PREPARATION AND STRUCTURE/PROPERTY RELATIONSHIP OF POLYSULFONE ANION-EXCHANGE MEMBRANES

Polysulfone (PSF) was chloromethylated using 1,4-bis(chloromethoxy) butane (BCMB) without carcinogenitic toxicity as chloromethylation reagent,resulting in chloromethylated polysulfone ( CMPSF).The chemical structure of CMPSF was characterized by FTIR,1H-NMR and chemical analysis method.The effects of main factors on the chloromethylation reaction of PSF were examined.By using three tertiary amines,triethylamine ( TEA ),tripropylamine ( TPA ) and tri-n-butylamine ( TBA ),the quaternization reaction of CMPSF was carried out,respectively,and then the crosslinking reaction was performed with 4,4′-bipyridine as crosslinker,obtaining polysulfone anion-exchange membrane ( PSFAEM).The main properties of PSFAEM were determined including ion-exchange capacity ( IEC ),water content ( WC ) and membrane resistance (Rm).The experimental results show that the chloromethylation reaction of PSF with BCMB can be carried out favorably,and CMPSF with a chloromethylation degree of 1.75 mmol /g can be obtained as with chloroform as solvent and SnCl4 as Lewis catalyst.The properties of PSFAEM such as IEC,WC and Rm are closely related with quaternization time and the structure of the tertiary amine.In the same quaternization time,the anion-exchange membrane PSFAEM prepared with TEA,in whose molecule the number of carbon atom in alkyl group on N atom is small,has relatively high IEC,WC and lower Rm.As using the same tertiary amine,the IEC and WC of PSFAEM are increased with increasing the quaternization time,and Rm decreases.