Phys.com November 30, 2021
An international team of researchers (Japan, Switzerland, UK) built the supramolecular polymer from monomers that formed six-membered rosettes stacked on top of one another to give an infinitely long chain. An intrinsic curvature generated along the stacked rosettes caused the nanofibers to twist up and fold into a helical structure. The folding could be removed by triggering a “light switch”. UV-light irradiation caused the monomer to bend, forming a kink in the molecule, reducing the rotation of the rosette, and unfolding the helical structure. A second switch which works using temperature prevented the entire polymer from unfolding uniformly. Heating then gave rise to a state in which the polymer reacted to the UV irradiation by unfolding in a non-uniform, cooperative way. Upon prolonged irradiation and keeping the polymer warm, the helical blocks became shorter until the entire structure was reduced to an unordered cluster. According to the researchers the results obtained from computer modeling illustrate how isomerization occurring in ordered domains in the assemblies can be at the origin for the separation of a supramolecular polymer into folded and unfolded regions. The findings may open new possibilities for nanofabrication of functional soft materials…read more. Open Access TECHNICAL ARTICLE
Helically folded supramolecular polymers with a high internal rigidity undergo non-uniform unfolding upon UV-irradiation… Credit: Angewandte Chemie International Edition, 08 October 2021Â