Fabrication And Investigation Of Multifunctional And Flexible Conductive Polymer Composites

In recent years,flexible strain sensors with multi-functions(C-FSSF)based on conductive polymer composites have been employed in the medical field,health detection,electrical physiotherapy,human motion detection,human-machine interaction,electronics skin,electromagnetic shielding and nano-generators,showing great application prospects,which has attracted widespread attention from researchers.However,the preparation method of C-FSSF is still relatively single at present,and the strain sensing mechanism is not yet perfect;there are still a huge challenge in integrating the wearability,versatility with strain-resistance response performance of C-FSSF.In this work,designing the structure and conductive network of C-FSSF are used to tune the strain-sensing performance,wearability and versatility of C-FSSF,which provides a theoretical basis for the development and application of highperformance flexible wearable materials.The specific research content and main results are as follows:1.The ultra-high linear working range,excellent response stability and favorable oil/water separation capacity are achieved through constructing three dimensional(3 D)conductive network.Carbon black(CB)/(Polydimethylsiloxane)PDMS foam was fabricated through template method and ultrasonication.The sugar was selected as a template to fabricate pure PDMS foam,and then the CB nanoparticles can be anchored on the surface of PDMS foam through the swelling and ultrasonication,developing anexcellent conductive network.PDMS foam displays weak hysteresis,which is beneficial to resolve the urgent problems in the field of sensors.CB/PDMS foam material exhibits excellent strain sensing stability,ultra-high linear working range(～91%strain)and excellent durability.In addition,CB/PDMS foam material displays good ability of oil/water separation,which can be widely used to deal with oil pollution.2.The wide strain sensing range and high sensitivity of C-FSSF are realized through designing and constructing a "Layer by Layer" structure,which can balance the sensitivity and response range of C-FSSF to a certain extent;besides,C-FSSF can also be used to detect the ammonia(NH3)and temperature.The in-situ polymerizationultrasonication method was employed to fabricate polyaniline(PANI)/reduced graphene oxide(RGO)/stretchable fiber CPCs.PANI is anchored on the surface of stretchable fiber to develop a conductive layer through in-situ polymerization;then PANI/fiber is pre-stretched to generate some tiny cracks to improve the sensing stability;in order to further improve resistance response stability of sensors,RGO nanosheets are coated on PANI layer through ultrasonication technology.This special structure endows the sensors with high strain sensing sensitivity(Gauge factor,GF=10)and a wide working strain sensing range(0-200%strain),ultra-low detection limit(<0.1%strain),excellent durability(>1000 cycles)and excellent bending sensing performance,which can effectively monitor the human motions.In addition,C-FSSF shows good NH3 detection capabilities with a detection limit as low as 5ppm,which is of great significance for environmental detection;and C-FSSF can also be used to detect temperature change,showing interesting negative temperature effects(NTC).3.CB/PANI/thermoplastic polyurethane(TPU)electrospun film was fabricated through designing and constructing a "point to point"(PTP)conductive network.TPU electrospun film shows good flexibility,which makes it possible to fabricate wearable sensors.Meanwhile,the PTP conductive network endows the sensors with high sensitivity(GF=3030.8),large resistance response range(up to 600%),short response time(80 ms/95 ms),and ultra-low detection limit(0.03%strain)and excellent durability.These excellent sensing properties make it possible to effectively detect the human body’s movement and health.Meanwhile,the sensor material can also be used to detect toxic gases,which has great potential in the field of environmental detection.4.We prepared RGO/PANI/TPU film with high sensitivity through further regulating the response performance of the TPU-based electrospinning membrane sensor and increasing the functionality of the material.The large specific surface area of electrospun membrane can provide more sites for coating PANI particles.However,the sensing stability of the PANI/TPU film is greatly poor due to the relatively large rigidity of the PANI layer.Therefore,RGO nanosheets were introduced to bridge cracks of PANI to further improve the resistance sensing stability.Conductive TPU electrospun film possesses high sensitivity(GF=21188.7),ultra-wide sensing range(0400%strain),short response time(90 ms)and excellent durability(10000 stretching/releasing cycles).This excellent strain sensing performances endows CFSSF with excellent detection ability,which can be employed to detect complex human motions.Meanwhile,the TPU electrospun film is assembled into a triboelectric nano generator(TENG),which can effectively realize energy harvesting.In the twoelectrode working mode,the short-circuit current generated by TENG is 30 μA,and the open-circuit voltage is 528 V.Electronical devices based on electrospun TPU films can be applied in the field of strain sensors,energy harvesting and NH3 detection simultaneously,and they have shown great potential in self-powered and wearable electronic devices.5.A multifunctional sensor with excellent conductivity was fabricated through coating Ag nanoparticles(AgNPs)to the TPU electrospun film,subsequently spraying MXene nanosheets after plasma treatment(TAMF).TAMF shows excellent strain sensing performance,including low detection limit(0.1%strain),high sensitivity(GF=7853),wide working range(0-200%strain)and high permeability.Meanwhile,the electronic device possess an ultra-high conductivity(95238 S/m),therefore it can be used in electrical heater(80℃ at a voltage of 1 V)and electromagnetic shielding materials(108.8 dB).