Interaction of hydroxypropylcellulose with hexadecylbenzyldimethylammonium chloride in the absence and presence of hydrophobic salts

The interaction between nonionic semi-flexible polymer. hydroxypropylcellulose (HPC) and cationic surfactant hexadecylbenzyldimethylammonium chloride (C(16)BzCl) has been studied in aqueous sodium chloride (NaCl), sodium hexanoate (NaHx) and propylammonium chloride (PrACl) solutions employing conductivity, viscosity and cloud point measurements. The salts selected allowed us to investigate the effect of hydrophobic co- and counter-ions compared with simple ions upon polymer-surfactant interaction. Cloud point and viscometric results indicate interaction between C(16)BzCl and HPC although not reflected from condutometric data. Addition of different levels of salts to the polymer-surfactant system reveal that the charge compensation of micelles bound to the polymer chains is less in the presence of NaHx than in NaCl or PrACl, both showing similar effect. Also the effect of increase in surfactant concentration at a particular polymer plus additive concentration is equivalent to the increase in hydrophobic modification of the polymer as reflected in cloud point and viscosity decrease. (C) 2009 Elsevier B.V. All rights reserved.