Heat-set supramolecular polymer gel and decomposition by guests

Abstract

A degradable, heat-set supramolecular polymer network gel in N,N-dimethylformamide (DMF), based on stearic acid appended L-lysine, β-cyclodextrin and potassium carbonate, has been developed. The system exhibits gelA–sol–gelB multiple transitions. In the reversible gel system, terminally protected L-lysine are randomly organized and gelated in DMF as the temperature increases to dissolve again as the temperature decreases. In the irreversible gel system, on heating, β-cyclodextrin interacts with terminally protected L-lysine, forms a sol above T_gelA and eventually transforms to a heat-set fibrillar gelB through supramolecular polymer formation. K₂CO₃ plays a crucial role in supramolecular polymer and fibrillar gel formation. The gelA–sol–gelB transformation is accompanied by microstructural changes from nanofibers to microrods. However, the heat-set gelB is responsive to aromatic guest molecules, which decompose the supramolecular polymer and fibrillar gelB. This work may provide new avenues for delivering functional molecules and for the design of intelligent materials.