Noncovalent Spiropyran Coatings for Photoinduced Wettability Switching

Abstract

The noncovalent binding of spiropyran to candle-soot-covered surfaces is investigated for wettability switching using a coating procedure realized with a drop casting process of using 0.001 mol/L spiropyran in a 5 : 1 toluene-acetone mixture. Scanning electron microscopy images reveal a resulting surface with spiropyran flakes in the candle soot. A reversible switching with UV light and blue or green light is achieved, starting from an initial contact angle of 130 ∘ ± 9.68 ∘ . The highest contact angle difference is 41 ∘ and reversibility has been shown for several switching cycles. Hence, our methods provide an easy-to-use strategy to generate surfaces with switchable wettability.

Photochromic Materials by Postpolymerisation Surface Modification

“…Critical is that this outcome is achieved based upon only surface modification of the substrate and does not require dispersion into the bulk of the substrate; such photochromic behavior can be observed at typical surface loading density of ca 10 12 –10 13 molecules cm –2 . This approach compares to noncovalent and other covalent methodology suitable for the introduction of optical responsive properties in diverse applications. , …”