Fabrication And Performance Of Polymer Fiber/Film Based Conductive Composites

In recent years,conductive polymer composites（CPC）have shown great application prospects in the fields of electromagnetic shielding,stress/strain sensors,human motion detection,medical field and energy,which has attracted extensive attention from researchers.However,the preparation method of CPC is still relatively single at present,and the conductive network needs to be tuned.Even though the sensing and electrolyte material based on CPC have been investigated systematically,the mechanism of electron/ion transfer mechanism is not perfect yet;therefore,it is still a big challenge to achieve conductive composites based on polymer fiber/film with excellent performances and investigate the mechanism of conductive network construction and external field response.In this work,the methods of electrospinning,solution mixing coupled with ultrasonic treatment were employed to fabricate the CPC material;meanwhile,the sensing and electron/ion transmission performance of CPC were improved through designing and tuning the conductive network,which provides a theoretical basis for the development and application of high-performance flexible CPC materials.The main research content and main results are as follows:1.CPC material with excellent electrical conductivity was achieved by decorating the conductive fillers on the elastic fibers with helix structure through using the technology of dipping and ultrasonication.Firstly,poly（3,4-ethylenedioxythiophene）poly（styrenesulfonate）（PEDOT:PSS）/fiber composites were fabricated through dipping the fibers into the PEDOT:PSS solution;then the carbon black（CB）,reduced graphene oxide（r GO）and carbon nanotube（CNT）are anchored on PEDOT:PSS/fiber through ultrasonication,and the corresponding sensing properties are detailly investigated to prepare the strain sensors with outstanding response performances,which can be used in application scenarios.The research results show that the CPC material possesses low detection limit,fast response time and good sensing stability.Human body motion characterization shows that the sensor material based fibers can meet the needs of human body posture monitoring in different application scenarios.2.Conductive composite fiber membrane with a"sandwich"structure based on thermoplastic polyurethane（TPU）/r GO/TPU was fabricated and the microstructure of conductive network was investigated in detail.TPU is selected as the flexible base material for strain sensors due to its excellent stretchability.TPU fiber film obtained by electrospinning method was employed as matrix owing to their high stretchability.Due to the difference in elastic modulus of r GO and TPU fiber film,the conductive network of r GO/TPU CPC will be destroyed within a controllable range when stretched,forming crack structure,thus improving the sensing of strain sensors.Finally,the strain sensor based on conductive r GO/TPU fiber film shows wide strain range.Meanwhile,the sensing materials also possess good sensing stability,low detection limit and fast response time.3.The 0-dimensional CB nanoparticles are coated on the surface of TPU electrospun film through the method of ultrasonication,constructing excellent conductive network.TPU electrospun film material has good stretchability,which endows the sensor high flexibility.Meanwhile,the sensor material exhibits high sensitivity,short response time,and excellent durability.The flexible and stretchable strain sensors were used to detect human movement and monitor health situation owing to the excellent sensing properties.4.Firstly,TPU material was selected as the composite phase,and TPU-based composite electrolyte were fabricated through solution casting method,respectively.The influence of different ratios on the microstructure and performance of electrolytes is also discussed in detail.Through experiments,it can be known that the introduction of TPU can improve the mechanical and electrochemical properties of the composite electrolyte,thus improving the charge and discharge performance and cycle stability of the battery.In addition,the full battery prepared by the Li_6.4La₃Zr_1.4Ta_0.6O₁₂（LLZTO）/Polyoxyethylene（PEO）/TPU composite electrolyte can be stable after more than 100 cycles under the experimental conditions of 60℃and 0.2 C,and the specific capacity remains above 150 m Wh/g.