4D printing high temperature shape-memory poly(ether–ether–ketone)

Abstract Shape-memory polymers have exhibited extensive attractive properties for practical utility and applied potential, such as in clothing industry and for medical implants, which demands soft materials amenable to change shapes at low temperature. Whereas, potential applications in aerospace engineering require materials with higher modulus and higher transition temperature to ensure their effectiveness under harsh environments. As an engineering thermoplastic polymer material, poly(ether–ether–ketone) (PEEK) is a promising candidate that meets the stringent requirements for aerospace applications. Yet, additive manufacturing of PEEK polymers, to bring out the full potential of the materials, remains challenging and unfulfilled because of the intrinsic very high processing temperature and high modulus. In this paper, we present that 4D printing of the high temperature PEEK polymer with outstanding shape memory properties. We systematically investigate the effect of different printing parameters and heat treatment conditions on the corresponding shape memory performance, which has been rarely reported. The highest shape fixity ratio and highest shape recovery ratio that we can achieve in the 3D-printed PEEK samples is 99% and 87.8%, respectively, with Young’s modulus of 3.23 GPa and good thermal stability below 520 °C. Furthermore, the incomplete shape recovery processes have been exploited to fabricate more complex programming of shape changes and to demonstrate the potential for practical applications, and models of PEEK have been designed and printed to demonstrate the outstanding shape memory properties and for potential applications in high temperature environment.