Copolymerization of 1,3-butadiene with phenyl/phenethyl substituted 1,3-butadienes: a direct strategy to access pendant phenyl functionalized polydienes

Abstract

Copolymerization of 1,3-butadiene with various types of phenyl substituted 1,3-butadiene derivatives, including (E)-1-phenyl-1,3-butadiene (PBD), 1-phenethyl-1,3-butadiene (PEBD), 1-(4-methoxylphenyl)-1,3-butadiene (p-MEPBD), 1-(2-methoxylphenyl)-1,3-butadiene (o-MEPBD) and 1-(4-N,N-dimethylaminophenyl)-1,3-butadiene (p-DMPBD), by using a coordination polymerization system of CpTiCl₃/MAO is reported herein. Comonomers PBD and PEBD can be copolymerized with 1,3-butadiene in a large range of comonomer feed ratios (0–44.6% for PBD, 0–30.2% for PEBD), affording the targeted copolymers with well-controlled comonomer incorporations, molecular weights, polydispersities and microstructure, whereas no corresponding copolymer products were obtained under identical conditions when p-MEPBD, o-MEPBD and p-DMPBD were employed. Moreover, different polymerization parameters, including temperature, Al/Ti ratio, etc., posed a significant influence on the polymerization behaviors, as well as the properties of the resultant copolymers. Microstructure analysis by NMR spectra revealed high 1,4-selectivities of the catalysts, and the glass transition temperature (T_g) of the resulted copolymer was found to be highly dependent on the incorporation content of the comonomers; with an increasing comonomer content, a gradually increasing T_g was demonstrated.