Fluoresence probe techniques have been employed to monitor interactions of sodium carboxymethylamylose (NaCMA) with cationic and anionic surfactants in aqueous solution in both the absence and the presence of added salt. The changes of the 11/13 ratio of the fluorescence of pyrene in NaCMA solution were measured as a function of hexadecyltrimethylammonium chloride (HTAC) and sodium dodecyl sulphate (SDS) concentration. In the absence of added salt, mixed micelle formation of NaCMA with both HTAC and SDS was observed with an apparent critical micelle concentration (CMC) of 1 ? 10 -4 and 3 x 10- 3 M respectively. These are the first observations of mixed micelle formation between an anionic surfactant and an anionic polyelectrolyte. The average aggregation numbers of the mixed micelles were measured by the analysis of the fluoresence decay curve of the micelle-solubilized pyrene to be smaller than that for the micelles in the absence of NaCMA. In the presence of 2% NaCI the apparent CMC values of the surfactants are greater than those in the absence of NaCMA, suggesting that NaCMA forms inclusion complexes with both HTAC and SDS. The association constant of NaCMA with HTAC is 4.1 ? 104 M -1, and the maximum amount of bound HTAC per anhydroglucose residue is 0.014. This result is consistent with the model of interrupted 6-helix conformation of NaCMA.
Посилання на статтю:
Interaction of sodium carboxymethylamylose with aqueous surfactants in both the presence and the absence of added salt: mixed micelles and inclusion complexes / Zhen Zhen and Chen-Ho Tung // Polymer. – 1992. – Vol 33. – P. 812-816.