Organogelation by 4-(N-tetradecanoyl)aminohydroxybutyric acids: effect of hydrogen-bonding group in the amphiphile head.

The major driving force for organogelation is known to be hydrogen bonding for gelators containing functional groups capable of forming hydrogen bond(s). In order to examine this, we have investigated the gelation behavior of two 4-(N-tetradecanoyl)aminohydroxybutanoic acid amphiphiles in a series of organic solvents and compared with those of the corresponding unsubstituted amphiphile 4-(N-tetradecanoyl)aminobutanoic acid (C14-ABA). The gelation ability of the nonhydroxyl amphiphile C14-ABA was found to be better than the hydroxyl group substituted amphiphiles. An attempt was also made to correlate gelation abilities of the amphiphiles with the solvent polarity parameters. The driving force for the gelation was studied by Fourier transform infrared and (1)H NMR spectroscopy. The organogels were characterized by electron microscopy and XRD. The thermal stability of the gels was investigated by measuring the sol-to-gel transition temperature. Rheological measurements were performed in order to determine the mechanical stability of the organogels. The gelation ability and thermal and mechanical stability of the organogels were correlated with the intermolecular hydrogen-bonding interactions between amphiphile head groups.