Preparation And Piezoresistive Properties Study Of Flexiable Porous Conductive Polymer Composites

Flexible porous conductive polymer composites(PCPCs)would exhibit remarkable piezoresistive properties,which hold promising applications in the area of wearable devices.The preparation methods of PCPC are classified into “ice solid template” method and “dip-coating” method.Although those materials from these two methods have low density and cyclabe compression properties,but their strain sensitivity coefficient GF was as low as 3.Herein,we report a new method of preparation flexible PCPCs through high internal phase emulsion templates method,which contains GO aqueous solution as the dispersed phase and soft monomer mixture as continuous phase.During polymerization,GO particles were reduced synchronously by an environmental and effective reagent Vitamin C in the aqueous phase.The reduced GO(rGO)attained improved conductivity and increased hydrophobicity,leading to their attachment at the inner wall and increase the conductivity.The aqueous phase was removed by drying after the polymerization,and flexible piezoresistive sensitive PCPCs with rGO covering framework were obtained.GO particles with 0.5-5?m and 2-10?m sheet size were employed as precursor of conductive fillers,respectively.The reduction reaction of GO particles was followed.Then,the effects of GO loading,type of surfactants,and surfactant loadings on the microstructure,mechanical properties,electrical conductivities and piezoresistive properties of PCPCs were investigated.The followings are concluded:1.During the polymerization,GO can be effectively reduced into rGO concurrently by Vitamin C.2.When the sheet size of GO is in the range between 0.5 and 5 ?m:(1)Synchronously reduced GO particles covered the cavity wall surfaces of material,and strengthened the walls.It led to the PCPC with closed cell structure.(2)The conductivities of all PCPCs increase with the compressive strain,and thus these materials have a piezoresistive property.(3)With the increase of GO loading from 0 wt% to 0.91 wt%,the average pore diameter decreased,while remained in the range between 37 ?m and 87 ?m.At the same time,the conductivity of PCPC increased gradually.GF value exhibits V shape,but the maximum value was only 1.03.(4)With the increase of span80 loading from 8 wt% to 23 wt%,the average pore diameter decreased slightly,the specific surface area increased,the filler surface density decreased.At the same time,the conductivity of PCPC decreased gradually.GF value exhibits V shape,but the maximum value was only 1.22.(5)After the replacement of Span 80 with Hypermer A70,the influences of A70 dosages on pore size follows similar rules as that of Span 80.However,due to the fact that Hypermer A70 is more surfactant effective than Span 80,the prepared PCPCs had significantly reduced pore size and conductivity.GF value of A70 based PCPCs were as low as 0.2.3.The replacement of 0.5-5?m GO with 2-10?m GO improved the electromechanical integrity of PCPC: in the vicinity of conductive percolation threshold,the CPCF has highest GF of 6.0 within 0-5% strain range and piezoresistive stability,demonstrating its high strain sensitivity and promising applicability in strain sensors.