New initiator system for the anionic polymerization of (meth)acrylates in toluene. IV. Random copolymerization of (meth)acrylates in toluene initiated by s-BuLi ligated by lithium silanolates

Copolymerization of binary mixtures of alkyl (meth)acrylates has been initi ated in toluene by a mixed complex of lithium silanolate -(s . BuMe2SiOLi)- and s-BuLi (molar ratio > 21) formed in situ by reaction of s-BuLi with he xamethylcyclotrisiloxane (D-3). Fully acrylate and methacrylate copolymers, i.e., poly(methyl acrylate-co-n-butyl acrylate), poly(methyl methacrylate- co-ethyl methacrylate), poly(methyl-methacrylate-co-n-butyl methacrylate), poly(methyl methacrylate-co-n-butyl methacrylate), poly(isobornyl methacryl ate-co-n-butyl methacrylate), poly(isobornyl methacrylate-co-n-butyl methac rylate) of a rather narrow molecular weight distribution have been synthesi zed. However, copolymerization of alkyl acrylate and methyl methacrylate pa irs has completely failed, leading to the selective formation of homopoly(a crylate). As result of the isotactic stereoregulation of the alkyl methacry late polymerization by the s-BuLi/s-BuMe2SiOLi initiator, highly isotactic random and block copolymers of(alkyl) methacrylates have been prepared and their thermal behavior analyzed. The structure of isotactic poly(ethyl meth acrylate-co-methyl methacrylate) copolymers has been analyzed in more detai l by Nuclear Magnetic Resonance (NMR). (C) 1999 John Wiley & Sons, Inc.