Structure Nature And Ion Transport In Ion Exchange Membrane

Ions exchange membranes(IEMs)are essential components of clean and high efficient technologies for energy generation and storage,water and wastewaters treatment,food processing,chemical productions,sensors,and drug delivery.Control of morphological structure nature has proven to improve significantly the physical and electrochemical properties of IEMs.This thesis focuses on constructing IEMs with sophisticated structure morphologies and examines their ion transport toward improved selectivity and efficiency.In this thesis,we investigated different morphological structures where layered,phase separated and hierarchical structured morphologies are constructed in IEMs for potential application in polymer electrolyte fuel cell(PEMFC)whereas porous hierarchical structured anion exchange membranes are examined for acid recovery.Sandwich structured proton exchange membranes were prepared through sandwiching a thin hydrophobic polymer as inner layer between sulphonated polymer as outer layers.The obtained membranes showed superior fuel cell performance and selectivity because they exhibited very low methanol permeability compared to the pristine SPPO membrane and Nafion(?).Owing to its dibasic nature,sulfonyl-amino-tetrazole(SAT)groups were synthesized and applied in proton exchange membrane(PEM)to construct low barrier hydrogen bond as a suitable proton transport pathways for PEM in fuel cell operating at low hydration.The transport properties were investigated by using pulse field Gradient NMR spectroscopy(PFG-NMR).The results evidenced the presence of low barrier hydrogen bond network and the obtained membranes exhibited interesting proton conductivity at low hydration.Highly charged hierarchical porous anion exchange membranes(AEMs)were prepared by coupling quaternized polymer and an organosilane ionic liquid(IL).The obtained AEMs exhibited high selectivity,good ion flux and thus excellent performances for acid recovery.The zwetterionic pores were constructed and examined toward enhanced ion flux in hierarchical structured porous AEMs.To construct well aligned phase separated morphologies in AEMs,tetrazole moiety was used in formation of long range hydrogen bond network which in turn facilitates the alignment of functional groups and thus leads to formation of well defined phase separated as shown by atomic force microscopy(AFM),transmission electron microscopy(TEM)and small-angle x-ray scattering(SAXS).The membranes showed broad morphology structure of wide and narrow phase separation.The AEMs supported by tetrazole network exhibited good hydroxide conductivity(ca.>10mS/cm)at 25? under low hydration.The results showed interesting features of tetrazole moiety to regulate the hydration and dimensional stability of AEMs.The obtained results in this thesis provide new routes which will advance the design and fabrication of IEMs for energy generation and separation processes.