The influence of different ions on the phase separation of poly (Vinyl Alcohol) and poly (Sodium 4-Styrene Sulphonate) in aqueous solution

In aqueous solution the phase separation behavior of mixture of pva-pssna has been studied. the critical concentration at which macroscopic phase separation occur is 1.0 mol/l. the cloud point curve is typically of (lower critical solution temperature) lcst type. the driving force responsible for shifting the lcst is hydrogen bonding and hydrophobic interaction of the macromolecules. when both the polymers have close molecular weight the polymer heteroassociation increases which in turn decreases the intramolecular interaction within pva chains. addition of hofmeister series of salts enhances the formation of complex between pva-pssna which in turn decreases the lcst of mixture of polymers. the decrease of the lcst is in the order na 2so4 < naf < nacl < naclo3 < nano3 < nabr < nascn which is opposite to classical hofmeister series. chaotropic anions favour the formation of complex more than kosmotropic anions this is because chaotropes have low surface tension values as compared to kosmotropes which lead to strengthening of hydrophobic interaction and enhances the complex formation which in turn shift the lcst toward lower temperature.