Study On Carbon Nanotubes Conductive Membranes Based On Ionic Liquid

Conductive materials are widely used in electrochemical and biomedical fields.Carbon nanotubes?CNTs?/polymer composites combine the remarkable electrical,thermal and mechanical properties of CNTs with the elasticity and softness of polymer matrix.Cellulose is the most abundant natural high-molecular polymer.Using cellulose instead of polymer preparing CNTs/cellulose composites can reduce the environmental pollution caused by difficult degrading of polymer.However,CNTs are easy to form agglomerates during mixing with the cellulose,which results in a weak interaction between CNTs and cellulose.The weak interaction limits the performance of composite materials.Promoting the dispersing of CNTs is one of the most meaningful ways to improve the performance of composite materials.In this paper,1-ethyl-3-methylimidazolium diethyl phosphate?EmimDEP?was used as solvent to prepare MWCNTs/cellulose composite membrane.1-butyl-3-methylimidazolium tetrafluoroborate?BmimBF₄?,sodiumdodecylsulfate?SDS?and1-hexadecyl-3-methylimidazolium bromide(C₁₆mimBr)were applied as additives to promoting the dispersing of MWCNTs,respectively.The major research results are shown as follows:The membrane solution was prepared by mechanical agitation.The rheological properties and the dispersing of MWCNTs of the membrane solution were studied by rheometer and optical microscope.The results showed that the membrane solution is a non-Newtonian fluid,possessing the shear-thinning characteristic.With the increasing of MWCNTs qualities,the dispersion of MWCNTs became worse.The introducing of additives promoted the dispersing of MWCNTs obviously,which enhanced the entanglement effect between cellulose and MWCNTs and increased the viscosity of membrane solution.The effect of additives on the dispersing of MWCNTs followed the order of SDS>C₁₆mimBr>BmimBF₄.The composite membrane was prepared by knife coating.The interaction between MWCNTs and cellulose became worse with the increasing the MWCNTs qualities.There were two results for this phenomenon.One is the mechanical performance of composite membrane decreased.Another is the conductivity of composite membrane free surface increased owing to the increasing of MWCNTs qualities on the free surface.The thermal stability and specific capacitance of composite membrane increased with the increasing of the MWCNTs qualities.The composite membrane can be used as a capacitor electrode by further improving and regulating the performances of composite membrane.The introducing of additives enhanced the strength and uniformity of interaction between MWCNTs and cellulose,which caused two results.Firstly,the mechanical performance and thermal stability of composite membrane increased.Secondly,the conductivity of composite membrane free surface increased owing to the promoting of MWCNTs uniformity dispersing on the free surface.According to the effect of three kind of additives on the dispersing of MWCNTs,the improvement of composite membrane performance followed the order of SDS>C₁₆mimBr>BmimBF₄.