Review: Periodate oxidation of wood polysaccharides—Modulation of hierarchies

Zhang

et al. 2021

Preprint

Functionality of wood has to evolve with time to adapt to the emerging needs in society. In this work, endowing electrical conductivity to the insulating wood by adding graphene into the wood matrix to form a conductive wood-graphene composite (conductive wood) via a facile and environmentally benign fabrication technique. The rationale of fabricating conductive wood is of two folds: (1) The high suitability of wood as a renewable matrix due to its porous network and mechanically robust monolithic structure. (2) The need to explore reasonable strategy to adequately translate the properties of graphene from microscopic level to macroscopic level. The conductive wood is able to preserve both the natural features of wood (to function as mechanical scaffold) and the conductivity of graphene. An outstanding electrical conductivity (volume resistivity of 36.7 Ω·cm) is achieved for the conductive wood, while it can maintain a low bulk density of 0.44 g cm-1. More significantly, the conductive wood demonstrates a highly three-dimensional anisotropic conductivity that makes it a highly versatile conductor in various applications. Hence, this lightweight conductive wood may contribute towards a great electronic revolution and as an encouraging strategy to repurpose the function of wood in this new era.

Section: Resultsmentioning

confidence: 99%

Achieving Highly Anisotropic Three-Dimensional, Lightweight, and Versatile Conductive Wood-Graphene Composite

Zhang

et al. 2021

Preprint

ACS Appl. Mater. Interfaces

“…This is potentially due to strong van der Waals interactions within the ordered cellulose structure, the heterogeneous nature of the periodate oxidation, and the lack of mechanical agitation within the liquid cell. 31 , 66 , 67 …”

Section: Resultsmentioning

confidence: 99%

Advanced Characterization of Self-Fibrillating Cellulose Fibers and Their Use in Tunable Filters

Gorur

Reid

Montanari

et al. 2021

Thorough characterization and fundamental understanding of cellulose fibers can help us develop new, sustainable material streams and advanced functional materials. As an emerging nanomaterial, cellulose nanofibrils (CNFs) have high specific surface area and good mechanical properties; however, handling and processing challenges have limited their widespread use. This work reports an in-depth characterization of self-fibrillating cellulose fibers (SFFs) and their use in smart, responsive filters capable of regulating flow and retaining nanoscale particles. By combining direct and indirect characterization methods with polyelectrolyte swelling theories, it was shown that introduction of charges and decreased supramolecular order in the fiber wall were responsible for the exceptional swelling and nanofibrillation of SFFs. Different microscopy techniques were used to visualize the swelling of SFFs before, during, and after nanofibrillation. Through filtration and pH adjustment, smart filters prepared via in situ nanofibrillation showed an ability to regulate the flow rate through the filter and a capacity of retaining 95% of 300 nm (diameter) silica nanoparticles. This exceptionally rapid and efficient approach for making smart filters directly addresses the challenges associated with dewatering of CNFs and bridges the gap between science and technology, making the widespread use of CNFs in high-performance materials a not-so-distant reality.

“…For the DAC and desulfDAC, in addition to the signals above, several Gaussian signals were added to correct for the oxidized material. The deconvolution of this new broad peak area was performed using literature describing oxidized cellulose structures (Plappert et al 2018;Nypelö et al 2021), however to fully assign these signals remains a future work. As the C1 signal is consumed during oxidation, the DO could be determined using the Eq.…”

Section: Oxidation Kinetics and Composition Of The Cncsmentioning

confidence: 99%

“…Oxidation is a common reaction for modifying CNCs. Periodate oxidation cleaves the bond in the anhydroglucose unit (AGU) between carbons in positions 2 and 3 (C2 and C3) transforming them into aldehydes and further hydrated aldehydes in water (Nypelö et al 2021). The aldehyde groups can react with vicinal hydroxyls to form hemiacetals or hemialdals (Sulaeva et al 2015).…”

Section: Introductionmentioning

confidence: 99%

The effect of sulfate half-ester groups on cellulose nanocrystal periodate oxidation

et al. 2021

Self Cite

Periodate oxidation introduces aldehyde functionality to cellulose. The use of dialdehyde cellulose has been demonstrated for crosslinking and as a chemical intermediate towards functionalized cellulose. Commercially available cellulose nanocrystals (CNCs) typically carry a surface sulfate half-ester functionality, which results from their manufacture via sulfuric acid hydrolysis and subsequent esterification. The sulfate half-ester group is a bulky group carrying a net negative charge above pH 2 that modifies the colloidal and electro-chemical properties of the CNCs. Periodate oxidation is regioselective to the bond between carbons in positions 2 and 3 in the anhydroglucose unit while the sulfate half-ester groups are mostly considered to be located in carbon in position 6. This regioselectivity could be the reason why the role played by the sulfate half-ester group on modification by periodate oxidation has not previously been elucidated. Here, the influence of the sulfate half-ester on the oxidation of CNCs, which is shown to steer the oxidation kinetics and the properties of the resulting materials, is studied. Conventional physicochemical analysis of the oxidant consumption is accompanied by elemental analysis, Fourier-transform infrared, X-ray photoelectron and solid-state nuclear magnetic resonance spectroscopy, and wide-angle x-ray scattering analyses; the zeta potential is used to characterize the colloidal properties of the suspensions and atomic force microscopy for determining particle dimensions. The presence of the sulfate half-ester group decreases the rate of oxidation. However, the content of the sulfate half-ester groups decreases when degree of oxidation reaches approx. 50%. We demonstrate that the CNC surfaces are affected by the oxidation beyond the C2–C3 bond cleavage: insight into the kinetics of the oxidation process is a prerequisite for optimizing CNC oxidation.