Effect of tert‐Butyl Chloride on the Isoprene Polymerization with Neodymium Isopropoxide/Diisobutylaluminum Hydride and Neodymium Isopropoxide/Methylaluminoxane Catalysts

Abstract

The effect of tert‐butyl chloride (tBuCl) as a third catalyst component on the isoprene polymerization with neodymium isopropoxide (Nd(OiPr)3)/diisobutylaluminum hydride (Al(iBu)2H) and Nd(OiPr)3/methylaluminoxane(MAO) catalysts was examined in heptane at a fixed [Al]/[Nd] ratio of 30 and reaction temperatures of 30 and 60 °C. The Nd(OiPr)3/Al(iBu)2H catalyst was inactive without tBuCl, i.e., at [Cl]/[Nd] = 0, while it showed the highest activity under the conditions of [Cl]/[Nd] = 3.0 and an addition order of {Al(iBu)2H + tBuCl} + Nd(OiPr)3 to yield polyisoprene with relatively low molecular weight (Mn ca. 5 × 104), broad MWD (Mw/Mn ca. 5.4), and high cis‐1,4 content (ca. 96%) at 30 °C. On the other hand, the Nd(OiPr)3/MAO catalyst was effective at [Cl]/[Nd] = 0, and the most active at [Cl]/[Nd] = 1.0–1.5 with an addition order of {Nd(OiPr)3 + MAO} + tBuCl to afford polymer with high molecular weight (Mn ca. 8 × 105), fairly narrow MWD (Mw/Mn ca. 1.6) and high cis‐1,4 content (ca. 94%) at 30 °C. Thus, the novel Nd(OiPr)3/MAO/tBuCl system features high activity, high molecular weight, narrow MWD, and high cis‐1,4 stereospecificity, as compared with the conventional Nd(OiPr)3/Al(iBu)2H/tBuCl system. Effect of the [Cl]/[Nd] mole ratio on the cis‐1,4 contents with Nd(OiPr)3/Al(iBu)2H/tBuCl catalyst. Curve a: at 30 °C, 180 min; curve b: at 60 °C, 90 min.magnified imageEffect of the [Cl]/[Nd] mole ratio on the cis‐1,4 contents with Nd(OiPr)3/Al(iBu)2H/tBuCl catalyst. Curve a: at 30 °C, 180 min; curve b: at 60 °C, 90 min.

Analysis of solution polybutadiene polymerizations performed with a neodymium catalyst

“…These catalysts allow for production of polymer materials with excellent properties with high yields, which are suitable for use as tires and elastic materials [1, 2]. However, the molecular weight distributions (MWDs) of the resulting polymers are not controlled well because of the presence of multiple active sites and the heterogeneity of the catalyst system [1–10]. In addition, cocatalysts are believed to exert a significant effect on the shape of the final MWD of obtained polymer materials [1–9].…”

“…In the past years, distinct catalyst systems (Ni [11, 12], Co [13, 14], Nd [1–10, 15–17], Ti [18, 19], and Sm [20–22]) have been developed for 1,3‐diene polymerizations using methylaluminoxane (MAO) [2–4], borate [16], and alkylaluminum/halides [1–10] as cocatalysts. Titanocene/MAO [18–19] and samarocene/AlR 3 /borane [20–22] catalysts present single‐active catalyst sites and are able to produce high cis ‐1,4 polybutadienes (PB) with the simultaneous control of the MWD and stereoregularity of the obtained polymer material; however, these catalysts require large amounts of MAO to scavenge impurities and activate the catalyst.…”

Efeito do envelhecimento de catalisadores Ziegler-Natta à base de neodímio sobre a polimerização de 2-metil, 1,3-butadieno

“…Os filmes das amostras foram obtidos por vazamento de soluções de polímero em clorofórmio (2%) em célula de KBr. A proporção de unidades 1,4-cis e 3,4 foram determinadas por meio das bandas de absorção em 836 e 890 cm -1 , de acordo com as equações 1, 2 e 3, conforme descrito na literatura [19] .…”

Estudo da polimerização do 2-metil, 1,3-butadieno via catalisadores lantanídicos: influência do tipo de alquilalumínio, da temperatura reacional e da concentração do catalisador

“…Os filmes das amostras foram obtidos por vazamento de soluções de polímero em clorofórmio (2%) em célula de KBr. A proporção de unidades 1,4-cis e 3,4 foi determinada por meio das bandas de absorção em 836 e 890 cm -1 , de acordo com as Equações 1, 2 e 3 descritas na literatura [9] .…”