ETHYL(HYDROXYETHYL)CELLULOSE AND IONIC SURFACTANTS IN DILUTE-SOLUTION- CALORIMETRIC AND VISCOSITY STUDY OF THE INTERACTION WITH SDS AND SOME CATIONIC SURFACTANTS

The interaction between ethyl(hydroxyethyl)cellulose EHEC and ionic su rfactants has been studied in dilute solutions using titration microca lorimetry supplemented by viscosity measurements. Two EHEC samples of different hydrophobicity, as indicated by the differing clouding tempe ratures of 35 and 65 degrees C, were used. The surfactants studied wer e SDS, alkyltrimethylammonium halides RTAX with R equal to C-12, C-14, and C-16 and X either Br or Cl, and dodecylammonium chloride. The res ults are compared with results from measurements on dilute PEO solutio ns. The critical aggregation concentration cac, the saturation concent ration C-2, and the amount of polymer-bound surfactant were derived fr om the calorimetric titration curves. An increase in temperature from 25 to 45 degrees C had no noticeable effect on these properties, altho ugh the shape of the calorimetric titration curves changed drastically . We find that in dilute solution, the interaction of the more hydroph ilic EHEC with ionic surfactants resembles that of PEG. Both the calor imetric and viscosity results indicate that SDS interacts with EHEC th rough both the ethyl and the ethylene oxide groups while the RTAX surf actants predominately interact with the alkyl groups. While the calori metric results showed the cationic RTAX surfactants to be indifferent to PEO at ambient temperatures and to interact only weakly with the mo re hydrophilic EHEC, dodecylammonium chloride was found to interact wi th both polymers.