Morphological properties of airbrush spray-deposited enzymatic cellulose thin films

Abstract

We investigate the layer formation of enzymatic cellulose by airbrush spray coating on silicon oxide surfaces. The layer structure and morphology of enzymatic cellulose films in the thickness range between 86 nm and 2.1 lm is determined as a function of the spray coating procedures. For each spray coating step, layer buildup, surface topography, crystallinity as well as the nanoscale structure are probed with atomic force microscopy and surfacesensitive X-ray scattering methods. Without intermittent drying, the film thickness saturates; with intermittent drying, a linear increase in layer thickness with the number of spray pulses is observed. A closed cellulose layer was always observed. The crystallinity remains unchanged; the nanoscale structures show three distinct sizes. Our results indicate that the smallest building blocks increasingly contribute to the morphology inside the cellulose network for thicker films, showing the importance of tailoring the cellulose nanofibrils. For a layer-bylayer coating, intermittent drying is mandatory.

Determination of the Surface Facets of Gold Nanorods in Wet‐Coated Thin Films with Grazing‐Incidence Wide Angle X‐Ray Scattering

“…Here, we use an alternative strategy to study the surface morphology and crystal structure of AuNR films through atomic force microscopy and GIWAXS that allows for the determination of surface and hidden (the intensity of the scattered wave is zero) facets. Monodisperse, single‐crystalline AuNRs were deposited on silicon substrates (<100> orientation, Si‐mat Germany) by air brush spray‐coating (cf.…”

Humidity‐Induced Nanoscale Restructuring in PEDOT:PSS and Cellulose Nanofibrils Reinforced Biobased Organic Electronics

“…Thus, this smallest structure is in the size region of the individual CNF. [ 11,24,25,33–36 ] Previously, we speculated that the largest structure might be pores within the thin film, which can be filled with polymers as shown here. From the model fits we find that the PEDOT:PSS not only affects the largest features; but also the medium sized features (CNF bundles) which increase in size from r 2,CNF = (8.5 ± 1.4) nm in CNF films to r 2,PEDOT:PSS/CNF = (11.5 ± 1.9) nm in the composite film.…”

“…X‐ray and neutron scattering techniques are suited methods to follow dynamic processes in‐situ and have successfully resolved the nanoscale re‐assembly of CNF‐based 3D objects as well as in thin films during wet and drying conditions. [ 23 ] [ 24,25 ] Grazing incidence X‐ray scattering was used to study and model the organization of PEDOT:PSS on individual CNFs. [ 26 ] In fact, GISAXS was used on samples prepared by spray deposition to study the structural changes of nanoparticles during thermal annealing.…”

Core–Shell Nanoparticle Interface and Wetting Properties

“…The cleaned substrates were then kept in MilliQ‐water until use and dried just minutes prior the spray deposition by applying a flow of nitrogen. 35,39…”

“…Spray deposition is a very versatile method for nanostructuring due to tuneable homo‐ or heterogeneous droplets or deposition on 3D shapes as in car manufacturing 36,37. Nowadays, spray deposition is also well established for thin films in combination with in situ X‐ray scattering techniques to study the nanoscale self‐assembly of particles 35,38–40. Different spray‐coating devices have been applied in both industry and academia for a long time depositing conventional colloids, however more recently focused on more advanced colloidal systems and NPs including gold,41 silica,42 Cu 2 FeSnS 4 ,43 polymeric,44 and titianium dioxide 45.…”