithium naphthalene/diphenylethylene, has been used to synthesize well-controlled AB (BA), ABA, and BAB block copolymers of methyl methacrylate (MMA) (A) and 2-ethylhexyl acrylate (2EtHA) (B), irrespective of the monomer addition order. Although the 2EtHA block copolymerization initiated with monofunctional living PMMA macroanions at -78 "C in a 75/25 toluene/THF mixture gives rise to a precisely-tailored PMMA-b-P2EtHA diblock polymer, the reverse sequence, i.e., from P2EtHA anions to the MMA type monomer, always results in contamination by homo-P2EtHA. This has been interpreted in terms of the short shelf lifetime of P2EtHA anions present. Nevertheless, a pure P2EtHA-b-PMMA type diblock copolymer can be produced at -100 "C, while keeping other conditions unchanged. More importantly, a well-controlled PMMAb-P2EtHA-b-PMMA triblock copolymer has been prepared through a three-stage process with a monofunctional initiator, acutally providing a potential pathway toward the direct synthesis of a novel type of fully acrylic thermoplastic elastomer, instead of the more complicated hydrolysis/transalcoholysis process previously demonstrated by us. IntroductionIt has been recently demonstrated by us that d o dual polydentate lithium alkoxides, such as 242-methoxyethoxy) ethoxide (LiOEEM), can efficiently form a stable and bulky p l a complex with lithium ester enolates in solution' and should consequently be very effective in

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

“…Nevertheless, this improvement is not good enough to allow well controlled (meth)acrylate block copolymers, e.g. poly(MMA)-b-poly(2EHA)-poly(MMA) [19] and poly(MMA)-b-poly(nBA)-b-poly(MMA) [20], to be synthesized. Therefore, the MnBM triblock block copolymers were synthesized indirectly, i.e.…”

Anionic polymerization of methacrylic monomers: characterization of the propagating species

“…initiator, solvent, temperature, it is possible to impart livingness to the polymerization of both acrylate and methacrylate monomers, and thus to implement the engineering of useful (meth)acrylate-based products, e.g. polyacrylates, polyacrylic acid [30], mono-disperse random copolymers of predictable molecular weights and low polydispersities [53,55,56], diblock copolymers with styrene and dienes having potential interfacial activity, triblock and star-shaped diblock copolymers with characteristics of thermoplastic elastomers [57,58], macromonomers [59,60], telechelics [8] and halatotelechelic polymers with mesomorphic phase organization [61].…”

The Organometallic Polymerization of (Meth)acrylates: An Overview

“…Large "metal free" organic counterions, including tetraalkylammoniums (68-70), tetraphenylphosphonium, and T4V (71) have also been employed to control polymerization at J p 4 + LiOEEM higher temperatures (0-20 °C) with reasonable success. Lithium 2-(2-methoxyethoxy) ethoxide (LiOEEM), which incorporates both cation-complexing and endgroupbridging moieties, has recently been used as an additive to prepare monodisperse poly(n-butyl acrylate) (PDI = 1.15) and poly(2-ethylhexyl acrylate) (PDI = 1.07) and related block copolymers (72)(73)(74). Unfortunately, the presence of chain transfer prevents the synthesis of similarly well-defined polyacrylates with shorter primary ester chains.…”