Journal of polymer science part b-polymer physics vol:38 issue:21 pages:2851-2859
Small-angle X-ray scattering by means of synchrotron radiation was used to study the interaction of kappa- and iota-carrageenan of different molar mass in the presence of the gel-inducing ions, K+, with the ionic surfactants cetylpyridinium chloride (CPC) and dodecylpyridinium chloride (DPC). This interaction resulted in a more or less complete shrinking of the gel and in the formation of ordered periodic structures of the surfactant in conjunction with the carrageenan molecules. The influence of the polymer concentration for a given surfactant concentration, the content of surfactant for the same concentration of the polysaccharide, the molar mass, and the linear charge density of the polymer were all investigated. Decreasing the length of the alkyl chain of the surfactant, increasing the charge density of the polymer chain, and increasing the polymer concentration for the samples explored improved the ordering in the carrageenan-surfactant complexes. The structures of the kappa-carrageenan-CPC complexes were investigated as a function of temperature during reversible heating-cooling cycles, and it was shown that the addition of the surfactant lead to a more pronounced temperature stability of polymer network. (C) 2000 John Wiley & Sons, me.