Micro-patterns on nanocellulose films and paper by photo-induced thiol–yne click coupling: a facile method toward wetting with spatial resolution
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We report a facile approach to tailor the wettability of ligno-cellulosic substrates via photo-induced thiol–yne click coupling. First, cellulosic surfaces were functionalized with 4-pentynoic acid to introduce terminal alkyne moieties for the subsequent photo-induced coupling in heterogeneous phase. Next, the (primed) surfaces were reacted with various thiol-containing molecules to systematically tailor the surface energy. Finally, the method was applied to nanocellulose films and paper to develop micro-patterned surfaces via UV lithography, endowing the substrates with thin hydrophilic channels (~ 250 μm thickness) and hydrophobic boundaries between neighboring water droplets, as small as 100 μm in width. Overall, we propose thiol-click as a facile method toward spatially-resolved wetting that enables paper-based electronics in smart labels and point-of-care bioplatforms.
KeywordsNanocellulose Surface functionalization Photo-induced thiol–yne reaction Micro-patterns
This research was financially supported by the Academy of Finland through Centers of Excellence Program (2014–2019), ERC Starting Grant (ID: 337077-DropCellArray) and the Helmholtz Association’s Initiative and Networking Fund (Grant no. VH-NG-621). The authors acknowledge Dr. Maria Soledad Peresin (VTT Technical Research Centre of Finland Ltd, Finland) for providing the CNF films. J.G. acknowledges travel support from Aalto University Foundation and Paper Engineers’ Association. This work made use of the Aalto University Nanomicroscopy Center (Aalto-NMC) premises.
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