Iso- and Anisotropic Etching of Micro Nanofibrillated Cellulose Films by Sequential Oxygen and Nitrogen Gas Plasma Exposure for Tunable Wettability on Crystalline and Amorphous Regions

Abstract

The surface of cellulose films, obtained from micro nanofibrillated cellulose produced with different enzymatic pretreatment digestion times of refined pulp, was exposed to gas plasma, resulting in a range of surface chemical and morphological changes affecting the mechanical and surface interactional properties. The action of separate and dual exposure to oxygen and nitrogen cold dielectric barrier discharge plasma was studied with respect to the generation of roughness (confocal laser and atomic force microscopy), nanostructural and chemical changes on the cellulose film surface, and their combined effect on wettability. Elemental analysis showed that with longer enzymatic pretreatment time the wetting response was sensitive to the chemical and morphological changes induced by both plasma gases, but distinctly oxygen plasma was seen to induce much greater morphological change while nitrogen plasma contributed more to chemical modification of the film surface. In this novel study, it is shown that exposure to oxygen plasma, subsequently followed by exposure to nitrogen plasma, leads first to an increase in wetting, and second to more hydrophobic behaviour, thus improving, for example, suitability for printing using polar functional inks or providing film barrier properties, respectively.

Solution casting of cellulose acetate films: influence of surface substrate and humidity on wettability, morphology and optical properties

“…11, for films cast on PTFE, the contact angle of patterned down side is 32% higher than that of the upper side. It is usually admitted that rough surfaces tend to lower the wettability (Hansson et al 2011;Dimic-Misic et al 2021). In the present work, the mere change in roughness is not the main reason for a change in wettability, but rather the patterned surface with regular periodic morphology, causes the higher contact angle.…”

Active Cellulose Acetate/Chitosan Composite Films Prepared Using Solution Blow Spinning: Structure and Electrokinetic Properties

“…The porosity of the produced samples was determined gravimetrically by dividing the density of the sample ( ρ s ) with the theoretical density ( ρ t ) of the non-porous composite [ 47 ], according to Equation (1): …”