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

Abstract

A unique b-cyclodextrin (b-CD) gel with ordered structure was fabricated. The ordered aggregation of b-CD was achieved by controlling the solubility of b-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.

Superstructure Formation and Topological Evolution Achieved by Self-Organization of a Highly Adaptive Dynamer

“…Highly cross-linked fibers could facilitate the formation of ultrastable and robust supramolecular organogels, which were further investigated by rheological studies. The gels showed a linear viscoelastic region (Figure a as well as Figures S9 and S10 in the SI) over a wide applied stress region from 0.01 Pa to yield stress points, after which the gels collapse into the liquid, exhibiting non-Newtonian fluid characteristics . According to the dynamic frequency sweep (Figure b and Figure S9 in the SI) in the linear viscoelastic region (τ = 1.0 Pa), the gels behaved as a solid.…”

“…The gels showed a linear viscoelastic region (Figure 3a as well as Figures S9 and S10 in the SI) over a wide applied stress region from 0.01 Pa to yield stress points, after which the gels collapse into the liquid, exhibiting non-Newtonian fluid characteristics. 40 According to the dynamic frequency sweep (Figure 3b and Figure S9 in the SI) in the linear viscoelastic region (τ = 1.0 Pa), the gels behaved as a solid. At the applied frequency (f = 0.1−100 Hz), values of the storage modulus (G′) were nearly 1 order of magnitude higher than that of the loss modulus (G″), and both G′ and G″ were invariant with frequency until a certain yield value.…”

Melamine as an Effective Supramolecular Modifier and Stabilizer in a Nanotube‐Constituted Supergel

“…However, when the amplitude returns, the gel only recovers 10 % of its mechanical strength. This remarkable hysteresis13d may be caused by a time lag, which commonly remains in thixotropic or strength‐recovery systems. On imposing high applied stress or shear rate on a gel, its three‐dimensional entangled networks are broken into shorter fragments, among which the interfiber interaction is very weak.…”

pH-Responsive Dipeptide-Based Dynamic Covalent Chemistry Systems Whose Products and Self-Assemblies Depend on the Structure of Isomeric Aromatic Dialdehydes

“…To further explore the microstructures of molecular packing, we employed SAXS, which was often used to identify the structures of soft materials. , The scattering data fitted best to the flexible cylinder model, implying that metastructures or fabric structures existed in the OPGG gel (Figure c). The obvious peak was obtained with the d spacing of 1.73 nm, which is longer than the length of an OPGG molecule (ca.…”