Single Molecular Imaging of a micro-Brownian Motion and a Bond Scission of a Supramolecular Chiral π-Conjugated Polymer as a Molecular Bearing Driven by Thermal Fluctuations

The micro-Brownian motion of a single polymer chain was directly measured by high-speed (rapid-scan) AFM on a mica substrate under an aqueous solution at room temperature. The diffusion constant was 1.3×10−14 m2/s, which is a basic property of a molecular bearing at a solid–liquid interface. The molecule was a micrometer-long supramolecular chain in which π-conjugated polyrotaxane was coupled by a π–π interaction. Bond scission of this supramolecular chain was directly observed, and the dynamic folding behavior of a single polymer chain was also imaged.