SOLUTION PROPERTIES OF DOUBLE-TAILED CATIONIC SURFACTANTS HAVING FERROCENYL GROUPS IN THEIR HYDROPHOBIC MOIETIES

Solution properties of novel double-tailed cationic surfactants with t wo ferrocenyl groups introduced to the end of each alkyl chain ({Fc(CH 2)(n)}N-2(+)(CH3Br- (n-BFDMA; n = 5, 11)) have been investigated by li ght scattering, relative conductivity, and polarized optical microscop e measurements. The aggregation form of n-BFDMA is fairly dependent on its concentration. Scattered light intensity from a diluted (<10(-3) mol/L) 5-BFDMA solution shows a continuous increase at concentrations above 3 x 10(-5) mol/L (critical micelle concentration; cmc), suggesti ng the formation of micelles. On the other hand, the temporary decreas e of the scattered light intensity from the diluted 11-BFDMA solution was observed at concentrations between 4 x 10(-6) and 6 x 10(-6) mol/L , which is more than 1 order higher than its cmc (1 x 10(-7) mol/L). T he vesicles are found to be formed spontaneously above this concentrat ion range. Vesicle formation may be attributed to a rod-like structure of the 11-BFDMA molecule by introducing the ferrocenyl groups at the end of the hydrophobic moiety. Furthermore, observation of concentrate d (>10(-3) mol/L) solutions of 5- and 11-BFDMA by polarized optical mi croscopy shows the formation of liquid crystals dispersed in water and liquid crystals with high viscosity, respectively.