Preparation And Performances Of Organogels Based On Some Functional Amphiphilic Molecules

It is well known that organogels are one class of important soft materials. Althoughgels are widely found in polymer systems, in recent years, physical gelation of organicsolvents by low molecular-mass organic gelators (LMOGs) has become one of the hotareas in the soft matter research. The gels based on LMOGs are usually considered assupramolecular gels, in which the gelator molecules self-assemble into three-dimensionalnetworks in which the solvent is trapped via various non-covalent interactions, such ashydrogen bonding, π-π stacking, van der Waals interaction, dipole-dipole interaction,coordination, solvophobic interaction, and host-guest interaction.Graphene oxide (GO), a single sheet of graphite oxide bearing oxygen functionalgroups on their basal planes and edges has become more effective as a nano-materials dueto its superior structural and thermal properties compared to other conventionalnano-materials. It can be prepared from natural graphite which is an easily available lowcost material and therefore it is preferred over other expensive fillers like carbon nanotube(CNT).In this paper, new azobenzene imide derivatives with different substituent groupswere designed and synthesized. Their gelation behaviors in21solvents were tested asnovel low-molecular-mass organic gelators. It was shown that the alkyl substituent chainsand head groups of azobenzene residues in gelators played a crucial role in the gelationbehavior of all compounds in various organic solvents. More alkyl chains in molecularskeletons in present gelators are favorable for the gelation of organic solvents. Scanningelectron microscopy and atomic force microscopy observations revealed that the gelatormolecules self-assemble into different aggregates, from wrinkle, lamella, and belt to fiberwith the change of solvents. Spectral studies indicated that there existed H-bondformations between amide groups.Next, a series of cationic amphiphilic surfactant were prepared and then mixed withGO. The gelation behaviors of cationic amphiphile-GO composites were tested indifferent organic solvents. With the purpose of obtaining a visual insight into the gel microstructures, the typical nanostructures of GO and the xerogels were studied usingscanning electron microscope (SEM). From the SEM pictures of GO, we can tell that GOhas a smooth surface with large surface area. The GO can be considered as a single sheetbecause of d=1.03nm which is very close to the theoretical value (1nm). FT-IR Figuresindicated that there are a large number of oxygen functional groups on their basal planesand edges which can form hydrogen bonds in composite gels. SEM and AFMobservations revealed that the gelator molecules self-assemble into different aggregates,from wrinkle to lamella with the change of solvents which is consistent with the results ofX-ray diffraction (XRD). Hydrogen bonding, π-π interactions and van der Waals forcesare the main driving force in cationic amphiphiles-GO composite gels.