Shape Memory Behaviour of PMMA-Coated NiTi Alloy under Thermal Cycle

Both poly(methyl methacrylate) (PMMA) and NiTi possess shape memory and biocompatibility behavior. The macroscale properties of PMMA-NiTi composites depend immensely on the quality of the interaction between two components. NiTi shape memory alloy (SMA) and superelastic (SE) sheets were spin coated on one side with PMMA. The composite was prepared by the spin coating method with an alloy-to-polymer-thickness ratio of 1:3. The bending stiffness and radius of curvature were calculated by using numerical and experimental methods during thermal cycles. The experimental radius curvatures in actuation have good agreement with the model. The change in shape results from the difference in coefficients of thermal expansion between PMMA and NiTi. Actuation temperatures were between 0 and 100 degrees C for the SMA-PMMA composite with a change in curvature from 10 to 120 mm with fixed Young's modulus of PMMA at 3 GPa, and a change in Young's modulus of NiTi from 30 to 70 GPa. PMMA-NiTi composites are useful as actuators and sensor elements.

Automated summary

Both PMMA and NiTi possess shape memory and biocompatibility behavior. The study focuses on the preparation of PMMA-NiTi composites and the investigation of their properties. The experimental results agree well with the model, and the change in shape is attributed to the difference in coefficients of thermal expansion between PMMA and NiTi. The composite has potential applications as actuators and sensor elements.