Low-temperature atomic layer deposition of SiO ₂ /Al ₂ O ₃ multilayer structures constructed on self-standing films of cellulose nanofibrils

Abstract

In this paper, we have optimized a low-temperature atomic layer deposition (ALD) of SiO 2 using AP-LTO® 330 and ozone (O 3 ) as precursors, and demonstrated its suitability to surface-modify temperature-sensitive bio-based films of cellulose nanofibrils (CNFs). The lowest temperature for the thermal ALD process was 80°C when the silicon precursor residence time was increased by the stop-flow mode. The SiO 2 film deposition rate was dependent on the temperature varying within 1.5–2.2 Å cycle −1 in the temperature range of 80–350°C, respectively. The low-temperature SiO 2 process that resulted was combined with the conventional trimethyl aluminium + H 2 O process in order to prepare thin multilayer nanolaminates on self-standing CNF films. One to six stacks of SiO 2 /Al 2 O 3 were deposited on the CNF films, with individual layer thicknesses of 3.7 nm and 2.6 nm, respectively, combined with a 5 nm protective SiO 2 layer as the top layer. The performance of the multilayer hybrid nanolaminate structures was evaluated with respect to the oxygen and water vapour transmission rates. Six stacks of SiO 2 /Al 2 O with a total thickness of approximately 35 nm efficiently prevented oxygen and water molecules from interacting with the CNF film. The oxygen transmission rates analysed at 80% RH decreased from the value for plain CNF film of 130 ml m −2 d −1 to 0.15 ml m −2 d −1 , whereas the water transmission rates lowered from 630 ± 50 g m −2 d −1 down to 90 ± 40 g m −2 d −1 . This article is part of a discussion meeting issue ‘New horizons for cellulose nanotechnology’.

Production and Surface Modification of Cellulose Bioproducts

“…The ALD technique is widely used in many important industrial applications (e.g., protective coatings, microelectronics, photovoltaics, and solid oxide fuel cells) [ 86 ]. Studies have shown that ALD can be successfully employed to impart functional coatings of metal oxides and metal nitrides onto different types of cellulose based substrates such as cotton fibers [ 87 , 88 ], viscose fibers [ 88 ], and nanocellulose films [ 89 ].…”

Cellulose-inorganic hybrids of strongly reduced thermal conductivity

“…Overall, the incorporation of nanocellulose in an inorganic structure for efficient manipulation of the thermal properties in the final hybrid composite, has been analytically described (Nie et al 2020a, b;Zhang et al 2020Zhang et al , 2019. Previously, we have optimized the low temperature ALD multilayer deposition process on nanocellulose for the control over oxygen and water vapor transmission rates (Putkonen et al 2017). The employment of nanocellulose for fabrication of energy-related hybrid inorganic-organic systems, however, still exhibits plenty of space to be explored.…”

Depósito por aspersión de una capa protectora de SiO2–PMMA sobre acero AISI 1036 con propiedades de barrera a contaminantes atmosféricos

“…Los compuestos químicos liberados a la atmósfera se disocian formando iones, que al interactuar con la superficie del acero alcanzan potenciales de oxidación de 0.68V y 0.51V para Cl -, SO2 respectivamente [4,5]. Los mecanismos de protección de este tipo de metales se han usado desde el siglo XIX con protecciones del tipo físico en forma de barrera [6][7][8] y químico cuando el otro material se sacrifica para evitar el deterioro de la estructura [9][10][11]. Sin embargo, con los altos índices de contaminación y el incremento de la emisión de los gases de efecto invernadero, la tendencia en innovaciones a proteger estos metales se sigue incrementando.…”