Preparation And Properties Of PGA Nanofiber Modified Sulfonated Polyethersulfone Proton Exchange Membrane

Proton exchange membrane fuel cell（PEMFC）is a device that can convert chemical energy into electricity directly,which has high power density,high energy efficiency,environmental friendly and quickly start.Therefore,PEMFC is a new way of energy utilization.Proton exchange membrane（PEM）is one of the core components,which has the effects of transmiting protons and preventing fuel penetration,and its performance determines the performance of the battery directly.Due to the expensive cost,high temperature and humidity lower proton conductivity,high methanol permeability of perfluorosulfonate membrane,the wide application of proton exchange membrane fuel cell was seriously hindered.So the high performance,cost-effective PEMs has been becoming the current research hot topic.In recent years,the nanofibers with large specific surface area,high length-diameter ratio,better mechanical,has been used in PEMs to improve the mechanical properties and proton conduction performances.In this paper,in order to enhance the performance of PEMs a new method of constructing proton transport channels via introducing PGA nanofibers into SPES has been found.The main works are as follows:Poly glutamic acid（PGA）nanofiber mats are prepared by solution blowing process,the influence of speed of drafting wind and the PGA contents is analyzed.The analysis results of FESEM,FTIR,XPS and TGA showed that with the increase of drawing velocity,the formability of nanofibers increases gradually,with the PGA content increasing,surface defects of nanofiber decreases.The electrochemical tests show that the proton conductivity of PGA nanofibers increases gradually with the increase of temperature and humidity,and with the increasing of the PGA content the proton conductivity of nanofibers also increase gradually.Inspired by the proton-conducting mechanism in some organisms where amino acids simultaneously act as acceptors and donors in proton conduction,poly-γ-glutamic acid（PGA）nanofibers（NFs）were designed to fabricate amino acid arrays as efficient proton-conducting channels for proton exchange membranes（PEMs）.These NFs were incorporated into the sulfonated poly（ether sulfone）（SPES）to prepare PEMs.The NF composite membrane with 30wt%NFs exhibited the highest proton conductivity and selectivity among all the composite membranes.In addition,the methanol crossover of the composite membranes was reduced two orders of magnitude compared with that of pure SPES membrane.The oriented PGA nanofibers are prepared by auxiliary electrode electrostatic spinning technology.And the oriented PGA nanofibers are impregnated into the SPES formed the nanofibers composite PEM.The composite membranes exhibited unexceptionable protons conduction performances.The analysis results of FESEM,XPS,XRD and TG showed that oriented PGA nanofibers was successfully,and has good orientation and thermal stability.The electrochemical performance test shows that the oriented PGA nanofibers composite membrane has best proton conductivity,and proton conductivity is 0.368 Scm^-1 in 100%humidity and at 80℃.