Photoswitchable ratchet surface topographies based on self-protonating spiropyran-NIPAAM hydrogels
Stumpel, Jelle E. and Ziółkowski, Bartosz and Florea, Larisa and Diamond, Dermot and Broer, Dirk J. and Schenning, Albertus P.H.J. (2014) Photoswitchable ratchet surface topographies based on self-protonating spiropyran-NIPAAM hydrogels. ACS Applied Materials and Interfaces , 6 (10). pp. 7268-7274. ISSN 1944-8244
Full text available as:
in this work, self-protonating spiropryan based poly(N-isopropylacrylamide) polymer networks are prepared. These photoresponsive hydrogel coatings can change their surface topography upon exposure with visible light in neutral environment. Photoresponsive surface constrained films have been fabricated of which the swelling behaviour 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 crosslink density thus forming a corrugated surface. Asymmetric ratchet-like photoresponsive surfaces have been prepared on pre-structured asymmetric substrates. Due to thickness variations of the surface confined hydrogel layer as 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.
Archive Staff Only: edit this record