BIOPOLYMER SURFACTANT INTERACTION .1. KINETICS OF BINDING OF CETYLTRIMETHYL AMMONIUM BROMIDE WITH CARBOXYMETHYL CELLULOSE (NA SALT)

The kinetics of binding of the cationic surfactant cetyltrimethyl ammo nium bromide with the Na salt of carboxymethyl cellulose was studied b y the electrometric method using cetyltrimethyl ammonium(+) (CTA(+)) i on-selective polyvinyl chloride membrane electrode. The binding proces s followed the first-order kinetics and occurred in three stages. Its affinity increased with increasing CTA bromide concentration and decre ased with ionic strength. The activation process comprised moderate E( a)(not equal) and Delta H-not equal and negative Delta S-not equal for all three stages with a Delta H-not equal < T Delta S-not equal trend proving it to be entropy controlled. The Delta G(not equal) values fo llowed the trend Delta G(1)(not equal) < Delta G(2)(not equal) < Delta G(3)(not equal) (in accordance with k(1) > k(2) > k(3)). The enthalpi es (Delta H-not equal) and entropies (Delta S-not equal) of activation followed a systematic and interdependent trend. The multiple-stage bi nding kinetics is grossly comparable with the kinetics of binding of p roteins to solid surfaces. (C) 1995 John Wiley & Sons, Inc.