SANS study of surfactant ordering in kappa-carrageenan/cetylpyridinium chloride complexes

Small-angle neutron scattering using contrast variation by H2O/D2O has been applied for the structural investigation of kappa -carrageenan/cetylpyridi nium chloride (CPC) complexes. interaction of kappa -carrageenan with an io nic surfactant involves self-assembly of the surfactant molecules in conjun ction with the carrageenan molecules and the formation of an ordered struct ure. Contrast matching conditions for the polysaccharide (70% H2O/30% D2O) allowed to obtain the small-angle scattering pattern from the surfactant pa rt of the complexes. The SANS curves reveal that the observed scattering he terogeneities represent regions with sharp phase boundaries. From the Guini er part of the scattering curves, the size of these regions is determined. The obtained values are in good agreement with the structural characteristi cs of the kappa -carrageenan/CPC complexes determined independently by SAXS and SANS from the position and the half-width of the Braggs peaks of the s cattering patterns. (C) 2001 Elsevier Science Ltd. All rights reserved.