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An active ink composed of cellulose nanofibrils and silver nanowires was deposited on flexible and transparent polymer films using the bar coating process, achieving controlled thicknesses ranging from 200 nm up to 2 μm. For 350 nm thick coating on polyethylene terephthalate films, high transparency (75.6% transmittance) and strong reduction of bacterial growth equal to 89.3% and 100% was noted respectively against Gram-negative Escherichia Coli and Gram-positive Staphylococcus Aureus bacteria using AATCC contact active standard test. Retained antibacterial activity was found with films produced by reverse gravure roll-to-roll process, showing the promising capability of this antibacterial solution to be deployed industrially. Finally, the same ink was also deposited on polylactic acid substrate to investigate barrier properties: for 350 nm thick coating, a reduction of 49% of oxygen transmission rate (dry conditions) and 47% reduction of water vapor transmission rate was noted, proving the enhanced barrier properties of the coatings., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

TEMPO (2,2,6,6-tetramethylpiperidine-N-oxyl)-oxidized cellulose nanofibrils (T-CNF) and silver nanowires (Ag NWs) were formulated as active inks. Their rheological properties were investigated to design optimal conditions for processing by the screen-printing process, with the aim of preparing antibacterial patterns. Rheological experiments mimicking the screen-printing process were applied to different ink formulations to investigate their thixotropic and viscosity properties. The experiments conducted at 1wt% total mass content and different ratios of T-CNF/Ag NWs showed that the recovery (%), the recovery time and the viscosity are formulation dependent. A ratio 2:1 (T-CNF/Ag NWs) and total mass content of 2.5wt% were then selected to prepare an ink suitable for screen printing. Printing defects were corrected by addition of water-soluble polymer hydroxypropyl methylcellulose (HPMC). The selected formulation printed on flexible polyethylene terephthalate (PET) substrate displayed a 67.4% antibacterial activity against E. coli in a standard contact active test, with a transparency superior to 70%, proving the promising features of the developed solution for active packaging applications. [ABSTRACT FROM AUTHOR]

• Use of intense pulsed light on hydrothermally-grown ZnO nanowires. • Photonic annealed ZnO nanowires exhibited significant improvement in its crystallinity and conductivity. • Such annealing technique is suitable for use on substrates with low glass transition temperature. Hydrothermal growth of ZnO nanowires has been of great interest as it allows the use of organic substrates for flexible electronics applications. However, there are drawbacks on the growth technique as it is known to introduce defects in the nanowires. In this work, the use of intense pulsed light on hydrothermally grown ZnO nanowires on polyimide substrate was performed to enhance the physical and electronic properties of the nanomaterials. Such photonic annealing technique offers a rapid and effective improvement in material properties and importantly it is suitable for use on a wide variety of organic substrates, which are vital for flexible electronics. [ABSTRACT FROM AUTHOR]