Preparation And Properties Of Novel Poly(Arylene Piperidinium) Anion Exchange Membrane

Anion exchange membrane fuel cells(AEMFC)have been widely studied due to their advantages of low cost,high energy conversion efficiency and faster electrode reaction kinetics.Anion exchange membrane(AEM)is a key component of AEMFC,but AEM has low hydroxide conductivity and poor alkali stability,which limits its practical application.This thesis aims to address the issues of high water uptake and swelling ratio,and poor mechanical properties under the high ion exchange capacity(IEC)of the biphenyl ether-free main chain.We herein design and fabricate Non-ether poly(aryl piperidinium)by copolymerization of biphenyl,N-methyl-4-piperidone and 1,1,1-trifluoroacetone via a super electron nucleophilic substitution reaction.Two types of anion exchange membrane structures,partially fluorinated,multication cross-linked and free volume enhanced poly(arylene piperidinium)membranes were prepared in this thesis.The partially fluorinated backbone can help restrain membrane swelling,the multication cross-links may promote hydrophilic/hydrophobic microphase separation,and meanwhile restrain membrane swelling at less sacrifice of conductivity.Free volume enhanced structure can promote the formation of micro-phase separation in the membrane,thus the conductivity and dimensional stability can achieve a better balance.the main contents are as follows:1.The main chain structure(PBPiA)is synthesized by copolymerizing 1,1,1-trifluoroacetone,N-methyl-4-piperidone,and biphenyl,and cross-linking agent N1,N6-bis(6-bromohexyl)-N1,N1,N6,N6-tetramethylhexane-1,6-diammonium bromide(NBNTD)reaction for ionization.The resulting fluorinated cqPBPiA-71 membrane has a multi-cation structure that promotes microphase separation and forms a channel for ion conduction.It has an excellent OH-conductivity of 148.7 mS cm-1 at 80 ?(IEC=2.9 mmol g-1).Its swelling ratio is 33%at 80?,significantly lower than that of the non-fluorinated cqPBPi-71 membrane(58%)at the same temperature.After being treated in 1 M NaOH at 80? for 1714 h,the ionic conductivity of cqPBPiA-71 remained 85%.In addition,the peak power density of the H2/O2 fuel cell assembled with cqPBPiA-71 membrane at 60? is 208 mW cm-2.2.A series of PBPiA-AdA-x membranes were prepared by introducing large-volume,strongly hydrophobic ionic group adamantane(AdA)into the polyarylene piperidine skeleton through the Menshutkin reaction.Due to the strong hydrophobic and large adamantane structure,the volume characteristics can suppress the membrane swelling even at high IEC and improve the conductivity.When IEC is 2.2 mmol g-1,PAP-AdA-100 membrane shows a low swelling radio of 4.1%even at 80?,and its mechanical strength is 44 MPa.At 80?,the OH-conductivity of the PAP-IdA-71 membrane is 76.0 mS cm-1,while the PAP-AdA-100 with similar IEC valuesis 108.5 mS cm-1 at 80?.In addition,the results showed that the conductivity of PAP-AdA-100 membrane was greater than 95%after treatment for 1248 h in 80? in 1 MNaOH.