Fig. 1. Chemical structures and schematic representations of BTA and BTA-PEG-BTA: (A) The BTA chemical structure has a benzene core with dodecyl hydrophobic spacers and a tail of tetra-ethylene glycol units for solubilizing in water. The BTA-PEG-BTA chemical structure is formed by two BTAs connected to poly(ethylene glycol) 20 kg mol−1 (PEG20K) using copper-azide click chemistry. (B) Schematic representations of the supramolecular networks of BTA (100 : 0) and BTA-PEG-BTA (0 : 100) hydrogelators; the benzene core and hydrophobics are shown in yellow and gray, and blue represents the tetra-ethylene glycol units. PEG20K is shown in light blue. (C) A schematic representation of BTA units stacking over each other via 3-fold hydrogen bonding interactions, resulting in micron-length long fibres. The inset images are zoomed in areas, the top shows BTA stacks in a single fibre and the bottom demonstrates the BTA fibres physical cross-links/entanglements between fibres. The image with the black arrows shows the slow rate of molecular exchange dynamics. (D) A schematic representation of BTA-PEG-BTA forming micelles due to the steric hindrance of poly(ethylene glycol). The BTA units are shown in yellow and the PEG polymer in blue. Red represents the bridges between micelles. A faster rate of molecular exchange dynamics is shown in the image with black arrows for BTA-PEG-BTA.
