(654h) Preparation and Characterization of Dual-Branching Thermoplastic Polyolefin Elastomer Via a Tandem Solution Copolymerization System

Thermoplastic elastomers (TPEs) are regarded as “the third-generation rubber”, following the first-generation natural rubber and the second-generation synthetic rubber. Among them, thermoplastic polyolefin elastomers (TPE-O) demonstrate good mechanical and electrical insulation properties as well as resistance to chemicals and weathering. As a result, they are extensively applied in the automobile, construction, and electronics fields.

Recently, we developed a novel tandem catalytic system to produce a comb-branched polyolefin thermoplastic elastomer (CPOE), which has crystalline polyethylene as side chains and amorphous ethylene/α-olefin random copolymers as primary chains^[1]. CPOE has a wide usage temperature (high melting temperature (>120 °C) and low glass transition temperature (<−60 °C)) and excellent mechanical properties (the elongation at break reached >1200%). However, the excessive unreacted macromonomers may exert some negative effect on the elastic recovery of CPOE.

In order to further improve CPOE performance, we synthesized a dual long chain branching structure thermoplastic polyolefin elastomer (DPOE), which has a comb-/H-shaped- branched structure. In this polymerization process, we used a tandem catalyst system consisting of a Zr ligated with phenoxycycloalkylimine (FI-Zr) and a constrained geometry catalyst (CGC-Ti). Linear PE macromonomers were first synthesized by the FI-Zr catalyst, then the CGC-Ti catalyst was employed in the copolymerization of ethylene, 1-octene, 1,5-diene, and the PE macromonomers. The obtained DPOEs not only maintained the advantages of CPOE such as high melting temperatures, low glass transition temperatures and high elongations at break, but also surpassed CPOE with significantly higher tensile strength and elastic recovery performance.

REFERENCES

[1] Kailun Zhang, Pingwei Liu, Wen-Jun Wang, Bo-Geng Li, Weifeng Liu, and Shiping Zhu. Macromolecules. 2018, 51, 8790-8799