Molecular design of photoswitchable surfaces with controllable wettability


Journal of Materials Chemistry, vol.21, no.9, pp.3189-3196, 2011 (Peer-Reviewed Journal) identifier identifier

  • Publication Type: Article / Article
  • Volume: 21 Issue: 9
  • Publication Date: 2011
  • Doi Number: 10.1039/c0jm03528a
  • Journal Name: Journal of Materials Chemistry
  • Journal Indexes: Science Citation Index Expanded, Scopus
  • Page Numbers: pp.3189-3196


In this work, we developed a photocontrollable substrate which was prepared using an azobenzene-containing self-assembled monolayer (SAM) on the silicon surface via the chemisorption of 3-glycidoxypropyltrimethoxysilane (GPTS) and 4-(4′-aminophenylazo) benzoic acid (APABA). The prepared surfaces were chemically characterized by X-ray photoelectron spectroscopy (XPS). The reversible photoswitching performance of APABA molecules were investigated by UV spectroscopy in dimethylsulfoxide (DMSO) solution. To understand and control this reversible photoswitchable mechanism and wettability properties, contact angle measurements were performed by using a variety of liquids after UV and visible light irradiation. These contact angle results are used to approximate the components of the APABA-modified surface energy under UV and visible light using the Lifshitz-van der Waals/acid-base approach. The total surface energy (γs) after visible light irradiation (for trans formation) was calculated to be 37.28 mJ m-2, whereas the value after UV light exposure (for cis formation) was also calculated to be 36.95 mJ m-2. All the results demonstrate the great potential to control molecular events within and on the surfaces of molecular constructs using light. © The Royal Society of Chemistry 2011.