Stimuli-Responsive Designer Supramolecular Polymer Gel

Abstract

This paper reports a stimuli-responsive designer supramolecular polymer gel in dimethylsulphoxide (DMSO)/water (1:2) based on a dipeptide amphiphile and β-cyclodextrin (β-CD) The dipeptide amphiphile contains caproic acid at the N terminus and methyl ester at the C terminus. From X-ray single crystal diffraction, the amphiphile adopts a kink-like conformation. The amphiphile self-assembled to form a parallel sheet-like structure stabilized by multiple intermolecular hydrogen bonds. Moreover, the parallel sheet-like structure is also stabilized by edge-to-edge π–π stacking interactions. In higher-order packing, it forms a corrugated sheet-like structure stabilized by hydrophobic interactions. The dipeptide amphiphile interacts with β-cyclodextrin and forms gel through supramolecular polymer formation in (DMSO)/water (1:2) by a simple heating-cooling cycle. The sol-to-gel transformation is because of a host–guest complex between compound 1 and β-CD and the formation of supramolecular polymer accompanied by microstructure changes from nanofibers to microrods. The gel is temperature responsive with a Tgel of 70 °C. The supramolecular polymer gel is also responsive to stimuli such aspicric acid and HCl. The extensive spectroscopic studies show that the aromatic hydrophobic side chain of compound 1 forms a host–guest complex with β-CD. These results will be helpful for the design of advanced programable eco-friendly functional materials.

Research on the Production of Pigments Based on Composite Pellets in the Recycling of Industrial Waste

“…When studying the process of roasting chromite and internal overburden rock containing pellets, we took averaged samples and carried out numerous experiments to determine the optimal values. Based on the experiments performed, the optimal values do not exceed the permissible error in the range of 0.1-0.2% [49,50].…”

Tools to enable the study and translation of supramolecular amphiphiles

“…Haldar and co-workers utilised SC-XRD in their study characterising acid and thermal responsive supramolecular polymer gels. 76 The authors synthesised 7 (Fig. 7A), designed to be complimentary to the toroidal structure of cyclodextrin, resulting in the formation of a supramolecular polymer which, upon heating and cooling, formed a gel in a DMSO : H 2 O (1 : 2) solution.…”