Morphology and wettability tunable organogel system based on an 1,3,4-oxadiazole derivative

A new low molecular mass organic gelator (LMOG) bearing 1,3,4-oxadiazole and azobenzene groups, namely N-(3,4,5-octanoxyphenyl)-N-4-[(4-hydroxyphenyl)azophenyl] 1,3,4-oxadiazole (AOB-t8), was designed and synthesized. The organogelator has shown great ability to gel a variety of organic solvents to form stable organogels with the critical gelation concentration as low as 5.0 × 10^-4 M and, therefore, can be considered a supergelator. It has been demonstrated that the aggregation morphology and surface wettability produced by organogels strongly depend on the nature of gelling solvents. A structure of uptwisting fibers on the substrate and superhydrophobicity were observed in the xerogel formed from 1,2-dichloroethane. The wettability of the xerogel could also be tuned by applying a sol-gel process with different solvents. Cooperation of hydrogen bonding, π-π interaction, and Van der Waals force are suggested to be the main contribution for this self-assembled structure. The unique and tunable surface properties such as superhydrophobicity distinguish the obtained organogels as a novel class of functional materials.