η³‐π‐Allyl Acetoxyl Ni Complex, an Efficient Initiator for Synthesis of Hydroxyl‐Terminated Polybutadiene with High cis‐1,4 Unit Content

Abstract

A novel Ni‐based initiator is designed and synthesized for obtaining a hydroxyl‐terminated polybutadiene (HTPB) with higher cis‐1,4 unit content (≥90%). By investigating the effect of the butadiene skeleton structure and counterion on initiating efficiency, it is found that [η3‐Ni(CH2CHCHCH2OOCH3)][BPhF 4] complex is a feasible combination to be used as an initiator. 1H‐NMR data prove that the initiator structure obtained is in accordance with the original design. The result of 1H‐NMR, 13C‐NMR, FT‐IR confirms that HTPB synthesized not only gains a significant amount in cis‐1,4 unit content (≥90%) compared with the HTPBs by free radical and anionic polymerizations, but also its molecular weight and molecular weight distribution can be effectively controlled during synthesis process. Because of the much higher cis‐1,4 unit content, the glass‐transition temperature of HTPB obtained via [η3‐Ni(CH2CHCHCH2OOCH3)][BPhF 4] is markedly reduced; as a result, its low‐temperature mechanical property can also be significantly improved.

Synthesis of butadiene/isoprene–styrene di-block copolymer with high cis-1,4 unit content based on a neodymium phosphate ester

“…The peak at 750 cm À1 , 967 cm À1 and 911 cm À1 represent of cis-1,4, trans-1,4 and 1,2-unit in the PB segment and the data revealed that the diblock copolymer has very high cis-1,4 PB unit content (cis-1,4 >98%). 23,26 In the Fig. 4, the chemical shis at 27.5 ppm, 32.6 ppm, 34.2 ppm and 145.2 ppm represent the cis-1,4, trans-1,4 and 1,2-PB segment and PS segment, respectively.…”

A New Strategy for the Synthesis of Hydroxyl Terminated Polystyrene-b-Polybutadiene-b-Polystyrene Triblock Copolymer with High Cis-1, 4 Content

“…The synthesis of [η 3 -Ni(CH 2 CHCHCH 2 OOCH 3 )][BPh F 4 ] is shown in Scheme 2. Details on the characterization of [η 3 -Ni(CH 2 CHCHCH 2 OOCH 3 )][BPh F 4 ] are found in the references [29].…”

“…(iii) Transition metal-based catalysts should be used to ensure a high cis-1,4 content. Our previous work reported a new type of allyl nickel catalyst, [η 3 -Ni(CH 2 CHCHCH 2 OOCH 3 )][BPh F 4 ] [29], which meets all three criteria. Thereby, this catalyst fits the current needs in that (a) there are protected hydroxyl groups on the catalyst surface, (b) [η 3 -Ni(CH 2 CHCHCH 2 OOCH 3 )][BPh F 4 ] it can initiate styrene and butadiene polymerization without a cocatalyst, and (c) nickel, which exhibits strong coordination to olefin monomers, is the center of the catalyst to ensure the high cis-1,4 content of the polybutadiene sections.…”

A novel synthetic strategy for styrene–butadiene–styrene tri-block copolymer with high cis -1,4 units via changing catalytic active centres

“…−80°C), indicating high performance at low temperatures. The copolymer with higher cis -1,4 unit content inherently possesses a much lower molecular internal rotation energy and stronger intermolecular force, which could maintain a better flexibility at an extremely low temperature [18,33].

Figure 6.DSC curves of SBS via changing catalytic active centres (entry 3, in table 1, X st = 35.1 mol%).

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