Salting-in and salting-out effects on cloud point of aqueous methylcellulose by addition of monomeric and polymeric sodium styrene sulfonate

Abstract

Methylcellulose attains the water-solubility by reducing the strong hydrogen-bonding. The reduction of the hydrogen bonding is achieved by partially substituting hydrophobic methoxy group for hydroxy group in cellulose. However, the substitution gives double-bladed property to the aqueous methylcellulose, namely, excessive substitution makes again methylcellulose insoluble in water. Therefore, the water-solubility of methylcellulose is strongly affected by the degree of substitution and moreover the distribution of the substituents. In this study, however, for a commercially available methylcellulose we have modified the cloud point by the addition of various organic salts. Sodium styrene sulfonate (NaSS) showed a strong salting-in effect, whereas the polymeric NaSS, i.e., sodium polystyrene sulfonate (NaPSS), showed oppositely a salting-out effect.