Dual‐Stimuli Shape Memory Thermoplastic Polyurethane/Poly (ε‐Caprolactone) Polymer Composites With Polydopamine‐Coated Halloysite Nanotubes for Enhanced Photo‐Responsive Actuation

ABSTRACT To date, shape memory polymer composites (SMPCs) have made significant progress in terms of material design, driving methods, and application fields. Despite these exciting achievements, the performance of most previous SMPCs remains suboptimal for realizing their full potential in stimuli‐responsive actuators due to their limited single‐stimulus responsiveness and restricted controlling capability. Herein, we report novel dual‐stimuli responsive SMPCs fabricated by embedding PDA@HNTs into a thermoplastic polyurethane (TPU) and poly (ε‐caprolactone) (PCL) blend. The incorporation of PDA@HNTs can not only endow TPU/PCL blends with photo‐thermal conversion capability, but also enhance thermally induced shape memory performance of SMPCs. Specifically, TPU50/PCL50‐PDA@HNTs‐2.0 blend exhibits superior dual shape memory property as manifested by shape fixing ratio of 99.3% and shape recovery ratio of 96.8% in water bath at 65°C, which takes only 10s for recovering permanent shape. Besides, under 808 nm NIR irradiation, the shape fixity ratio and shape recovery ratio of TPU50/PCL50‐PDA@HNTs‐2.0 blend can even reach 99.3% and 99.7%, respectively. More interestingly, we design a laminated‐structure composite to achieve tunable shape recovery time, which allows SMPCs to be customizable in different situations. This work may offer insights into the development of multiresponsive SMPCs, which expands the potential application of shape memory polymers.