Preparation Of Patterned PVDF Surface Via Hot-pressing And Its Properties

Smart actuators that can generate programmable deformation under environmental stimuli(such as light,electricity,heat,magnetic field,humidity,organic solvent,etc.)have great application potential in soft robots,sensors,bionic devices,artificial muscles and other emerging fields.In addition,some actuators with sensing properties can realize real-time feedback of the motion state in the process of actuating deformation,which is beneficial for us to monitor and control its actuating process more accurately and effectively.Unfortunately,there are still many problems in the reported actuators,such as complex preparation process,excessive use of organic solvent,high cost,interface failure,single deformation form and difficulty in combining actuating and sensing performances,which greatly limit their wide application.Therefore,it remains a great challenge to develop a simple,environmentally friendly,and economical method to fabricate actuators with excellent performance,programmable deformation,and both actuation and sensing performances.In this paper,based on a stainless template with microgrooved arrays,a PVDF patterned film actuator was successfully fabricated by vacuum-assisted hot-press molding.In addition,a SWCNTs/PVDF composite film actuator with both actuating deformation and piezoelectric sensing performances was further prepared by constructing the SWCNTs conductive network on the PVDF patterned film by spraying method.The main results of the research are as follows:1.Fabrication and actuating performance of PVDF patterned film.In this paper,the PVDF patterned film actuator with micro-ridge arrays was fabricated by vacuum-assisted hot-press molding.Then,the effects of hot-pressing parameters on the microstructure,orientation,crystal form,and crystallinity of PVDF films were systematically studied.With the increase of hot-press temperature and time,the height difference between the front and back of PVDF films increased first and then decreased.However,the molecular chain orientation,relative content of α-phase andβ-phase crystals,and crystallinity of PVDF films prepared under different hot-press parameters are basically the same,which indicates that the above factors will not cause differences in the actuating behavior of the films.Subsequently,the actuating behaviors of the PVDF patterned film were systematically studied.It is found that the actuating performance improved with the increase of the micro-ridge height difference.In addition,the PVDF patterned film can not only realize the controllable deformation of direction,curvature and pitch,but also complete the bionic actions such as winding,jumping and weight lifting,showing its application potential in soft robots,sensors,bionic devices,artificial muscles and other fields.2.Fabrication and actuating sensing performance of SWCNTs/PVDF composite film.Based on the PVDF patterned film prepared by vacuum-assisted hot-press molding,the SWCNTs/PVDF composite film actuator integrating actuation and sensing was further fabricated by spraying method.With the increase of spraying times,the mass fraction of SWCNTs in the SWCNTs/PVDF composite film gradually increased,and the surface SWCNTs network gradually improved.Therefore,the surface resistance decreased obviously and then remained basically stable with the increase of spraying times.In addition,the stable interfacial bonding between SWCNTs and PVDF was verified by SEM,FTIR,DSC,and finger rubbing experiment.Finally,the factors affecting the actuating performance and the piezoelectric sensing performance are systematically investigated.It was found that the actuating performance of SWCNTs/PVDF composite film decreased with the increase of spraying times.In addition,the SWCNTs/PVDF composite film can produce a stable output voltage in the process of actuating deformation,and the output voltage increases with the increase of film size and acetone concentration.Obviously,this kind of actuator with actuated sensing performance can feedback the motion state in real time,which will further expand its applications in soft robots,sensors,bionic devices,artificial muscles,etc.