Centrifuge fractionation during purification of cellulose nanocrystals after acid hydrolysis and consequences on their chiral self-assembly

Anna J Svagan; Francisco Vilaplana; Torbjörn Pettersson; Prasaanth Ravi Anusuyadevi; Gunnar Henriksson; Mikael Hedenqvist

doi:10.1016/j.carbpol.2023.121723

Centrifuge fractionation during purification of cellulose nanocrystals after acid hydrolysis and consequences on their chiral self-assembly

Carbohydr Polym. 2024 Mar 15:328:121723. doi: 10.1016/j.carbpol.2023.121723. Epub 2023 Dec 20.

Authors

Anna J Svagan¹, Francisco Vilaplana², Torbjörn Pettersson³, Prasaanth Ravi Anusuyadevi⁴, Gunnar Henriksson³, Mikael Hedenqvist³

Affiliations

¹ Royal Institute of Technology (KTH), Dept. of Fibre and Polymer Technology, Stockholm, Sweden. Electronic address: svagan@kth.se.
² Royal Institute of Technology (KTH), Dept. of Chemistry, Div. Glycoscience, Albanova University Centre, Stockholm, Sweden; Royal Institute of Technology (KTH), Wallenberg Wood Science Centre (WWSC), Stockholm, Sweden.
³ Royal Institute of Technology (KTH), Dept. of Fibre and Polymer Technology, Stockholm, Sweden.
⁴ Royal Institute of Technology (KTH), Dept. of Fibre and Polymer Technology, Stockholm, Sweden; Materials Science and Engineering Department (MSE), Faculty of Mechanical, Maritime and Materials Engineering (3mE), Delft University of Technology, 2628 CD Delft, the Netherlands.

PMID: 38220326
DOI: 10.1016/j.carbpol.2023.121723

Abstract

The inherent colloidal dispersity (due to length, aspect ratio, surface charge heterogeneity) of CNCs, when produced using the typical traditional sulfuric acid hydrolysis route, presents a great challenge when interpreting colloidal properties and linking the CNC film nanostructure to the helicoidal self-assembly mechanism during drying. Indeed, further improvement of this CNC preparation route is required to yield films with better control over the CNC pitch and optical properties. Here we present a modified CNC-preparation protocol, by fractionating and harvesting CNCs with different average surface charges, rod lengths, aspect ratios, already during the centrifugation steps after hydrolysis. This enables faster CNC fractionation, because it is performed in a high ionic strength aqueous medium. By comparing dry films from the three CNC fractions, discrepancies in the CNC self-assembly and structural colors were clearly observed. Conclusively, we demonstrate a fast protocol to harvest different populations of CNCs, that enable tailored refinement of structural colors in CNC films.

Keywords: Cellulose nanocrystals; Fractionation; Structural colors; Sulfuric acid hydrolysis.