Polymerization of Styrene-Butadiene Block Copolymers Using a Dicarbanion Initiator Made by the Reaction of Lithium with .alpha.-Methylstyrene

Hsieh, Henry Chi-Chen; Kao, Hwei-Ling; Cheng, Danling; Tsiang, Raymond Chien‐Chao; Huang, Der-Chi

doi:10.1021/ma00117a005

Cited by 5 publications

(2 citation statements)

References 8 publications

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“…SIS contains four segments: styrene, 1,2-isoprene, 3,4-isoprene, and cis / trans -1,4-isoprene . Containing both aromatic hard chain segment and aliphatic soft chain segment, SBS/SIS is a kind of important thermoplastic elastomer. − SBS/SIS can be used as impact modifier of polyolefin resin, sole material, and adhesive, but its most important application is as modifier of asphalt. However, there are two kinds of unsaturated structures in SBS/SIS: benzene rings and double bonds.…”

Section: Catalytic Hydrogenation Of Unsaturated Polymersmentioning

confidence: 99%

Advances in the Catalytic Hydrogenation and Properties of Unsaturated Polymers

Yan

Cao

2023

Macromolecules

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Polymer reaction and performance improvement are one of the important contents in the field of polymer materials science and engineering, in which polymer catalytic hydrogenation is an important part of polymer reaction. We reviewed the research achievements on polymer hydrogenation over the past 70 years and studied the mechanism of the hydrogenation reaction from the aspects of performance changes before and after polymer hydrogenation, the catalyst preparation/structure−activity relationship, and polymer hydrogenation kinetics. We pointed out the difficulty in separation and unsatisfactory high-temperature adaptability of traditional homogeneous catalysts and first proposed four effects affecting traditional heterogeneous polymer hydrogenation: scale effect, conformation effect, viscosity effect, and adhesion effect. Based on the structure−activity relationship of polymers, we put forward the application direction of hydrogenated polymers at present. We found that using a new kind of nanometal catalyst (Pd/CNTs@FN) as hydrogenation catalyst can effectively reduce or eliminate the negative effects of these four effects on the polymer hydrogenation reaction, and it is easy to separate from the reaction system. The addition of CNTs can effectively increase the specific surface area of the catalyst and strengthen the interaction between reactants and catalyst. Subsequent research should focus on designing the multiscale structure and improving low-temperature activity of the catalyst, reducing process cost, and using green and efficient separation methods to eliminate adverse effects, create a green and efficient polymer reaction system, accelerate the industrialization of polymer hydrogenation process, and provide theoretical guidance for the research and development of new polymer materials.

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Section: Catalytic Hydrogenation Of Unsaturated Polymersmentioning

confidence: 99%

Advances in the Catalytic Hydrogenation and Properties of Unsaturated Polymers

Yan

Cao

2023

Macromolecules

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“…One major difficulty met in the latter case is the limited solubility of dicarbanionic initiators in apolar solvents, media that are required for the preparation of a polybutadiene central block with a high content in 1,4-units and elastomers with optimal properties. Whether obtained by reaction of BuLi with appropriate divinylic species − in 2:1 ratio or by generation of ion radical species which then couple (e-transfer from lithium to α-substituted vinyl monomers), organolithium diinitiators indeed require the presence of active polar additives to efficiently initiate polymerization, which in turn modifies the stereochemistry of the polydiene block and increases its content in 1,2 unsaturations. A dilithiated carbanionic initiator that would be entirely soluble in apolar medium in the absence of any additives or ligands and yet reactive enough is thus very much in demand.…”

mentioning

confidence: 99%

High Performance Poly(styrene-b-diene-b-styrene) Triblock Copolymers from a Hydrocarbon-Soluble and Additive-Free Dicarbanionic Initiator

Matmour

Wadgaonkar

et al. 2006

J. Am. Chem. Soc.

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A new hydrocarbon-soluble (additive-free) dicarbanionic organolithium initiator, obtained by a simple halogen-lithium exchange reaction (Gilman's reaction) from a diarylhalide containing a side C15 alkyl chain, has been designed and used to initiate the anionic polymerization of butadiene and styrene. The dilithiated species formed afford well-defined poly(styrene-b-butadiene-b-styrene) (SBS) triblock copolymers with a high percentage of 1,4-microstructure polybutadiene (91%) and excellent mechanical properties, such as ultimate tensile strength higher than 30 MPa and elongation at a break of 1000%. This represents a breakthrough in the synthesis of SBS polymers, one of the most used thermoplastic elastomers.

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