| dc.description.abstract | In this study, three series of hydrophilic monomers for preparation of ionic polymer for ion exchange membranes were developed.
In the first series, PNBC for medium temperature fuel cell exchange membrane was developed. First, new monomer NB-CIm-4 and NB-Hex were synthesized, and then the polymer PNBC was prepared via ring-opening metathesis polymerization (ROMP) with different ratio of these two monomers. The phosphoric acid-doped polymer PNBC was prepared by immersing the polymeric film into phosphoric acid solution. The membrane preparation of this new ionic polymer is under optimization.
In the second series, ionic polymer PSCN for alkaline fuel cell exchange membrane was developed. First, monomer VB-O8 and cross-linker DVB-O5 were synthesized and then the polymerization was carried out by reversible addition-fragmentation transfer polymerization (RAFT). The hydrophobic VB-O8 and cross-linker DVB-O5 were first polymerized, and then 4-vinylbenzyl chloride was introduced for co-polymerization. The new PS backbone was then imidazolized by methylimidazole to give the final ionic polymer. Then, alkalized PSCN polymer was obtained by immersing the polymeric film into KOH solution. To further improve the film softness, the hydrophobic styrene monomer with a longer branched alkyl chain (b-C8H17). Presently, PSCN-50 film exhibits conductivity up to 0.022 S/cm at room temperature.
In the third series, PNBCN for alkaline fuel cell exchange membrane was developed. First, new monomer BIm was synthesized by using neopentyl group as bridge between two imidazole units. Next, the new polymer NB-BIm was developed. Via ring-opening metathesis polymerization (ROMP) with different ratio of these three NB monomers, the new polymer PNBCN was developed. The alkalized PNBCN can be obtained by immersing the obtained polymeric film into KOH solution. The membrane preparation of this new polymer is under optimization.
In the fourth series, PBImNB for medium temperature fuel cell exchange membrane was developed. First, the previous series monomer NBIm (10%), BIm(40%) and dibromoalkane (50%) were first polymerized to give the new ionic polymer PBImNB. With the 10% NB unit, the new ionic polymer could be carried out second polymerization by ROMP or RAFT polymerization. The alkalized PBImNB ionic film was obtained by immersing the film into KOH solution. The phosphoric acid doped PBImNB film was obtained by immersing the obtained film into H3PO4 solution. The PBImNB membrane preparation for medium temperature fuel cell exchange membrane is under optimization.
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