Improvement of nanodispersibility of oven-dried TEMPO-oxidized celluloses in water

Takaichi, Satoshi; Saito, Tsuguyuki; Tanaka, Ryouichi; Isogai, Akira

doi:10.1007/s10570-014-0444-7

Cited by 80 publications

(58 citation statements)

References 31 publications

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“…[4][5][6][7][8][9][10] The starting materials for such clear transparent nanopaper with low haze include holocellulose pulp, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidized pulp, and carboxymethylated pulp. [11][12][13][14][15] Among them, clear transparent nanopaper from holocellulose pulp is one of the most promising candidates for exible electronic device substrates because of the high thermal resistance.…”

Section: Introductionmentioning

confidence: 99%

Clear transparent cellulose nanopaper prepared from a concentrated dispersion by high-humidity drying

2018

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Optically transparent cellulose nanopaper is a promising candidate for flexible device substrates because of its light weight, surface smoothness, and high dimensional stability with respect to temperature.Conventionally, clear transparent nanopaper has been fabricated from cellulose nanofiber dispersions with quite low concentration: less than 0.5 wt%. However, this diluteness leads to several problems, such as huge energy consumption and long operation time for drying. Therefore, nanopaper should be fabricated from a concentrated dispersion to mitigate these problems. In this study, transparent nanopaper was fabricated from cellulose nanofiber dispersions with various concentrations (0.24-1.81 wt%). Optical experiments revealed that the haze of the transparent nanopaper increased monotonically with cellulose nanofiber dispersion concentration, when the cellulose nanofiber dispersion was prepared from holocellulose pulp and conventional over-drying was applied. Based on our insight into the origin of this increase in the haze of transparent nanopaper, we developed highhumidity drying, which successfully produced clear transparent nanopaper from a concentrated dispersion without prolonged drying time.

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Section: Introductionmentioning

confidence: 99%

Clear transparent cellulose nanopaper prepared from a concentrated dispersion by high-humidity drying

2018

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“…TOC−NaClO 2 samples were also prepared from cotton linters cellulose by the same method described above but with different amounts of NaClO (1.25 and 5 mmol/g cellulose) in the TEMPO-mediated oxidation. TOC−NaBH 4 samples were prepared from SBKP and cotton linters cellulose by onepot TEMPO-mediated oxidation in water at pH 10 under various conditions and NaBH 4 reduction in the same container for 3 h. 29 Mechanical Disintegration. A 0.1% w/v suspension of TOC− NaClO 2 (100 mL) was sonicated for 10−120 min using an ultrasonic homogenizer (UTS300T, Nihon Seiki, Tokyo, Japan) at 19.5 kHz and 300 W output power to prepare TOCNs.…”

Section: ■ Introductionmentioning

confidence: 99%

Molecular Mass and Molecular-Mass Distribution of TEMPO-Oxidized Celluloses and TEMPO-Oxidized Cellulose Nanofibrils

et al. 2015

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Native wood cellulose was oxidized by 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation, and the fibrous TEMPO-oxidized celluloses (TOCs) thus obtained were disintegrated in water to prepare TOC nanofibrils (TOCNs). The carboxyl groups of TOCs and TOCNs were methyl-esterified, and the methylated samples were dissolved in 8% LiCl/N,N-dimethylacetamide for size-exclusion chromatography/multiangle laser-light scattering (SEC-MALLS) analysis to obtain their molecular-mass (MM) values and MM distributions (MMDs). The results showed that remarkable depolymerization occurred in TOCs and TOCNs and depended on the oxidation and sonication conditions. Because single peaks without bimodal patterns were observed in the MMDs for all of the TOC and TOCN samples, depolymerization may have randomly occurred on whole cellulose molecules and oxidized cellulose molecules in the microfibrils during these treatments. Compared with the MM values obtained by SEC-MALLS, the intrinsic viscosities of TOCs dissolved in 0.5 M copper ethylenediamine solution provided lower MM values owing to depolymerization during the dissolution and postreduction processes.

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“…TOCNs were prepared using a TEMPO/NaBr/NaClO system with 10 mmol of NaClO per gram of wood cellulose. TEMPO‐mediated oxidation was performed in water at pH 10 for 4 h. After successive washing steps using deionized water, the fibrous TEMPO‐oxidized cellulose (TOC) was reduced with NaBH 4 (0.1 g per gram of pulp) in water at pH 10 for 3 h to convert the remaining aldehydes and ketones to hydroxyls, followed by thorough washing with deionized water by filtration and centrifugation. The TOC thus obtained had a carboxylate content of 1.66 ± 0.14 mmol g −1 , measured by conductometric titration .…”

Section: Methodsmentioning

confidence: 99%

Optimization of preparation of thermally stable cellulose nanofibrils via heat‐induced conversion of ionic bonds to amide bonds

Lavoine

Bras

Saito

et al. 2017

J. Polym. Sci. Part A: Polym. Chem.

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Improving the thermal stability of nanocelluloses is important for practical applications such as melt compounded nanocellulose‐reinforced polymer composites and flexible substrates for nanocellulose‐containing electronic devices. Here, we report optimum conditions for a straightforward surface modification strategy for improving the thermal stability of 2,2,6,6‐tetramethypiperidine‐1‐oxyl (TEMPO)‐oxidized cellulose nanofibrils (TOCNs); the heat‐induced conversion of TOCN alkyl ammonium carboxylates to amides. Different amine‐terminated compounds (R‐NH2) were grafted onto the surface of TOCNs under aqueous conditions. The influences of R‐NH2 molecular weight, R‐NH2/TOCN‐COOH molar ratio, and thermal stability of R‐NH2 on the properties of the grafted TOCN films were investigated through infrared spectroscopy and thermogravimetric analysis. For maximum thermal improvement of up to 90 °C, complete ionic bonding of TOCN carboxy groups with R‐NH2 was required, as well as proper selection of the R‐NH2 compound. A controlled heating process was also needed to achieve effective ionic‐to‐amide bond conversion. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1750–1756

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Improvement of nanodispersibility of oven-dried TEMPO-oxidized celluloses in water

Cited by 80 publications

References 31 publications

Clear transparent cellulose nanopaper prepared from a concentrated dispersion by high-humidity drying

Clear transparent cellulose nanopaper prepared from a concentrated dispersion by high-humidity drying

Molecular Mass and Molecular-Mass Distribution of TEMPO-Oxidized Celluloses and TEMPO-Oxidized Cellulose Nanofibrils

Optimization of preparation of thermally stable cellulose nanofibrils via heat‐induced conversion of ionic bonds to amide bonds

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