SPECTROFLUOROMETRIC DETERMINATION OF THE WATER-CONTENT OF THE SIO2 GELS DURING THE SOLVENT EXCHANGE IN PROPYLENE CARBONATE SOLUTIONS

Changes of water content were determined by spectrofluorimetric method s in three different types of SiO2 gels after solvent exchanges in PC, 0.2 M LiPF6-PC or 0.2 M LiBF4-PC. Pyranine was used as a photophysica l probe. The exchanges were carried out in bottles inside a glove-box flushed by dry nitrogen. It was found that the liquid inside the pores of the gels before the exchanges contained about 20-25 vol% of water. After the exchanges the water content decreased to about 4 vol%, The residual water could not be removed by subsequent exchanges. Possible causes for the presence of residual water are discussed.