Study On The Synthesis And Properties Of Tetrazole Functionalized Graphene And Composite Proton Exchange Membranes

Perfluoroethylene sulfonic acid membrane?Nafion?has not been commercially applied in fuel cells under the limitations by its strong water dependence and low working temperature.So,developing the novel proton exchange membrane with protogenic proton conductivity and low relative humidity?RH?has been a research hotspot.Self-standing membrane was synthesized by condensation,sol-gel process using polysiloxane as backbone precursor in this work.Also,graphene oxide?GO?was prepared by oxidizing natural flake graphite and mechanical stripping using ultrasound.Composite proton exchange membrane was also prepared by in-situ polymerization using modified functional GO.The specific work is as follows:Firstly,macromonomer?GPTMS-TZ?was obtained by condensation from3-glycidyloxypropyltrimethoxysilane?GPTMS?and 5-amino-1H-tetrazole?5-ATZ?.Self-standing membrane?Pseudo-polyethylene oxide network?was prepared by sol-gel process and polymerization in presence of GPTMS,GPTMS-TZ,phosphous and hydrochloric acid.Its structure was characterized by DSC,SEM,FT-IR,XPS,XRD,TG-DTG,²⁹Si CP MAS NMR and³¹P CP MAS NMR.Proton conductivity???was examined by electrochemical AC impedance method.The results showed that when n?H₃PO₄?:n?GPTMS-TZ?=3,?=0.0658 S/cm under n?GPTMS?:n?GPTMS-TZ?=3:7,110?and anhydrous state.?=0.1065 S/cm under n?GPTMS?:n?GPTMS-TZ?=2:8,70?and hygrometric state.Secondly,azide GO from 3-chlorpropyltrimethoxy silane condensed with polar group in the surface of GO was click-modification by alkynyl 5-aminotetrazole and functional GO?GO-Click-TZ?was obtained.And,another functional GO?GO-PTMS-TZ?was obtained through GO modified by 5-ATZ,3-chlorpropyl trimethoxy silane as crosslinker.Their structures were characterized by TG?Raman?XRD?XPS?SEM?TEM and FT-IR.The properties were determined by the dispersion test.At last,functional GO was dispersed in the solution of macromonomer?GPTMS-TZ?,1,8-bis?trimethoxy?octane?Si-C₈?and tetraethylorthosilicate?TEOS?,sol-geled and in-situ polymerized on the polytetrafluoroethylene film.The composite proton exchange membrane was obtained through aging.The influence of functional GO dopping on proton conductivity was studied in the range of temperatures.The results showed that in an anhydrous state,the proton conductivityof undoped,0.5wt%GO-PTMS-TZ and 0.5 wt%GO-Click-TZ film was 8.814?10^-3,4.275?10^-33 and2.055?10^-33 S/cm at 110?,respectively.This illustrated that the doping of functional graphene did not improve proton conductivity.