Biopolymer–surfactant interaction. I. Kinetics of binding of cetyltrimethyl ammonium bromide with carboxymethyl cellulose (Na Salt)

Abstract

AbstractThe kinetics of binding of the cationic surfactant cetyltrimethyl ammonium bromide with the Na salt of carboxymethyl cellulose was studied by the electrometric method using cetyltrimetlyl ammonium+ (CTA+) ion‐selective polyvinyl chloride membrane electrode. The binding process followed the first‐order kinetics and occurred in three stages. Its affinity increased with increasing CTA bromide concentration and decreased with ionic strength. The activation process comprised moderate E and ΔH≠ and negative ΔS≠ for all three stages with a ΔH≠ < TδS≠ trend proving it to be entropy controlled. The ΔG≠ values followed the trend ΔG < ΔG < ΔG (in accordance with k1 > k2 > k3). The enthalpies (ΔH≠) and entropies (ΔS≠) of activation followed a systematic and interdependent trend. The multiple‐stage binding kinetics is grossly comparable with the kinetics of binding of proteins to solid surfaces. © 1995 John Wiley & Sons, Inc.