Comprehensive Study of Preparation of Carboxy Group-Containing Cellulose Fibers from Dry-Lap Kraft Pulps by Catalytic Oxidation with Solid NaOCl

Hou, Gaoyuan; Chitbanyong, Korawit; Takeuchi, Miyuki; Shibata, Izumi; Isogai, Akira

doi:10.1021/acssuschemeng.3c04750

Cited by 11 publications

(1 citation statement)

References 44 publications

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“…The gels were suspended in water and subjected to high-pressure homogenization at 150 MPa three times to prepare a transparent TEMPO–CNF-COOH/water dispersion at 0.95 wt % solid content . The carboxy content of the TEMPO–CNFs-COOH was 1.5 mmol/g, when determined by the electric conductivity method …”

Section: Materials and Methodsmentioning

confidence: 99%

Silicone Oil/Water Pickering Emulsions with Surface-Hydrophobized Cellulose Nanofibers Formed via In Situ Homogenization with Amino-Silicone

Takeuchi,

Hara,

Hasegawa

et al. 2024

ACS Appl. Polym. Mater.

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The preparation of stable silicone oil/water emulsions is highly challenging because of the large difference in surface tension between the two liquids. Stable Pickering silicone oil/water emulsions were prepared by high-pressure homogenization of silicone oil/cellulose nanofibers/amino-silicone/water mixtures. TEMPO-oxidized cellulose nanofibers (TEMPO− CNFs) (TEMPO: 2,2,6,6-tetramethylpiperidine-1-oxyl radical) with protonated carboxy groups, TEMPO−CNF-COOH, nanodispersed in water and amine groups in amino-silicone molecules were ionically linked in situ during homogenization treatment of the mixtures to form partly surface-hydrophobized TEMPO− CNFs by neutralization on the silicone oil droplet surfaces. More than 99% of the TEMPO−CNFs present in the systems were adsorbed on the silicone oil droplet surfaces in combination with amino-silicone and existed at the silicone oil/water interfaces. As a result, stable o/w Pickering emulsions with small and homogeneous volume-mean diameters (0.3−0.6 μm) were obtained, maintaining the droplet surfaces to have highly negative charges (−50 mV) owing to the dissociated carboxy groups of TEMPO− CNFs in water. When the as-prepared silicone oil Pickering emulsion was coated on glass plates and dried, transparent, water/ moisture-resistant, and strongly water-repellent films were obtained. Thus, the Pickering emulsions prepared in this study are possibly used as coating or painting materials to continuously keep windows, glassware, and mirrors in a clean state.

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Section: Materials and Methodsmentioning

confidence: 99%

Silicone Oil/Water Pickering Emulsions with Surface-Hydrophobized Cellulose Nanofibers Formed via In Situ Homogenization with Amino-Silicone

Takeuchi,

Hara,

Hasegawa

et al. 2024

ACS Appl. Polym. Mater.

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Distribution of carboxy groups in TEMPO-oxidized cellulose nanofibrils prepared from never-dried Japanese cedar holocellulose, Japanese cedar-callus, and bacterial cellulose

Ono,

Horikawa,

Takeuchi

et al. 2024

Cellulose

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We prepared 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized samples from never-dried Japanese cedar (JC) holocellulose, JC-callus, and bacterial cellulose (BC). The original never-dried samples and their TEMPO-oxidized products were characterized by neutral sugar composition analysis. TEMPO-oxidized cellulose nanofibrils (TEMPO-CNFs) were prepared from the TEMPO-oxidized samples by ultrasonication in water. The carboxy groups in TEMPO-CNFs were position-selectively esterified with 9-anthryl diazomethane (ADAM) to prepare TEMPO-CNF-COOCH2-C14H9 samples, which had UV absorption peak at 365 nm. The mass-average degree of polymerization (DPw) values of 1% lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) solutions of the original samples were determined by size-exclusion chromatography in combination with multi-angle laser-light scattering, ultraviolet absorption, and refractive index detection (SEC/MALLS/UV/RI), and were 5490, 2660, and 2380 for the JC holocellulose, JC-callus, and BC samples, respectively. The TEMPO-CNF-COOCH2-C14H9 sample solutions in 1% LiCl/DMAc were analyzed by SEC/MALLS/UV/RI to obtain SEC elution patterns. The patterns corresponded to the molar mass and carboxy group distributions of the samples, which were detected by RI and UV absorption of anthryl groups, respectively. The carboxy groups existed in the entire molar mass distribution regions of all the TEMPO-CNF samples, although their lower molar mass regions contained higher carboxy group densities. The obtained results indicate that random depolymerization occurred on the cellulose microfibril surfaces at the initial stage of TEMPO-catalyzed oxidation and/or ultrasonication in water. This depolymerization mechanism can explain all the obtained SEC-elution patterns of the TEMPO-CNFs, without considering the presence of periodically disordered regions in the cellulose microfibrils of the never-dried cellulose samples. Graphical abstract

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TEMPO/CaBr2/Ca(OCl)2 oxidation of hardwood bleached kraft pulp in water at pH 10 with aqueous Ca(OH)2 solution

Hou,

Chitbanyong,

Takeuchi

et al. 2024

Cellulose

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The conventional TEMPO/NaBr/NaOCl system for oxidation of cellulose to prepare nanocellulose materials has some shortcomings in terms of controlling side reactions and clogging in washing/filtration process. A new TEMPO/CaBr2/Ca(OCl)2 system was then developed to oxidize a hardwood bleached kraft pulp (HBKP) in water at pH 10 (TEMPO = 2,2,6,6-tetramethylpiperidine-1-oxyl radical). An aqueous Ca(OH)2 solution was used to continuously control the reaction mixture at pH 10. After oxidation, the reaction mixture containing the oxidized products and chemicals was directly filtered on a 40-μm-mesh nylon filter and the water-insoluble oxidized products on the filter were washed with water without any clogging. The carboxy content increased to 1.5 mmol/g and the mass recovery ratio decreased to 87.7% as the amount of Ca(OCl)2 was increased to 10.0 mmol/g-HBKP. The oxidized products contained calcium ions but almost no chloride ions, indicating that they comprised almost pure –(COO)2Ca groups. The ready filtration and washing of the oxidized products was probably owing to the low degree of dissociation of the –(COO)2Ca groups in water. The X-ray powder diffraction (XRD) and solid-state carbon 13 nuclear magnetic resonance (13C-NMR) analyses revealed that the crystallinities and crystal widths of the original cellulose I structure were mostly retained in the oxidized products. However, size-exclusion chromatography and viscosity analyses revealed that substantial depolymerization occurred on the cellulose and oxidized cellulose molecules in the products, as in TEMPO/NaBr/NaOCl-oxidized products. Graphical Abstract

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Comprehensive Study of Preparation of Carboxy Group-Containing Cellulose Fibers from Dry-Lap Kraft Pulps by Catalytic Oxidation with Solid NaOCl

Cited by 11 publications

References 44 publications

Silicone Oil/Water Pickering Emulsions with Surface-Hydrophobized Cellulose Nanofibers Formed via In Situ Homogenization with Amino-Silicone

Silicone Oil/Water Pickering Emulsions with Surface-Hydrophobized Cellulose Nanofibers Formed via In Situ Homogenization with Amino-Silicone

Distribution of carboxy groups in TEMPO-oxidized cellulose nanofibrils prepared from never-dried Japanese cedar holocellulose, Japanese cedar-callus, and bacterial cellulose

TEMPO/CaBr2/Ca(OCl)2 oxidation of hardwood bleached kraft pulp in water at pH 10 with aqueous Ca(OH)2 solution

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