Preparation And Characterization Of Anion Exchange Membranes Based On Polyvinyl Alcohol

Polyvinyl alcohol(PVA) was used to prepare anion exchange membranes due to its high chemical stability, easy membrane casting, good mechanical propertoes, low methanol crossover and the cheap price. However, the applications of PVA are limited because its low conductivity and high swelling in water. Therefore it is needed to increase its conductivity and decrease the swelling of the membranes.Anion exchange membranes were prepared based on polyvinyl alcohol(PVA) in this work.(2,3-epoxypropyl)Trimethylammonium chloride(EPTMA) was used to quaternize PVA. The influence of the mole ratio of reactants, temperature and reaction time on the quaternization reaction was investigated. The reaction conditions were optimized via orthogonal experiments. A degree of substitution(DS), i.e.,69.6%, could be reached with a molar ratio of2.0:1.0for ETPTMA and PVA at50℃for26h.In order to decrease the swelling of PVA membranes. hydroxyapatite(HA) which exhibit excellent biocompatibility was used as additives to prepare hybrid membranes of HA/PVA and HA/QAPVA, respectively. Characterization of the hybrid membranes was made including the influence of the HA on water uptake, swelling, ionic exchange capacity, conductivity and mechanical properties. Pure PVA was almost soluble in water. Introducing HA in the membrane can decrease the swelling. The swelling ratio was10.5%for HA/PVA(wt(HA)=75.0%) and55.6%for HA/QAPVA. Pure PVA is an anionic insulator. The conductivity of HA/PVA was5.11X10"3S/cm with a HA weight percent of20.0%at50℃. However, the conductivity of HA/QAPVA membranes was lower than that of the pristine QAPVA membranes. Mechanical strength of the composite membranes was improved by HA doping. However the strain of the membrane was decreased.