Direct Observation of Photo Switching in Tethered Spiropyrans Using the Interfacial Force Microscope

Abstract

The interfacial force microscope has been used to establish the changes in the surface chemistry that accompany photoactivated opening and closing of rings in tethered spiropyran monolayers. Contact potential measurements show that ring opening via ultraviolet light creates a more polar surface, while exposure to visible light closes the rings and resets the surface. Normal force measurements show that open ring structures are protonated in electrolyte solutions, amplifying the switching of electrical double-layer forces.

Gestaltung der Siliciumoxidoberfläche durch selbstorganisierte Monoschichten

“…Dieses System wurde verwendet, um durch die Absorption von UV-Licht reversible ¾nderungen der Benetzbarkeit durch das Schalten zu einem polareren, zwitterionischen Merocyanin-Isomer zu bewirken. [121,122] Weitere Reaktionen auf aminoterminierten SAMs werden in den Abschnitten 3.3 und 3.4 diskutiert.…”

Tunable Wettability by Clicking Counterions Into Polyelectrolyte Brushes

“…These stimuli-induced transformations are commonly a result of changes in electrochemical potential, [3] pH, [4] solvent, [5] or irradiation. [6] In previous years, many different and innovative approaches have been explored using these stimuli as tools. Katz et al demonstrated the reversible change of wettability by using an electrochemically driven translocation of cyclophanes on molecular strings.…”

Cantilever based optical interfacial force microscope

“…Interfacial force microscopy ͑IFM͒ was developed fifteen years ago to avoid these mechanical instability problems [9][10][11] and has contributed to molecular scale understanding of various surface phenomena. IFM has been applied to diverse interfacial researches including nanotribology, [12][13][14] interfacial adhesion, 15,16 probing of interfacial water structures, 17,18 and measurements of chemical interactions. 19,20 However, the technique has not been widely used due to low sensitivity and technical complexity of the electrical-sensing method.…”