POLYMER SURFACTANT COMPLEXES AT THE AIR/WATER INTERFACE DETECTED BY ASIMPLE MEASURE OF SURFACE VISCOELASTICITY/

The rheology of the air/water interface of mixed polymer/surfactant sy stems has been examined by the talc particle test. Polymer/surfactant pairs studied range from strongly interacting polyelectrolytes/opposit ely charged surfactant systems, such as sodium hyaluronate/alkyltrimet hyl ammonium halides, carboxymethylcellulose/hexadecyltrimethylammomiu m chloride (HTAC), and an alternating copolymer of acrylamide and dial lyldimethylammonium chloride (Merquat-550)/sodium dodecyl sulfate (SDS ) to less strongly interacting systems of neutral polymers and charged surfactants, such as ethylhydroxyethyl cellulose/SDS or /HTAC, hydrox ypropyl cellulose/SDS, poly(N-isopropylacrylamide)/SDS and poly-(N-vin ylpyrrolidone)/SDS. Clear indications of surface viscoelasticity at th e air/water interface were obtained over a wide range of compositions for several, but not all, polymer/surfactant pairs examined. These res ults extend our previous findings (Regismond, S. T. A.; Winnik, F. M.; Goddard, E. D. Colloids Surf., A 1996, 219, 221-228.) on mixed soluti ons of SDS and a cationic derivative of hydroxyethyl cellulose (polyme r JR400). Generally, viscoelasticity provides evidence of a synergisti c adsorption of the two components. Factors influencing the developmen t of surface viscoelasticity are assessed.