Preparation Of Polypyrrole-coated Textiles Via Low-temperature Interfacial Polymerization For Flexible Electronics

In recent years,flexible electronics has attracted tremendous interest of researchers and industry.The flexible electronic devices could function by sewing on the clothes,attaching to the skin,or even implanting into the body.Because of its light weight,softness and comfort,the textile has been considered as an ideal alternative material to serve as the substrate for flexible electronic devices.However,to realize the application of textiles in flexible electronics,it is urgent to endow them with specific functions,such as conduction,sensing and energy storage,which are necessary for flexible electronic devices.Polypyrrole(PPy)is a kind of commonly used nontoxic conductive polymer,which can be in situ synthesized on different substrates by low-temperature interfacial polymerization approach,forming a dense PPy coating layer.In this thesis,PPy is polymerized on different fabrics at low temperature to verify the general applicability of the preparation method.According to the characteristics of fabrics,flexible strain sensor and flexible supercapacitor were prepared on textiles,respectively.The thesis mainly contains the following parts:1.Preparation of polypyrrole-modified stretchable textile via low temperature interfacial polymerization for flexible strain sensorIn this part,PPy was successfully polymerized on polyester/spandex,cotton and silk textiles via the low-temperature interfacial polymerization method.An elastic polyester/spandex textile with optimal tensile property was selected to prepare a strain sensor with a wide detection range and high sensitivity for human motion and respiration monitoring.Scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR)and thermogravimetric analysis(TGA)data prove that PPy is densely coated on the textile.The resistance of the as-prepared textile is 21.25 ? cm-2.The PPy-coated textile can be used as a conductor to light an LED lamp.The conductive textile can tolerate 180° bending and 500 times bending/twisting without significant change on the resistance.The linear stretch range of the sensor is 0 to 71% with the GF 0.46.The resistance change of the sensor is inversely correlated to the applied strain.After 200 times tensile-recovery cycles at 26% strain,the current of the sensor does not change significantly.The body or clothes-attached sensors can sensitively detect the fingers/elbows/knees bending and distinguish deep,normal,and rapid breath of volunteers.This work not only further confirms the universality of the PPy lowtemperature interfacial polymerization approach for textiles,but also provides a simple and feasible method for the preparation of PPy-coated textile for flexible strain sensor.2.Preparation of polypyrrole-coated textile via low temperature interfacial polymerization for flexible supercapacitorsIn this part,Lycra/nylon textile was selected as the substrate material for the lowtemperature interfacial polymerization of PPy.SEM,FTIR and TGA data prove that PPy is densely coated on the textile with a resistance of 10 ? cm-2.The textile was utilized as both current collector and active material to construct a sandwich-structured all-solidstate supercapacitor.When the charge and discharge current density is 1 m A cm-2,the capacity of the supercapacitor is 7.5 m F cm-2.The capacitance retention rate of the supercapacitor is 76.8% after 500 charge-discharge cycles.The device can withstand multiple bending and twisting.After twisting 100 times,the capacitance retention is 90%.After bending 100 times,the capacitance retention rate was 94.2%.Stretching can lead to a sharp drop in capacitance,which may be caused by the failure of the solid electrolyte to match the stretching of the flexible electrode.This work further confirms the general applicability of the PPy low-temperature interfacial polymerization to textiles.The feasibility of PPy-modified textiles for stretchable supercapacitor was also explored to provide useful information for the future works.In this thesis,the PPy low-temperature interface polymerization method is combined with a variety of textiles to build a flexible strain sensor and an all-solid-state supercapacitor with good performance.This thesis may expand the application of PPycoated textile in the field of wearable electronics.In the appendix of the thesis,the feasibility of preparing flexible supercapacitor with silk fibroin as electrolyte was also explored to reveal the influences of lithium ion on the secondary structure of silk fibroin and the final performance of the devices.