Synthesis And Property Studies Of Alkaline Anion Exchange Membrane Based On New Hybrid Materials

With the emergence of environmental pollution and shortage of resources,researchers have shifted their attention to the development and utilization of new clean energy.Fuel cell is a power generation device that directly converts chemical energy existing in fuel and oxidant into electrical energy.High energy conversion rate,low environmental pollution and safety of operation are the foundation for its application.Among fuel cells,the alkaline fuel cell is the most promising one.As the core component of the alkaline fuel cell,the anion exchange membrane plays an vital role in conducting ions and separating cathode from anode.At present,to further improve the properties of polymer anion exchange membrane,the mainly used methods that focused by researchers include organic-inorganic hybrid strategy,crosslinking and direct polymerization routes.Organic-inorganic hybrid method is a simple and effective way which combines the advantages of organic phase and inorganic phase.In this thesis,the preparation methods and properties of organic-inorganic hybrid anion exchange membranes were mainly studied.Our studies include the following two parts:In the first part,we prepared a novel nanomaterial-the highly functional quaternized polyhedral oligomeric silsesquioxanes?QPOSS?by epoxide ring opening reaction,and introduced different content of QPOSS into the quaternized polysulfone matrix to fabricate a series of organic-inorganic hybrid anion exchange membranes.The research results found that the hydroxide conductivity was significantly improved with the increasing content of QPOSS in the composite membranes.Especially,the QPSU-3%-QPOSS exhibited 60%improvement in the hydroxide conductivity compared with the pure QPSU membrane.At the same time,the mechanical properties,oxidation and alkaline stability of the composite membranes have been improved in varying degrees after the doping of QPOSS.In the second part,we developed a new method based on mussel inspired chemistry to construct crosslinked hybrid anionic exchange membranes.The polydopamine functionalized reduced graphene oxide?PDArGO?firstly was prepared under a mild condition.And then different contents of PDArGO were introduced into the quaternized polysulfone?QPSU?with amino groups on the quaternized side chains to directly fabricate the crosslinked network in the hybrid anionic exchange membranes through the Michael addition/schiff base reactions in the simple alkaline conditions.Different from the general method for the preparation of hybrid anionic exchange membranes,in the synthetic process PDArGO not only is used as dopant,which can improve the content of the bound water in the membrane,but also is also regard as a crosslinking agent to form a micro-crosslinked structure between the inorganic phase and the organic phase.The special structure greatly improved the ionicconductivityofthecompositemembrane,especiallyforthe QPSU-1.5%-PDArGO membrane,the ionic conductivity could reach 61 mS cm^-11 at80^oC.In addition,the specific micro-crosslinking structure reduced the methanol permeability of composite membranes from 25.9×10^-88 to 3.8×10^-88 cm² s^-1,increased the Young's modulus from 868 to 1843 MPa.Overall,the balance between ionic conductivity and dimensional stability was achieved by using this method.