Switching adhesion and friction by light using photosensitive guest-host interactions.

Area of Science:

• Supramolecular Chemistry
• Surface Science
• Nanotechnology

Background:

• Friction and adhesion are critical surface properties.
• Controlling these properties with external stimuli is a significant challenge.
• Cyclodextrins offer unique host-guest complexation capabilities.

Purpose of the Study:

• To investigate light-switchable friction and adhesion between functionalized surfaces.
• To explore the use of azobenzene molecules as photo-responsive linkers.
• To quantify single-molecule interaction forces in a light-controlled system.

Main Methods:

• Atomic Force Microscopy (AFM) with β-cyclodextrin functionalized tips.
• Utilizing ditopic azobenzene guest molecules for host-guest complexation.
• Measuring single-molecule rupture forces under varying light conditions.

Main Results:

• Reversible switching of friction and adhesion between surfaces was demonstrated.
• Light stimuli effectively modulated the interaction forces.
• The rupture force of individual β-cyclodextrin-azobenzene complexes was measured at 61 ± 10 pN.

Conclusions:

• External light stimuli can reversibly control friction and adhesion.
• Azobenzene-mediated cyclodextrin complexation provides a mechanism for light-switchable surface interactions.
• This work offers a foundation for light-responsive nanomaterials and devices.