Neodymium 3-isopropoxide/methylaluminoxane/tert-butyl chloride catalyst for 1,3-diene polymerization

摘要

A catalyst composed of neodymium iso-propoxide (Nd) and methylaluminoxane (MAO) was highly effective in isoprene (IP) polymerization in heptane even at a fairly low MAO level ([Al]/[Nd]=30). The produced polymer featured narrow molecular weight distribution (MWD, M_w/M_n = 2.0), while a slightly low cis-1,4 content (ca. 90%). When tert-butyl chloride (Cl) was added as a chlorine source and the ternary catalyst system formed, both polymer yield and cis-1,4 content (94%) significantly improved. The optimum activity achieved at [Cl]/[Nd]=1.0-1.5. The catalyst addition order affected the polymer yield in an order of (Nd + MAO)+Cl > (Nd+Cl)+MAO > (MAO+Cl)+Nd. The ternary catalyst polymerized 1,3-butadiene (BD) in a high yield to afford polymer with fairly narrow MWD (M_w/M_n < 1.60) and high cis-1,4 content ( > 95%). The above catalyst copolymerized 1,3-butadiene and isoprene to form random copolymer with narrow MWD (M_w/M_n < 1.50) and high cis-1,4 contents of both monomer units (BD, 96%; IP, 96%).