Interactions in water-THF binary mixture by contact angle, FTIR and dielectric studies

Contact angle, dielectric and IR studies of aqueous tetrahydrofuran (THF) are carried over the entire concentration range. IR studies indicate the formation of blue-shifted hydrogen bonds between water and THF molecules over the entire concentration region. On addition of small quantities of THF to water, THF molecules enter into the hydrogen bonded water network forming clathrate like complexes. Concentration dependent wetting of aqueous THF over various substrates is also reported. The effect of clathrate formation on the wetting properties of the substrate has also been explored. The clathrate structures formed are seen to influence the wetting properties on moderately hydrophobic substrates like Indium tin Oxide (ITO), Cubic Bismuth Zinc Niobate thin film on sapphire substrate (CBZN), Yttrium-stabilized zirconia (YSZ), Strontium Titanate (STO) and Si wafer. Contact angles decreases with an increase in THF concentration except in the region (0.03 ≤ XTHF ≤ 0.05 and 0.07 ≤ XTHF ≤ 0.09) where clathrate structure appears and hence no change of contact angle is seen.