Shape Memory Thermoplastic Polyamide Elastomer Based on PA1212

Shape memory polyamide elastomers have attracted large attention owing to a variety of favorable properties (e.g., designable chemical structure, good thermal stability, flexibility, and elasticity, et al). However, the polyamide elastomer reported recently still lack good mechanical property. In the present work, a new type of shape memory thermoplastic polyamide elastomer (TPAE), composed of long carbon chain PA1212 and polytetramethylene ether glycol (PTMEG), is synthesized through two-step melt polycondensation, which is named as poly(ether- b -amide) (PEBA). The chemical structure of PEBA is confirmed by FTIR results and it also shows excellent mechanical properties. PEBA, possessing two melting temperatures, stay in microphase separation among PTMEG soft domains and PA1212 hard domains that are amorphous and α crystal, respectively. Furthermore, PEBA can fix a temporary shape after the heated strip is twisted and cooled down and then recover to the original shape after secondary heating, which is attributed to the fixing force provided by PTMEG domains and entropy elasticity of physically cross-linked PA1212 domains, respectively. Besides, PEBA elastomer can be reshaped between ≈190 and ≈380 °C and it also has shape memory behavior. This new kind of TPAE proposes a new smart material for sensors and soft robotics.