Preparation And Performance Study Of PVDF Blended Composite Film And Its Application Insensor

With the continuous progress of technology,flexible electronic devices have been widely used in many fields.Compared with traditional rigid electronics,flexible electronics have better adaptability and malleability and can be adapted in a variety of different environments.In this paper,flexible piezoelectric nanofiber films were prepared by polymer blending and doping with fillers using electrostatic spinning process and applied in flexible electronic devices.The polyvinylidene fluoride（PVDF）blended fiber film prepared by electrostatic spinning technology has high sensitivity and can quickly and accurately detect small pressure changes,thus it is widely used in piezoelectric sensors to realize the conversion of mechanical energy and electrical signals,which opens a new way for the preparation and application of piezoelectric sensors and has broad application prospects.In this paper,the effects on the morphology,structure,mechanical properties,ferroelectric properties,sensitivity and electrical output properties of PVDF blended fibers are investigated.In general,the multifunctional piezoelectric composite films prepared by the method of solution blending and adding different fillers have the advantages of simple preparation,adjustable performance and wide application range.It is a potential new functional material.（1）In the（poly-L-lactic acid（PLLA））system,piezoelectric composite fiber films with both yellow-green fluorescence were prepared by blending PVDF and PLLA and doping with fluorescent complexes（Tb（TTA）₃（TPPO）₂）,which can be applied in flexible piezoelectric sensors.The experimental results showed that with the addition of PLLA and fluorescent complexes theβ-phase content in PVDF increased from 88.5%to 95%,and the crystallinity of the composite fibers was substantially improved.In addition,the sensitivity of the sensor prepared by the composite nanofiber is as high as 0.42 k Pa^-1 under the fine pressure of 0-1k Pa,and the voltage output of the sensor is as high as 2.5 V,which is much higher than that of the pure PVDF fiber film.It provides a new idea for the field of optoelectronic devices and electronic skin.（2）In the polyacrylonitrile（PAN）system,the addition of PAN and conductive filler MWCNTs-COOH further improved the comprehensive performance of PVDF composite fibers.Theβ-phase content of the composite fiber films was as high as 96.8%,and the elongation at break and tensile strength were 180%and 1.5 MPa,respectively,which were higher than those of the PLLA system.Therefore,this composite material has potential applications in fields such as flexible pressure sensors.（3）For the poly（methyl methacrylate）（PMMA）system,the addition of PMMA and the conductive filler MXene resulted in a substantial increase in the sensitivity of the sensor,which was as high as 0.73 k Pa^-1.Meanwhile,the output voltage under palm pressing is 3 V,which is higher than PLLA and PAN systems.In a piezoelectric sensor,the higher the sensitivity,the more sensitive the sensor output signal is to changes in the input physical quantity.The sensitivity of sensor directly affects the accuracy and precision of measurement results.Therefore,the pressure sensor prepared by PMMA system has a faster response speed and can detect subtle output signals.The results show that this composite fiber has a wide range of applications in human body detection,signal detection and other fields.（4）For the polyvinyl chloride（PVC）system,PVC and GO were doped into the PVDF matrix,and we found that the piezoelectric output performance of the PVC system was significantly better than several other systems.The output voltage and current are 6 V and 3μA respectively when the palm is pressed,and up to 16V and 10V when the finger is tapped and the foot is pedalled.When the film is pasted on the finger,the output voltage of the sensor is 0.27 V,0.5 V and 0.81 V,respectively,when the finger is bent at 30°,60°and 90°.After 2000 cycles,the output voltage of the sensor has no obvious change,showing good stability.Therefore,this composite fiber shows great potential in human motion detection and other fields.In summary,the multifunctional composite films prepared by polymer blending and adding different fillers have superior performance.By adjusting the ratio of adding different fillers and blended polymers,we can prepare composite films with various features,such as piezoelectric,optical and other functions,which can meet the needs of different applications.