Photoswitchable ratchet surface topographies based on self-protonating spiropyran-NIPAAM hydrogels

ACS Appl Mater Interfaces. 2014 May 28;6(10):7268-74. doi: 10.1021/am500542f. Epub 2014 May 16.

Abstract

In this work, self-protonating spiropyran-based poly(N-isopropylacrylamide) polymer networks are prepared. These photoresponsive hydrogel coatings can change their surface topography upon exposure with visible light in a neutral environment. Photoresponsive surface-constrained films have been fabricated for which the swelling behavior can be controlled in a reversible manner. In a first step, symmetrical switchable surface topologies with varying cross-link density are obtained by polymerization-induced diffusion. Under light exposure, the areas with low cross-link density swell more than the areas with high cross-link density, thus forming a corrugated surface. Asymmetric ratchet-like photoresponsive surfaces have been prepared on prestructured asymmetric substrates. As a result of thickness variation of the surface-confined hydrogel layer, an asymmetric swelling behavior is obtained. Depending on the cross-link density of the hydrogel, it is possible to switch between a ratchet and flat surface topography or even an inverse ratchet surface by light.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acrylic Resins / chemistry*
  • Benzopyrans / chemistry*
  • Diffusion
  • Hydrogels / chemistry*
  • Indoles / chemistry*
  • Isomerism
  • Light
  • Nitro Compounds / chemistry*
  • Polymerization
  • Surface Properties

Substances

  • Acrylic Resins
  • Benzopyrans
  • Hydrogels
  • Indoles
  • Nitro Compounds
  • merocyanine
  • spiropyran
  • poly-N-isopropylacrylamide