Abstract
Water interactions and accessibility of the nanoscale components of plant cell walls influence their properties and processability in relation to many applications. We investigated the water-accessibility of nanoscale pores within the fibrillar structures of unmodified Norway spruce cell walls by small-angle neutron scattering (SANS) and Fourier-transform infra-red (FTIR) spectroscopy. The different sensitivity of SANS to hydrogenated (hbox {H}_2hbox {O}) and deuterated water (hbox {D}_2hbox {O}) was utilized to follow the exchange kinetics of water among cellulose microfibrils. FTIR spectroscopy was used to study the time-dependent re-exchange of OD groups to OH in wood samples transferred from liquid hbox {D}_2hbox {O} to hbox {H}_2hbox {O}. In addition, the effects of drying on the nanoscale structure and its water-accessibility were addressed by comparing SANS results and the kinetics of water exchange between never-dried and dried/rewetted wood samples. The results of the kinetic analyses allowed to identify two processes with different timescales. The diffusion-driven exchange of water in the spaces between microfibrils, which was observed with both SANS and FTIR, takes place within minutes and rather homogeneously. The second, slower process appeared only in the OD/OH re-exchange followed by FTIR, and it still continued after several weeks of immersion in hbox {H}_2hbox {O}. SANS could not detect any significant difference between the never-dried and dried/rewetted samples, whereas FTIR revealed a small portion of OD groups that resisted the re-exchange and this portion became larger with drying.Graphic abstract
Highlights
Wood and other cellulosic materials are highly sensitive to water
We showed that small-angle neutron scattering (SANS) is suitable for time-resolved studies of water-accessibility at specific levels of the hierarchical plant cell wall structure
SANS was not able to distinguish between never-dried and dried/rewetted wood samples based on the aggregation state of cellulose microfibrils
Summary
Wood and other cellulosic materials are highly sensitive to water. Moisture content governs the physical properties of wood as well as its susceptibility to fungal degradation or chemical treatments (Brischke and Alfredsen 2020; Dinwoodie 2000; Jakes et al 2019). Water-accessibility, diffusion kinetics, and structural effects of moisture changes are extremely important for more developed applications utilizing wood, including pulp and paper as well as various types of cellulose nanomaterials (Ajdary et al 2020; Heise et al 2020; Salmen and Stevanic 2018). It is not clear if specific locations in the fibrillar architecture are more accesible to water than others. This could mean for instance that the accessibility differs between the inner parts of microfibril bundles and their outer surface, as has been proposed for pulps (Lindh and Salmen 2017; Lindh et al 2017)
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
