Water-responsive actuators based on the solution casted PVA/epoxidized-SBS two-way shape memory bilayer composite film

Water-responsive actuators have been of increasing interest in various applications. In this work, water-responsive actuators based on the bilayer composite film were prepared using commercialized PVA and SBS by a two-step solution casting method. In order to improve the adhesion between the PVA layer and SBS layer, SBS was firstly epoxidized to improve the polarity. Immediately after a thin film was formed on the surface of the epoxidized-SBS (E-SBS)/tetrahydrofuran solution, the PVA aqueous solution was poured onto the film and dried. It was found that the adhesive property between the two layers was improved and the adhesion strength reached 1005 kPa. The resultant bilayer film displayed the water-responsive two-way shape memory effect and exhibited excellent cyclic performance in five cycles. Flower-like and claw-like actuators based on the bilayer composite film were prepared and the actuation performance was demonstrated, suggesting their potential for applications in the fields of biomedicine and sensors.