X-ray structural studies of induced lyotropic cholesteric phases in the quaternary system hexadecyl dimethylethyl ammonium bromide/water/n-decanol/taurocholic acid

In the quaternary system hexadecyl dimethylethyl ammonium bromide (C(16)Me( 2)EABr)/water/n-decanol/taurocholic acid, X-ray structural measurements wer e carried out to investigate the formation of the lyotropic cholesteric dis k-like phase Ch(D) in a matrix of the lyotropic nematic disk-like phase No induced by the addition of taurocholic acid. The structural properties of t hese phases are described by structural parameters. The effect of the tauro cholic acid concentration on the structure formation of the Ch(D) phase cor relates with a decrease in the helix length. This decrease is accompanied b y a reduction in micelle anisotropy. The change in the micellar geometry co rrelates with a reduction in micellar volume and aggregation number in the Cho phase. The matrix effect of the N-D phase on the formation and properti es of the Cho phase correlates with a decrease in micellar anisotropy. The micellar volumes and average aggregation numbers in the ChD phase exceed th ose in the ND phase. The structural parameters of the micelles in the Ch(D) phase are clearly dependent on the C(16)Me(2)EABr concentration.