Kallweit, C., Bremer, M., Smazna, D., Karrock, T., Adelung, Rainer and Gerken, M. (2017) Photoresponsive hierarchical ZnO-PDMS surfaces with azobenzene-polydopamine coated nanoparticles for reversible wettability tuning. Vacuum, 146 . pp. 386-395. DOI 10.1016/j.vacuum.2017.03.023.

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Abstract

Azobenzene-bearing surfaces are promising for light-controlled wettability switching in microfluidic systems. We investigate the wettability and stability of flat glass, flat polydimethylsiloxane (PDMS) and hierarchical ZnO-PDMS surfaces functionalized with azobenzene bearing polydopamine coated nanoparticles (Azo-PDA-NP). We analyse the stability of the contact-angle switching when using new droplet locations for each measurement and for using the same droplet location with compressed-nitrogen drying between measurements. For flat glass surfaces we observed a wettability change of 15° and 60° for spin-coating and drop-casting deposition of the Azo-PDA-NP, respectively. For the PDMS samples, 60° contact-angle change are obtained, but these surfaces show degradation for repeated switching cycles. In contrast the hierarchical ZnO-PDMS surfaces exhibit a wettability switch of 50° and no degradation for five switching cycles at the same droplet location. We captured water drops during ultra-violet (UV) irradiation on video and obtained a one-sided flowing motion with a speed of 1.9 μm/s. Contact-angle hysteresis measurements show that the minimum criterion for droplet movement is fulfilled for the Azo-PDA-NP functionalized hierarchical ZnO-PDMS surfaces.

Document Type:	Article
Keywords:	Azobenzene Hierarchical surface Photo responsivity Smart surface Wettability change
Research affiliation:	Kiel University > Kiel Marine Science OceanRep > The Future Ocean - Cluster of Excellence
Refereed:	Yes
Open Access Journal?:	No
Publisher:	Elsevier
Projects:	Future Ocean
Date Deposited:	12 Dec 2017 13:30
Last Modified:	29 Apr 2019 15:14
URI:	https://oceanrep.geomar.de/id/eprint/40544

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