High performance and multifunctional Janus bio-nanocomposite film for underwater actuators with excellent sensitivity and controllability

Stimuli-responsive materials have been increasingly explored to construct actuators and develop soft robots. Herein, one strategy via regulating lignin-containing cellulose nanofibrils (LCNF) distribution in PVA network followed by alkaline treatment (AT) and pre-stretching to fabricate bio-nanocomposite derived Janus films with stimulus response is proposed. LCNF/PVA-AT film displays obvious asymmetric structure, good mechanical properties, and water-resistance. Based on Janus structure and Hofmeister effect of PVA in salt solution, the applied pre-stretching treatment further enables the as-prepared LCNF/PVA-AT film with an excellently smart and controllable responsiveness to salt solutions. In addition, by adjusting some factors including length–width ratio of the film, salt type and concentration, the deformation degree and response/recovery time of LCNF/PVA-AT film and its based actuators can be controllably designed. The study will enrich the development of green, sustainable and biodegradable polymers derived Janus films, and expand their wide potential applications in multifunctional actuators.