Preparation And Application Of Porous Elastic Conductive CNT/PU Nanocomposites

With the rapid development of nanotechnology and flexible wearable electronic devices,to cater to the increasing demand of human beings,the detection sensitivity,stretchability,wearability,comfort,portability,feedback speed of flexible wearable electronic devices,durability and manufacturing cost urgently need to be further optimized.In response to the above needs,this paper carried out research on elastic conductive polymer-based nanocomposites and obtained porous elastic carbon nanotube/polyurethane nanocomposites with high sensitivity and high stretchability,simple manufacturing process and low cost.First,using multi-walled carbon nanotubes(MWCNTs)as conductive nano-fillers and polyurethane(PU)as elastic polymer matrix,CNT/PU nanocomposite fibers with porous structure were prepared by the immersion precipitation phase inversion method.With the help of Fick's first law,the formation mechanism of the porous CNT/PU nanocomposite fiber was analyzed,and various process conditions were used to control the internal pore morphology of the porous CNT/PU nanocomposite fiber.When the strain amount is 100%,the resistivity change rate?R/R₀ of the porous CNT/PU nanocomposite fiber is 1420.3%,and the strain sensitivity coefficient GF is 14.2.Due to the existence of the internal pore structure,it is determined that the porous CNT/PU fiber should be a composite sensing mechanism combining geometric effect,breaking mechanism,crack propagation mechanism and tunneling effect.The stability,cycle performance and application of porous CNT/PU fiber were also studied,and the actual use value of porous CNT/PU fiber was demonstrated.Secondly,CNT/PU nanocomposite foams were prepared by three different methods:immersion precipitation phase inversion method,waterborne polyurethane mechanical foaming method and polyurethane AB material chemical foaming method.Observe the internal pores of the CNT/PU nanocomposite foam with the help of scanning electron microscope.Control the morphology of the pores by changing the process conditions.The?R/R₀ and GF of three CNT/PU nanocomposite foams were measured.As the strain degree increases,GF gradually decreases to about 1.Therefore,the resistance change mechanism of nanocomposite foams with different pore morphologies was analyzed.Among them,the CNT/PU nanocomposite foam should be a composite sensing mechanism combining geometric effect,crack propagation mechanism and tunneling effect;while small pore CNT/PU nanocomposite foam should be a combination of geometric effect,crack propagation mechanism and tunneling effect.The crack propagation mechanism and tunneling effect in nanocomposite foams only take effect in the initial stage.Finally,a planar array electrode sensor is prepared using CNT/PU nanocomposite foam,which can accurately detect the exact position of applied pressure(0.5?15N)and strain.