Observing microfibril bundles in wood by small-angle neutron scattering

Paavo Penttilä, Michael Altgen, Muhammad Awais, Aleksi Zitting, Monika Österberg, Ralf Schweins, Lauri Rautkari

Research output: Contribution to conferencePaperScientific

Abstract

Observing microfibril bundles in wood by smallangle neutron scattering
Cellulose is present in the cell walls of wood in the form of partially crystalline microfibrils, with a thickness of 2–3 nm. Lateral aggregation of the microfibrils into bundles, also termed macrofibrils, in the secondary cell walls has been reported by various methods (Sarkar et al. 2009; Adobes-Vidal et al. 2020), including atomic force microscopy, electron microscopy and electron tomography. The lateral size of microfibril bundles is usually in the range 15–20 nm, with some hemicelluloses and water ncluded within the bundle. However, none of the methods used so far has been able to observe these structures in their truly native state, as part of an intact cell wall structure and hydrated by liquid water.

Neutron and X-ray scattering are excellent tools for non-invasive characterization of the hierarchical structure of wood and other cellulosic materials (Rongpipi et al. 2019). With these methods, the properties of cellulose crystals and the packing of microfibrils can be analysed under various external conditions such as different humidity levels (Penttilä et al. 2020a). In the current work, we utilized small-angle neutron scattering (SANS) together with contrast variation by poly(ethylene glycol) (PEG) to assign a specific contribution in the SANS intensities of native wood to the outer dimensions of cellulose microfibril bundles (Penttilä et al. 2020b). This allowed us to detect the presence of microfibril bundles in the cell walls of different types of wood and to determine their diameter also in wood samples without PEG.
Original languageEnglish
Publication statusPublished - 2020
MoE publication typeNot Eligible
EventAnnual Meeting of the Northern European Network for Wood Science and Engineering - Virtual, Online, Finland
Duration: 1 Dec 20202 Dec 2020

Conference

ConferenceAnnual Meeting of the Northern European Network for Wood Science and Engineering
Abbreviated titleWSE
Country/TerritoryFinland
CityVirtual, Online
Period01/12/202002/12/2020

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