Polyurethanes Reinforced with Polyethylene Nanocrystals: Synthesis, Triple Shape Memory, and Reprocessing Properties

In this contribution, we reported a new approach to reinforce polyurethane (PU) networks with polyethylene (PE) nanocrystals. The PU-PE networks were synthesized via the co-cross-linking of alpha,omega-dihydroxyl-terminated PU telechelics with alpha,omega-dihydroxyl-terminated PE telechelics, which involved the use of 3-isocyanatopropyltriethoxysilane. In the networks, notably, the PE nanocrystals were generated via a crystallization-driven self-assembly approach. The reinforcement of PE nanocrystals on the PU networks was evidenced by the significant improvement in thermal and mechanical properties. Thanks to the generation of networks, the PU-PE networks displayed shape memory properties. Furthermore, the networks displayed triple shape memory properties with the introduction of PE nanocrystals. In addition, the PU-PE networks possessed the reprocessing properties through silyl ether metathesis, while zinc trifluoromethanesulfonate [Zn(OTf)(2)], a Lewis acid, was introduced and used as a catalyst. The reprocessing properties can be utilized further to reprogram the original shapes of the shape memory polymers.

Automated summary

This contribution presents a novel approach to reinforce polyurethane networks with polyethylene nanocrystals. The networks were synthesized through the co-cross-linking of PU and PE telechelics, with PE nanocrystals generated via a crystallization-driven self-assembly method. The introduction of PE nanocrystals significantly improved the thermal and mechanical properties of the networks, and also enabled shape memory capabilities. Additionally, the networks possessed reprocessing properties with the use of zinc trifluoromethanesulfonate as a catalyst.