Regulation of gel formation, hierarchical structures, rheological behavior, and surface wettability via the linker of molecule center on bis(cholesteric) derivatives supramolecular self-assembly systems

Abstract

A series of novel gelators (1–3) based on bis(cholesteric) derivatives with different molecular centers were designed and characterized. Their differences in molecule structures were only the linkers of molecule center. Their self-assembly process were carefully studied through different techniques including field emission scanning electron microscope (FESEM), UV–vis absorption spectra, fourier transform infrared (FTIR) spectra, rheology, X-ray diffraction (XRD) and water contact angles. Hydrophobic interaction and weak hydrogen bonding interaction may be the main driving force for gel formation. More significant, the gelation ability, self-assembly process, rheological behavior, and surface wettability of these self-assembly systems could be adjusted via the linker of molecule center. With the flexibility of the linker increasing, the gelation ability was gradually decreased. Different self-assembly structures from microrods to nanofibers were obtained in the sol-gel transition process of compounds 1–3. J-type aggregation mode was employed in gel systems 2 and 3. Interestingly, the mechanical strength of gel systems 2 and 3 was obviously stronger than that of gel system 1 in the same solvent. Xerogel film of 2 with the “lotus effect” exhibited more hydrophobicity with contact angle of 148.5° than that of xerogel films of 1 and 3. This work will bring a new method for tuning supramolecular self-assembly through the linker of molecule center.