Individualization of Nano-Sized Plant Cellulose Fibrils by Direct Surface Carboxylation Using TEMPO Catalyst under Neutral Conditions

Abstract

A new catalytic oxidation using 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) and NaClO is applied to hardwood cellulose in water at 60 °C and pH 6.8 with NaClO(2) used as a primary oxidant. The oxidized celluloses with carboxylate content of approximately 0.8 mmol/g were convertible to highly crystalline and individual fibrils 5 nm in width and at least 2 μm in length by disintegration in water. The oxidized celluloses had no aldehyde groups, and high degrees of polymerization of more than 900. Solid-state (13)C NMR and X-ray analyses revealed that the C6 carboxylate groups formed are selectively present on the crystalline fibril surfaces at high densities. Films prepared from the dispersions were transparent and flexible, and exhibited a high tensile strength of 312 MPa even at a low density of 1.47 g/cm(3).

Photo-patternable and transparent films using cellulose nanofibers for stretchable origami electronics

“…Typically, a pristine cellulose film is vulnerable to water 29 and, therefore, is incompatible with water-based solution processes. The hybrid film, however, shows an increased contact angle of the film from 42°to 86°, indicating that the remaining epoxy enhances the hydrophobicity of the hybrid (Supplementary Figure S8).…”

“…19,20 Individual singular nanofibers of cellulose exhibit low CTE, which is comparable to quartz glass, and an outstanding Young's modulus, which is higher than that of aluminum and glass fibers. 21,22 Although dense aggregates of cellulose nanofibers (CNFs) can form flexible, transparent films for electronic devices, [23][24][25][26] there currently are still substantial challenges to the practical application of CNF films, such as (i) incompatibility with high-temperature processing (o200°C), 27 (ii) optical haze (420% in visible light wavelengths) 28 derived from highly porous microstructures, (iii) poor water resistance (o28°in water contact angle), 26,29 (iv) difficulty in forming complex, fine shapes and (v) limits in mechanical stretchability. To the best of our knowledge, the potential of CNF to provide stretchable but reliable electronic devices is yet unexplored.…”

Predicting the capability of carboxylated cellulose nanowhiskers for the remediation of copper from water using response surface methodology (RSM) and artificial neural network (ANN) models

“…The proof of the negative surface charge induced by the modification step comes from zeta potential measurements where nanoparticles with a high zeta potential (greater than ±25 mV) are electrically stabilized while nanoparticles with low zeta potential tend to flocculate or coagulate (Saito et al, 2009). The average zeta potentials for the unmodified and modified CNWs were -37.6 mV and -74.4 mV, respectively.…”

Obtenção e caracterização de PLA reforçado com nanocelulose.

“…No entanto, na literatura as terminologias NFCs e MFCs são utilizadas indiscriminadamente, e por vezes podem ser confundidas. [6,18,23] …”

“…Além disso, há a presença dos picos característicos da celulose I β em 2θ=14,8° e 16,3° referentes aos planos (11 ̅ 0) e (110). [23,38] Ainda pode-se observar um ombro localizado ao redor de 2θ = 21° mais pronunciado nas amostras das NCs, que representa uma reflexão do plano (102/012) e um pico bem definido a 2θ = 34° referente ao plano (040). [38] Entretanto, observam-se picos adicionais na curva pertencente às NCs Em conformidade com a literatura [4,94] …”