Self-recovering β-cyclodextrin gel controlled by good/poor solvent environments

A unique beta-cyclodextrin (beta-CD) gel with ordered structure was fabricated. The ordered aggregation of beta-CD was achieved by controlling the solubility of beta-CD in good/poor solvents. Physicochemical properties of the gel were systematically investigated. Mechanical properties were tested by rheological measurements, and the fibrous morphology was observed by confocal laser scanning microscopy. The anisotropic property of gel fibers was detected under polarized optical microscopy. Well-defined tetragonal and channel packed microstructures were formed in gel fibers, which revealed hollow channels of cyclodextrins. By changing physicochemical environments, macroscopic phase transitions were aroused, and self-recovering phenomena occurred when a certain amount of NaCl was added into the gel as a stimulus or the shear rate loop test was performed (thixotropy). By adjusting the concentrations of external stimuli or volume ratios of good/poor solvents, properties of the gel including mechanical strength or thermostability can be easily altered. The ordered empty channels assembled by CDs with the self-recovering properties may shed new light on this traditional host molecule.