Controlled Chain Walking for the Synthesis of Thermoplastic Polyolefin Elastomers: Synthesis, Structure, and Properties

Abstract

Thermoplastic elastomers are attractive materials because of their ability to be melt-processed, reused, and recycled, unlike chemically cross-linked elastomers such as rubber. We report the synthesis and mechanical properties of polyolefin-based thermoplastic elastomer block copolymers. A simple one-pot procedure is employed, using a living arylnaphthyl-α-diimine Ni(II) "sandwich" complex to generate high crystallinity hard blocks from 1-decene and low crystallinity soft blocks from ethylene. Various block structures are accessed, ranging from a diblock up to a heptablock copolymer. Statistical copolymers of 1-decene and ethylene are also synthesized for comparison. All resulting polymers behave as elastomers, with properties that modulate with hard and soft block composition, block architecture, and polymerization solvent. Triblock copolymers demonstrate strain at break values up to 750%, with elastic strain recoveries up to 85%. Interestingly, statistical copolymers demonstrate strain at break values upward of 1120% and elastic strain recoveries up to 77%. Creep experiments were performed to determine the resilience of these materials to deformation. It is found that higher block architectures (triblock and above) have greater resistance to strain-induced deformation than lower block architectures (diblock and statistical).

A continuing legend: the Brookhart-type α-diimine nickel and palladium catalysts

“…In addition, they also reported the synthesis of TPEs from the block copolymerization of 1-decene and ethylene using C21b. 94 Polyolefin-based block copolymers with good crystallinity hard blocks were generated from 1-decene polymerization by high 2,1-insertion. Recently, Brookhart and co-workers have investigated some "sandwich"-type α-diimine palladium catalysts C22 ( Fig.…”

A mechanistic study on the synthesis of branched functional polyethylene through reactive co‐polymer approach

“…Moreover, such developments have opened a new pathway toward production of linear polyethylene‐like structures using liquid olefinic monomers instead of ethylene . Thanks to the diversity of the catalytic structures, tunable polymer architectures from hyperbranched to linear are effectively synthesized using linear α‐olefins monomers . This way, polyethylene can be made in the liquid phase and under environmental pressure, without expensive handling equipment required for handling gaseous ethylene monomer.…”

“…[23,24] Thanks to the diversity of the catalytic structures, tunable polymer architectures from hyperbranched to linear are effectively synthesized using linear α-olefins monomers. [25][26][27][28][29][30][31][32] This way, polyethylene can be made in the liquid phase and under environmental pressure, without expensive handling equipment required for handling gaseous ethylene monomer. Polymerization conditions can be used as levers to control the chain walking mechanism, and consequently the final architecture and properties.…”

Highly resilient polyethylene elastomers prepared using α‐diimine nickel catalyst with highly conjugated backbone

“…The high-molecular-weight hyperbranched polyethylene chains are prone to form physical crosslinks in high density, endowing the material with excellent mechanical and elastomeric recovery properties. [29][30][31][32] Simultaneously, copolymerization of ethylene and some polar-functionalized co-monomers catalyzed by α-diimine palladium and phosphine-sulfonate-palladium catalysts can also generate copolymers with good mechanical properties. [26][27][28] In recent years there have been interesting research works concerning copolymerization of ethylene and α-olefins (1-hexene, 1-octene, 1-decene, 1-dodecene) catalyzed by α-diimine Ni(II) catalyst for the preparation of thermoplastic elastomers.…”

“…[26][27][28] In recent years there have been interesting research works concerning copolymerization of ethylene and α-olefins (1-hexene, 1-octene, 1-decene, 1-dodecene) catalyzed by α-diimine Ni(II) catalyst for the preparation of thermoplastic elastomers. [29][30][31][32] Simultaneously, copolymerization of ethylene and some polar-functionalized co-monomers catalyzed by α-diimine palladium and phosphine-sulfonate-palladium catalysts can also generate copolymers with good mechanical properties. [33,34] Yet, it is more convenient and economical if ethylene can be used as the only monomer to prepare polymers with good mechanical properties.…”