Role of urea in alkaline dissolution of cellulose

Isobe, Noriyuki; Noguchi, Keiichi; Nishiyama, Yoshiharu; Kimura, Satoshi; Wada, Masahisa; Kuga, Shigenori

doi:10.1007/s10570-012-9800-7

Cited by 86 publications

(50 citation statements)

References 36 publications

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“…It is these low-temperature unfrozen solvent molecules that provide an essential liquid environment for chitin dissolution. It was previously suggested that NaOH interacts with chitin/cellulose, which leads to chitin/cellulose dissolution, but urea is not directly associated with NaOH and chitin/cellulose (Egal et al 2008;Hu et al 2007;Isobe et al 2013). Here, the role of urea in chitin dissolution in the NaOH/urea/ D 2 O solvent is regarded as enhancing the lowtemperature stability of NaOH aqueous solution and adjusting the NaOH concentration in the residual liquid phase so as to affect chitin dissolution.…”

Section: Dissolution Of Chitin In the Naoh/urea/d 2 O Mixture At Low mentioning

confidence: 99%

Quantitative NMR investigation on the low-temperature dissolution mechanism of chitin in NaOH/urea aqueous solution

Luo

Liang

et al. 2015

Cellulose

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The low-temperature dissolution mechanism of chitin in NaOH/urea aqueous solution has not been well established yet, especially at a temperature that lowers the crystallization temperature of both NaOH and urea. Using multiple nuclei ( 1 H, 15 N and 23 Na) nuclear magnetic resonance (NMR) methods, we find that the ternary NaOH/urea/D 2 O system, different from the fully frozen binary NaOH-D 2 O system, exhibits solid-liquid phase coexistence below -40°C, and the residual liquid phase consists of certain concentrations of NaOH (10 wt%), urea (13 wt%) and D 2 O at -40°C. Our NMR results further demonstrate that chitin dissolves in the residual liquid phase (containing 5-10 wt% NaOH and 8-12 wt% urea) at low temperatures (-40 and -70°C). An important role of urea is enhancing the low-temperature stability of NaOH aqueous solutions and then increasing the dissolution temperature range of chitin, thus providing an essential low-temperature liquid environment for chitin dissolution.

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Section: Dissolution Of Chitin In the Naoh/urea/d 2 O Mixture At Low mentioning

confidence: 99%

Quantitative NMR investigation on the low-temperature dissolution mechanism of chitin in NaOH/urea aqueous solution

Luo

Liang

et al. 2015

Cellulose

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“…The |η*| increased with an increase in RCNs content due to RCNs tethered to WPU chains. This can be explained on the basis of resistance to flow and the deformation of polymer chains imposed by tethered RCNs . The storage modulus ( G ′) increased gradually with an increase in frequency for all cases [Figure (b)].…”

Section: Resultsmentioning

confidence: 92%

Fabrication of regenerated cellulose nanoparticles/waterborne polyurethane nanocomposites

Shin

Choi

Lee

2018

J of Applied Polymer Sci

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Regenerated cellulose nanoparticles (RCNs) are ideal materials for new biomass polymer composites industries. RCNs and composites of RCNs and water‐borne polyurethane (RCN/WPU) were prepared using a facile and environmentally friendly approach without the use of any harmful chemicals. The morphological, thermal, and mechanical properties of the RCN/WPU nanocomposite were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), rheometer, wide‐angle X‐ray diffraction, and enzymatic hydrolysis. RCNs exhibited low crystallinity upon regeneration with an NaOH‐based aqueous solution, and were identified by SEM and TEM to consist of the more thermodynamically stable cellulose form. TGA showed that the thermal stability of RCN/WPU nanocomposites was increased by the addition of RCNs. Finally, enzymatic hydrolysis using cellulase indicated that the biodegradability of RCN/WPU nanocomposites was also improved. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46633.

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“…Cellulose is composed of microfibrils, each of which is an assembly of crystalline and semicrystalline cellulose covered with amorphous nanofibrils of cellulose, and the microfibrils are held together by cross‐linking hemicellulose into small polysaccharides . A possible structural modification that results from urea impregnation is supported by the IR spectra in attenuated total reflectance (ATR) mode of FP and u FP (Figure S1), which agrees with previous reports on the interactions between urea and cellulose . The appearance of new absorption bands in the IR spectrum of u FP in comparison with that of FP indicates clearly that the cellulose surface has been modified .…”

Section: Resultsmentioning

confidence: 99%

Synthesis of Titania@Carbon Nanocomposite from Urea‐Impregnated Cellulose for Efficient Lithium and Sodium Batteries

et al. 2016

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Nanostructured TiO2 and TiO2@C nanocomposites were prepared directly from urea-impregnated cellulose by a simple reaction/diffusion process and evaluated as negative electrode materials for Li and Na batteries. By direct treatment with TiCl4 under anhydrous conditions, the urea impregnation of cellulose impacts both the TiO2 morphology and the carbon left by cellulose after pyrolysis. Hierarchical TiO2 structures with a flower-like morphology grown from-and-at the surface of the cellulose fibers are obtained without any directing agent. The resulting TiO2/cellulose composite is then transformed either into pure TiO2 flowers by calcination in air at 600 °C, or into TiO2@C nanocomposites by pyrolysis under Ar at 600 °C. Electrochemical studies demonstrate that both samples can (de)insert lithium and sodium ions and are promising electrode materials.

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Role of urea in alkaline dissolution of cellulose

Cited by 86 publications

References 36 publications

Quantitative NMR investigation on the low-temperature dissolution mechanism of chitin in NaOH/urea aqueous solution

Quantitative NMR investigation on the low-temperature dissolution mechanism of chitin in NaOH/urea aqueous solution

Fabrication of regenerated cellulose nanoparticles/waterborne polyurethane nanocomposites

Synthesis of Titania@Carbon Nanocomposite from Urea‐Impregnated Cellulose for Efficient Lithium and Sodium Batteries

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