Tunable shape memory effect and omnidirectional shape change of polyetheretherketone
2022
Ren, Lei | Wang, Zhenguo | Ren, Luquan | Liu, Qingping | Wu, Wenzheng | Song, Zhengyi | Li, Bingqian | Wu, Qian | Zhou, Xueli
The low phase transition and thermal decomposition temperatures of conventional thermoplastics limit the use of shape memory polymers (SMPs) in high-temperature frontier applications. Here, we demonstrate a polyetheretherketone (PEEK) with a high phase transition temperature, high decomposition temperature, and a broad reversible phase transition, where the broad reversible phase transition confers positive double and triple shape memory effects on the PEEK, all of which are highly tunable without changing the material composition. First, the adjustable shape memory properties and reversible deformation behavior of PEEK were identified with dynamic mechanical analysis. Secondly, a pre-strain is designed as a “hinge” in a strip of the PEEK material, and a temperature gradient is introduced into the “hinge” by asymmetric heating to induce bending and folding of the sample toward the heat source. Finally, we further demonstrate the intelligent shape memory properties of PEEK materials, such as sequence unfolding structures using the multiple shape memory effect and a thermotropic-moving sunflower by locally exerting of thermal excitation. This use of the polymer’s own wide range of phase changes and external stimuli to impart programmable deformation properties to the material could open up new avenues for the application of SMPs.
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