Preparation And Properties Of Anion Exchange Membranes Containing Multi-Biphenyl Units

The challenge in developing high-performance anion exchange membranes（AEMs）is to achieve high ion conductivity,while maintain sufficient alkaline and mechanical stability.In this thesis,we designed and synthesized a new aromatic monomer with multiphenyl and brominated branch units（BBTP）,and two new types of aryl ether-free AEMs were prepared from BBTP.The specific research content is as follows:1、Design,synthesis and properties of multi-piperidium side-chain-type AEMs based on BBTPThe precursor polymers（PTPDP-x-Br）were synthesized from BBTP,bibenzyl and trifluoroacetone by superacid-catalyzed polyhydroxyalkylation reaction.Then,the target polymers（QPTPDP-x-Br）were prepared by the quaternization reactions between PTPDP-x-Br and N-methylpiperidine.Finally,multi-piperidium side-chain-type AEMs（QPTPDP-x-OH）were obtained through solution-casting method.QPTPDP-x-OH membranes exhibited high hydroxide conductivity up to161.5 m S/cm at 80°C,and excellent alkaline stability with the conductivity loss below 20%after soaking in 5 M Na OH at 80°C for 1200 h.In additions,the QPTPDP-30-OH membrane achieved a peak power density of 407.8m W/cm² at a current density of 905 m A/cm² in H₂-O₂ fuel cells at 60°C.2、Preparation and properties of cross-linking type AEMs based on PBTPThe PBTP polymers were synthesized from BBTP and trifluoroacetone by superacid-catalyzed polyhydroxyalkylation reaction.The chloromethylated SEBS（SEBS-Cl）was prepared from commercially available poly(styrene-b-（ethylene-co-butylene）s（SEBS）.Then a series of novel crosslinked AEMs（CQPTP@SEBS-ab C-OH）with different degrees of crosslinking were prepared from PBTP and SEBS-Cl,using N,N,N’,N’-tetramethyl-1,6-diamino-hexane as a crosslinker.Scanning electron microscope images showed that the compatibility between cross-linked components became poor with the increasing degree of crosslinking.Atomic force microscope images indicated that there was obvious phase separation in CQPTP@SEBS-2210-OH.CQPTP@SEBS-3110-OH has a conductivity of up to 169.1 m S/cm and a swelling rate of 52%at 80°C.The conductivity loss of CQPTP@SEBS-13C-OH and CQPTP@SEBS-22C-OH was lower than 30%,after treating with 2M Na OH at 80°C for 1680 h.