Gas-phase polymerization of 1,3-butadiene with supported half-sandwich-titanium-complexes

Abstract

Using half‐sandwich‐titanium‐complexes polybutadiene (BR) can be produced with a particular microstructure of about 81% cis, 18% 1,2, and 1% trans units. A stirred bed reactor and a fluidized bed reactor were constructed for gas‐phase polymerization of 1,3‐butadiene by cyclopentadienyltrichlorotitanium (CpTiCl3) on MAO (methylaluminoxane) impregnated silica (MAO/SiO2). The major determinant of polymerization activity and molecular weight is the AlMAO/Ti‐ratio on the carrier. Polymerization activity increases to 14 500 kg BR/(mol Ti*h) with a molecular weight of 1.9×106 g/mol and the catalyst becomes noticeably more stable. Activity further increases when the CpTiCl3 catalyst is prealkylated with small quantities of TIBA (triisobutylaluminium). Systematic methodological experimentation of the heterogenization suggests that a Ti(III)‐species is responsible for polymerization. The gas‐phase polymerization of 1,3‐butadiene reveals a rate of polymerization which is considerably greater than the equivalent rate in the homogeneous system. The polymers all have similar characteristics, pointing to the same active species. The microstructure of the polybutadiene produced was investigated by spectroscopic measurements and by hydration; a preference to block structures of 1,2‐units could not be established.

Stereospecific Polymerizations of Conjugated Dienes by Single Site Iron Complexes Having Chelating N,N,N-Donor Ligands

“…There has been recent interest in the use of soluble transition metal catalysts such as CpTiCl 3 /MAO, − CpTiCl 2 /MAO, CpTiCl 3 /Ph 3 CB(C 6 F 5 ) 4 /AliBu 3 , Ti(OiPr) 4 /MAO, Ti(CH 2 Ph) 4 /MAO, Ni(acac) 2 /MAO, Co(acac) 2 /MAO, and Ni(oct) 2 /AlF 3 /AlEt 3 for 1,4-polymerizations of isoprene and 1,3-butadiene to obtain high molecular weight polymers with low polydispersities as efficient low-cost materials for improved synthetic rubber. 1,2-Poly(1,3-butadiene) and 3,4-poly(isoprene) have also been prepared using homogeneous catalysts like V(acac) 3 /AlEt 3 and Cr(acac) 3 /MAO to use as plastic rollers for printing of polymer films, seals, and children's toys.…”

Additive Effect of Triphenylphosphine on the Living Polymerization of 1,3‐Butadiene with a Cobalt Dichloride‐Methylaluminoxane Catalytic System

“…Simultaneous control of microtacticity and molecular weight of the polymer chain is an interesting topic, but a difficult task in the polymerization of 1,3‐butadiene. Although a number of catalytic systems have been reported to conduct stereospecific polymerization of 1,3‐butadiene for cis ‐1,4,1–11 trans ‐1,4,12,13 syndiotactic‐1,2,14–16 atactic‐1,2,17 and isotactic‐1,2,18 polymers, only limited examples are reported for both stereospecific and living polymerization in 1,3‐butadiene 1–4. In transition metal‐catalyzed polymerization, the addition of a Lewis base is sometimes very effective in the control of the activity, the stereospecificity, and the livingness of the system.…”

Novel neodymium (III) isopropoxide‐methylaluminoxane catalyst for isoprene polymerization

“…Metallocene catalysts activated by methylaluminoxane (MAO) give homogeneous systems, leading to extensive control of the M w / M n and steric structure of polymers in the polymerization of ethylene, α‐olefins, and styrene. Triggered by those remarkable results, a variety of catalysts composed of transition‐metal (e.g., Ti,8–14 V,12, 15–17 Cr,18, 19 Co,12, 20–22 Ni,23–28 Nd,7, 12, 29–34 and Sm35, 36) compounds and MAO were examined in 1,3‐diene polymerization. In the polymerization of 1,3‐butadiene, the use of MAO in place of AlR 3 as a cocatalyst generally affects both the catalytic activity and stereospecificity of the transition‐metal catalysts.…”