Cellulose nanocrystals to modulate the self-assembly of graphene oxide in suspension

• Published in: Materials & design Vol. 216; p. 110572
• Main Authors: Singh Raghuwanshi, Vikram, Varanasi, Swambabu, Batchelor, Warren, Garnier, Gil
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.04.2022; Elsevier
• Subjects: Cellulose nanocrystals; Graphene oxide; Isotropic; Nematic; Self-assembly; Small angle X-ray scattering; Self-assembly; Graphene oxide; Isotropic; Small angle X-ray scattering; Cellulose nanocrystals; Nematic
• ISSN: 0264-1275; 1873-4197
• DOI: 10.1016/j.matdes.2022.110572

[Display omitted] •The self-assembly ofgraphene oxide (GO) sheets and cellulose nanocrystals rods (CNC) in CNC/GO composite suspension is studied by SAXS.•Mixing isotropic and nematic phases of CNC with GO at different CNC/GO ratios shows transition from isotropic to biphasic and a nematic state.•At a higher CNC/GO ratio, the CNC rods force the GO sheets to align in the direction of the CNC nematic assembly.•This novel self-assembly mechanism of CNC-GO composites can prevent graphene aggregation on reduction for specific application. Controlling the self-assembly(SA) of cellulose nanocrystals(CNC) and graphene-oxide(GO) sheets at nanoscale is crucial for exploiting properties of both CNC and GO. The SA mechanism of GO, CNC and CNC/GO in suspension is evaluated at different concentrations and mixing ratios. SAXS determine the interparticle distance, interaction and distribution of CNC and GO to resolve the self-assembling mechanism. At lower concentrations, the GO sheets are distributed randomly and separated by a large inter-sheet distance of 83 nm with poor inter-sheet interaction. As increases the GO concentration, the inter-sheet repulsion results in a nematic arrangement with the inter-sheet distance decreasing from 83 to 52 nm. Mixing isotropic and nematic phase of CNC with GO at different CNC/GO ratio from 2 to 50 shows transitions from isotropic, to biphasic and nematic state. In isotropic state, at low CNC/GO ratio, the GO sheets are randomly distributed between the CNC rods which increases the CNC inter-rod distance from 22 to 51 nm. However, at higher CNC/GO ratios, steric repulsion from the large amount of CNC forces the GO sheets to align following the direction of CNC nematic assembly. Understanding SA mechanisms of nanostructures in CNC-GO hybrid will enable to engineer applications for sensor, electronics and diagnostics.