Preparation And Properties Of Pressure Sensor And Electrode Based On High Strength PBO Nanofiber Film

In recent years,various electronic components have been integrated on clothing products to manufacture intelligent wearable products,provide great convenience for users’daily life.The intellectualization of wearable products has become the mainstream of evolution direction of clothing at present.In order to provide users with higher comfort and convenience,the flexibility of intelligent wearable products has become a vital proposition in this field.Among them,the flexibility of transmission circuit and sensor has been achieved,while the flexibility of energy storage elements is still a challenge.Because the electrolyte and diaphragm in capacitors are generally flexible.The electrode has also become the key factor to determine the flexibility of energy storage equipment.In addition,the strength of the electrode is crucial to the service life and application range of energy storage equipment.Thus,how to improve the flexibility and strength of the electrode has become the forefront and hotspot of intelligent wearable research.PBO(poly-p-phenylene benzobisoxazole)fiber is a kind of organic fiber,which has the highest strength and the best heat resistance among all the organic high-performance fibers at present.In addition,PBO fiber has excellent chemical stability.Except for the mixed acid solution of methanesulfonic acid and trifluoroacetic acid,there is almost no solvent to dissolve it.However,PBO fiber has a diameter of about ten microns,which limits its application in the field of nano materials.Based on these facts,PBO nanofiber film can be prepared by dissolving PBO fiber in the dissolution system composed of trifluoroacetic acid and methanesulfonic acid.Which can be used as the high-strength flexible electrode substrate.However,because PBO fiber is an insulating material,it needs to be compounded with other conductive materials to obtain conductivity.Silver has excellent conductivity,good stability and oxidation resistance.Silver nanoparticles(Ag NPs)can be evenly mixed with other solvents after stirring and ultrasonic treatment,which is an ideal additive for the preparation of the composite electrode.In this work,Ag NPs was added to PBO dispersion to prepare high-strength conductive composite film,which can be used for the electrode collector.Polyaniline has been one of the most popular materials for manufacturing supercapacitor electrodes,because it not only has high capacitance,but also has the advantages of low manufacturing costs and simple synthesis method.Carbon nanotube(CNT)is a new star in the field of materials.This one-dimensional nano material has excellent electrical and mechanical properties at the molecular level.It is an ideal candidate material for manufacturing electronic components and mechanical reinforcements.Here,CNT is dispersed in the ethanol solution of aniline.Through the hydrothermal reaction with simple process and strong controllability,polyaniline doped with CNT is loaded on the surface of PBO/Ag nanofiber composite film to prepare high-strength flexible electrode.The main research contents of this subject are summarized as follows:1.Preparation and properties of ultra-thin and high strength PBO nanofiber filmUltra-thin and high strength PBO nanofiber films were prepared by high modulus PBO fiber as raw material.The additive amount and dissolution time of PBO fiber were set as variables,which have a great influence on the strength of the film.Taking the breaking strength and Young’s modulus as the evaluation criteria,the optimal parameters of preparation process of the PBO nanofiber film were determined by orthogonal experiment.The micro morphology and color of the PBO nanofiber film were observed.The results showed that with the increase of the additive amount of PBO fiber,the color of the PBO nanofiber film became darker;The size of PBO nanofibers became smaller and the surface morphology of PBO nanofiber film became smoother with the increase of the dissolution time.Fourier transform infrared spectroscopy showed that PBO nanofibers had similar absorption peaks with PBO fibers,and the PBO nanofibers retained the basic chemical structure of PBO fibers.X-ray diffraction patterns showed that the higher the additive amount of PBO fiber,the higher the crystallinity was.The testing results of mechanical properties show that the breaking strength of nanofiber film with different PBO content first increases and then decreases with the increase of dissolution time.When the content of PBO was 2.8 g/L and the dissolving time was 40 hours,the PBO nanofiber film had the best mechanical properties,of which the breaking strength and Young’s modulus were up to 683 MPa and 12.05 GPa.2.Preparation and properties of ultra-thin,high strength and high conductivity PBO/Ag nanofiber composite filmUsing PBO dispersion and Ag NPs as raw materials,the effect of Ag NPs additive on the properties of composite film was studied by single variable method.The testing results showed that when the additive amount of Ag NPs is 10%,the nanofiber composite film had a breaking strength of 239 MPa,a young’s modulus of 5.91 GPa and a conductivity of 401.6 S/cm,which is much higher than the reported high-strength conductive composite film.After 300 times folds in half,the PBO/Ag nanofiber composite film still had high conductivity and showed good mechanical durability;In addition,after soaking in six kinds of common solutions for 24 hours,the composite film still maintained high conductivity and showed good chemical stability.Combined with the surface morphology and contact angle testing results,the surface of PBO/Ag nanofiber composite film with 10%additive amount of Ag NPs presents a nano-scale papillary structure like the surface of lotus leaf,and the contact angle is up to 135°.This strong surface hydrophobicity also accounted for the excellent anti-fouling ability of PBO/Ag nanofiber composite film.Based on the excellent comprehensive properties of PBO/Ag composite nanofiber film,it showed great application potential in detecting human physiological signals and monitoring movement.It was assembled into a pressure sensor,which showed high sensitivity and linear output ability in the pressure range of 0～85 k Pa.Good sensing stability was proved in the stability test.It also exhibited high accuracy and sensitivity through monitoring of physiological signals and human joint movement.3.Preparation and properties of high strength PBO/Ag@PANI/CNT flexible electrodeSelecting polystyrene monomer as raw material,carboxylated carbon nanotubes were mixed into aniline aqueous solution,and CNT doped polyaniline was coated on the surface of PBO/Ag nanofiber composite film by hydrothermal reaction to prepare high-strength PBO/Ag@PANI/CNT flexible electrode.Setting the CNT doping amount as the only variable and taking the electrochemical performance as the evaluation index,the results show that when the CNT doping amount is 30%,the electrode has the best electrochemical performance.In the test of three electrode system,the maximum area specific capacitance is 6885.13 m F/cm~2,and the maximum area specific capacitance measured under two electrode system is 6237.25 m F/cm~2 and the maximum energy density is 546.32μWh/cm~2,maximum power density up to 11982.74μW/cm~2.In addition to excellent electrochemical performance,its excellent mechanical strength and flexibility give it greater application potential and wider application space.