Research On Soft Actuators And Light-Driven Moters Based On Poly (P-Phenylene Benzobisoxazole) Nanofiber Composites

Both the soft actuator and the micromotor are devices that convert various forms of energy into mechanical energy,which can realize controllable deformation and self-propulsion motion respectively,and have good application prospects in many fields.Poly(p-phenylene benzobisoxazole,PBO)fiber is a high-performance polymer fiber material with excellent mechanical properties and thermal stability.In recent years,PBO nanofibers and their composites in the form of films and aerogels have shown their potential in the fields of flame retardant materials and interfacial water evaporation.The construction of soft actuators and light-driven motors based on PBO nanofiber composites is expected to further expand the potential applications of PBO nanofibers and develop new self-propelled motors(such as aerogel-based light-driven motors).In this thesis,(PBONF/rGO)/PVA bilayer film and PBONF/rGO composite aerogel have been constructed by integrating PBONF,reduced graphene oxide(rGO)and poly(vinyl alcohol)(PVA).And use them separately to construct a humidity-and light-responsive bilayer soft actuators and light-driven motor that can be translated and rotated at the gas-liquid interface.By using the vacuum assisted filtration(VAF)method,we have constructed a humidity-and light-responsive soft actuator with a bilayer structure by integrating humidity-sensitive PVA,mechanically strong PBONFs,and rGO with conductive properties and photothermal effect into the(PBONF/rGO)/PVA bilayer film.The(PBONF/rGO)/PVA bilayer film shows the tensile strength and modulus of 29.36 MPa and 0.311 GPa.The average light absorptivity of the(PBONF/rGO)/PVA bilayer film is 72.1%,showing strong ability of light absorption which should favor the photothermal conversion with high efficiency.The(PBONF/rGO)/PVA bilayer soft actuators exhibit reversible,durable,large-variable actuation under the trigger of humidity and light irradiation.The resulting deformation of the soft actuators leads to the change of electrical conductivity.As a demonstration,the bilayer actuators are constructed into a rolling cylinder motors driven by light.The PBONF/rGO composite aerogel was prepared by sol-gel method and supercritical carbon dioxide drying.The average light absorptivity of the PBONF/rGO composite aerogel is 71.03%,showing strong ability of light absorption which should favor the photothermal conversion with high efficiency.The motor constructed based on the aerogel material can perform rapid motion on the gas-liquid interface under illumination,and its motion mechanism is the Marangoni effect.The photothermal effect of PBONF/rGO under illumination causes the local temperature to rise,forming a surface tension gradient around the motor,which in turn pushes the motor for rapid translation or rotation.By injecting dimethyl silicone oil into the aerogel,the hydrophobicity of the material can be improved,thereby reducing the resistance of the motor.The present work has shown that after the adsorption of dimethicone,the translational and rotational speed of the motor increase significantly.In conclusion,this thesis has achieved a new step for the construction of PBONF-based soft actuator and light-driven motor,expands the potential application field of PBO nanofiber,and has achieved the construction of aerogel motor.