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

摘要

Copolymerization of binary mixtures of alkyl (meth) acrtylates has been initiated in toluene by a mixed complex of lithium silanolate (s-BuMe_2SiOLi)-and s-BuLi (molar ratio > 21) formed in situ by reaction of s-BuLi with hexamethylcyclotrisiloxane (D3). Fully acrylate and methacrylate copolymers, i.e., poly(mehtyl 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 methacrylate-co-n-butyl methacrylate), poly (isobornyl methacrylate-co-n-butyl methacrylate) of a rather narrow molecular weight distribution have been synthesized. However, copolymerization of alkyl acrylate and methyl methacrylate pairs has completely failed, leading to the selective formation of homopoly (acrylate). As result of the isotactic stereoregulation of the alkyl methacylate polymerization by the s-BuLi/s-BuSiOLi intitator, highly isotactic random and block copolymers of (alkyl) methacrylates have been prepared and their thermal behavior analyzed. The strtucture of isotactic poly (ethyl methacrylate-co-methyl methacrylate) copolymers ahs been analyzed in more detail by Nuclear Magnetic Resonance (NMR).