Influence Of A New Roughening Process Of Base Membrane On Interface And Properties Of IPMC

As a typical kind of flexible intelligent materials,Ionic Polymer-Metal Composite(IPMC)with the outstanding characteristics of low applied voltage,light weight,good flexibility as well as large deformation has attracted increasing attention in many fields during recent decades.Improving the fabrication process and preparing IPMC materials with high performance is one of the foundation and key issues to promote its application.Rough interface and deep penetration of the electrode can ensure effective combination between the electrode and the membrane to improve the performance of IPMC.However,there are still many problems in the existing fabrication process of IPMC,such as shallow penetration of the electrode,complex and interlaced branches of dendritic electrodes,unmanageable personal error,high cost and difficult implementation of automation and so on,which make it far away from practical engineering application.In this dissertation,a novel method for roughening the membrane will be proposed,and its influence on the interface electrode and performance of IPMC will be displayed.The detailed work is as follows:Firstly,a novel method for roughening the membrane using microneedle is proposed.The microneedle roller was assembled with a 3D-printed shell and the degree of roughening of the membrane was controlled by the load and the rolling cycles.At the same time the roughening cycles were automatically recorded by connecting an infrared digital display counter.An automatic roughening model was also proposed to provide a scheme for batch roughening of the membrane.Then,a lot of experiments were carried out to explore the roughening parameters.The surface morphology of the roughened membranes processed by different load and rolling cycles were characterized by metallographic microscope and the degree of roughening for the base membrane was statistically analyzed by ImagJ.Studies have shown that the Nafion membrane displayed insufficient,excessive roughening or severe curl because of too improper choice of load and rolling cycle,which would lead to severe destroy of the surface electrode.The appropriate range of load and rolling cycle parameters were selected on the basis of a large number of experiments and 16 sets of samples were successfully fabricated.The optimization of roughening parameters was studied in this range.Furthermore,from the perspective of the influence caused by area variation in the fabrication process,we firstly regulated the sequence of the process to roughen the substrate membrane after the first ion-exchange step and a new set of process was developed in combination with the microneedle roughening process.On this basis,IPMC with deep needle electrode,whose average penetrated depth could reach up to about 80 ?m,was successfully prepared.The morphology of the IPMC interface electrode was characterized by scanning electron microscopy,showing that the infiltrated needle-electrode was simple without complicated branches,which reduced the rigidity of the material and greatly improved the electro-mechanical properties of the material.The electrochemical and electro-mechanical performance of IPMC before and after improvement for the process were tested under the same conditions.It was found that with the new set of fabrication process,the specific capacitances were about four to five times higher and the deformation was about two to four times higher compared than that for samples fabricated with the traditional fabricated process and the samples also had high-frequency response characteristics,which enabled effective operation at20 Hz.Finally,the microneedle roughening process was used to improve the comprehensive driving performance of the thick IPMCs,which was compared with the IPMCs with the same thickness fabricated by sandpapering.The results showed that the deep needle electrode fabricated by the microneedle roughening process improved the performance of IPMC effectively.