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.
