Description:
<jats:p>
In this paper, we have optimized a low-temperature atomic layer deposition (ALD) of SiO
<jats:sub>2</jats:sub>
using AP-LTO® 330 and ozone (O
<jats:sub>3</jats:sub>
) 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
<jats:sub>2</jats:sub>
film deposition rate was dependent on the temperature varying within 1.5–2.2 Å cycle
<jats:sup>−1</jats:sup>
in the temperature range of 80–350°C, respectively. The low-temperature SiO
<jats:sub>2</jats:sub>
process that resulted was combined with the conventional trimethyl aluminium + H
<jats:sub>2</jats:sub>
O process in order to prepare thin multilayer nanolaminates on self-standing CNF films. One to six stacks of SiO
<jats:sub>2</jats:sub>
/Al
<jats:sub>2</jats:sub>
O
<jats:sub>3</jats:sub>
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
<jats:sub>2</jats:sub>
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
<jats:sub>2</jats:sub>
/Al
<jats:sub>2</jats:sub>
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
<jats:sup>−2</jats:sup>
d
<jats:sup>−1</jats:sup>
to 0.15 ml m
<jats:sup>−2</jats:sup>
d
<jats:sup>−1</jats:sup>
, whereas the water transmission rates lowered from 630 ± 50 g m
<jats:sup>−2</jats:sup>
d
<jats:sup>−1</jats:sup>
down to 90 ± 40 g m
<jats:sup>−2</jats:sup>
d
<jats:sup>−1</jats:sup>
.
</jats:p>
<jats:p>This article is part of a discussion meeting issue ‘New horizons for cellulose nanotechnology’.</jats:p>