Halloysite Applied In The Research On Self-assembling Of Gelator And Enhancement Of Supramolecular Gel

Halloysite is a natural multi-walled nanotubes having a large hollow cavity that is a good space to conduct molecular confined study, and as a kind of inorganic clay mineral, halloysite can be used on the study of the molecular gel strength through appropriate modified.In this work, we choice DBS and cyclohexanone as gelator and solvent respectively, and prepare the DBS/cyclohexanone gel samples of the confined space within empty cavity of halloysite by mixed acid treatment, and compare the DSC and XRD data of this samples with that in bulk space. The results indicate that the gel-sol phase transition temperature of this samples prepared within confined space rose to130.94℃in contrast to97.35℃in bulk space. Lowest-energy molecular conformations of DBS were obtained by simulation software Spartan’02, UV spectrum and FT-IR data proved that the main driving forces for DBS to form fibrils are π-π stacking of the benzene ring and hydrogen bonding. On this basis, we determine the position of a key by combining with large amounts of data, and thereby speculate the different manner for self-assembling of gelator DBS in body and confined space, and analysis the reason for the change on phase transition temperature.We dispersed certain amount KH550modified halloysite (m-HNTs) in1,2-propanediol or iso-butanol hot solution containing DBS by stirring and ultrasonic, and prepared a uniformly dispersed nanocomposite organic gel with good stability. At the same time, we prepared nanocomposite hydrogel by mixing the unmodified halloysite (HNTs) and sodium deoxycholate (NaDC) and solid NaCl at pH=7buffer solution. The compression test and rheology results of nanocomposite gel show that the strength of composite gel increase first and then decrease along with the increase on the added amount of m-HNTs (or HNTs). For instance, in DBS/1,2-propylene glycol/m-HNTs organic gel systems, the strength of the gel that m-HNTs were added in an amount of5% is greater than that with the dosage of10%. Based on different structural stages of the formation process of gel, we speculate that when the added amount of the halloysite is appropriate, it mainly as inorganic matrix disperses uniformly in the three-dimensional network of gel. When added excessively, it will reduce the probability of that DBS molecular in unit space aggregate and assemble to form fibrils, and thereby reduce the macro strength of the gel to a certain extent.