부산대학교 도서관

We report here the gelation behaviorof two novel l-cysteine-basedamphiphiles bearing a poly(ethylene glycol) tail. The amphiphileswere found to form transparent organogels in both apolar and aproticpolar solvents at reasonably low concentrations. In chloroform, dichloromethane,and benzene solvents, the organogels are formed at room temperaturewithout the requirement of heating–cooling cycle due to stronghydrogen-bonding interaction between gelator molecules. The swellingkinetics, however, becomes faster on heating. Unlike most organogelsof low-molecular-mass gelators, these organogels do not exhibit agel-to-sol transition on heating but instead become rigid when heated.Surprisingly, in polar solvents, the gelation required a heating–coolingcycle, and the sol-to-gel transition was found to be reversible. Thegelation abilities of the amphiphiles were correlated with the hydrogen-bondingparameters of the solvents. Intermolecular H-bonding interaction wasfound to be the major driving force for the organogelation. The morphologyof the organogels was investigated by the use of optical as well aselectron microscopy and was found to be dependent on the nature ofsolvent. The mechanical strengths of the organogels were studied byrheological measurements. [ABSTRACT FROM AUTHOR]