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Photoresponsive Sponge‐Like Coating for On‐Demand Liquid Release
Author(s) -
Gelebart Anne Helene,
Liu Danqing,
Mulder Dirk J.,
Leunissen Kevin H. J.,
van Gerven Jop,
Schenning Albert P. H. J.,
Broer Dirk J.
Publication year - 2018
Publication title -
advanced functional materials
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 6.069
H-Index - 322
eISSN - 1616-3028
pISSN - 1616-301X
DOI - 10.1002/adfm.201705942
Subject(s) - materials science , coating , liquid crystal , azobenzene , homeotropic alignment , chemical engineering , polymerization , composite material , polymer , optoelectronics , engineering
Many publications report on stimuli responsive coatings, but only a few on the controlled release of species in order to change the coating surface properties. A sponge‐like coating that is able to release and absorb a liquid upon exposure to light has been developed. The morphology of the porous coating is controlled by the smectic liquid crystal properties of the monomer mixture prior to its polymerization, and homeotropic order is found to give the largest contraction. The fast release of the liquid can be induced by a macroscopic contraction of the coating caused by a trans to cis conversion of a copolymerized azobenzene moiety. The liquid secretion can be localized by local light exposure or by creating a surface relief. The uptake of liquid proceeds by stimulating the back reaction of the azo compound by exposure at higher wavelength or by thermal relaxation. The surface forces of the sponge‐like coating in contact with an opposing surface can be controlled by light‐induced capillary bridging revealing that the controlled release of liquid gives access to tunable adhesion.