Synthesis and characterization of cellulose derivatives prepared in NaOH/urea aqueous solutions

Zhou, Jinping; Zhang, Lina; Deng, Qing‐Hai; Wu, Xiaojun

doi:10.1002/pola.20431

Cited by 74 publications

(49 citation statements)

References 31 publications

(42 reference statements)

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“…This result indicates that no chemical reaction occurred and that no new substance was produced during the pretreatment or mechanical refining process. The final product was cellulose itself and not a derivative of cellulose (Zhou et al 2004;Cai and Zhang 2005;Wang et al 2016). While the cellulose fibers pretreated by 64 wt% sulfuric acid or TEMPO oxidation, the partial primary hydroxyl group will undergo esterification and oxidized to carboxyl hydroxyl groups ,respectively (Wang et al 2007;Isogai et al 2011).…”

Section: Ftir Analysismentioning

confidence: 99%

Preparation and Characterization of Nanocellulose Fibers from NaOH/Urea Pretreatment of Oil Palm Fibers

Luo¹,

Wang²

2017

BioResources

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A facile method is reported to prepare nanocellulose fibers from oil palm trunk fibers. The fibers were pretreated 2 hours with NaOH/urea solution, and the fully swelled fibers were mechanically treated through highpressure homogenization to obtain nanocellulose. The nanocellulose fibers were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). FTIR results revealed that there was no obvious difference between the spectra of the bleached fibers (BF), pretreated cellulose fibers (PCF), and cellulose nanofibers (NCF), which indicated that the pretreatment process is a non-derivative reaction. The crystallinity of PCF and NCF decreased and contained the cellulose I crystal structure. The PCF presented both a distorted structure and a coarser surface. The resulting NCF were approximately 10 nm to 100 nm in diameter with the length varying from hundreds of nanometers to several micrometers, as observed by SEM. The thermal degradation of NCF was 223 °C with about 20% weight loss, and the maximum degradation temperature was 338 °C. NaOH/urea showed potential as a mild solvent for preparing nanocellulose fibers.

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Section: Ftir Analysismentioning

confidence: 99%

Preparation and Characterization of Nanocellulose Fibers from NaOH/Urea Pretreatment of Oil Palm Fibers

Luo¹,

Wang²

2017

BioResources

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“…In our previous work, the NaOH/urea aqueous solution has been found to be a good solvent for cellulose, [17][18][19] and the solvent is also a suitable homogenous reaction medium for the etherification of cellulose. [20,21] In this article, we report a one-step method for the synthesis of hydrogels from unsubstitued cellulose in NaOH/urea aqueous solution by using epichlorohydrin (ECH) as crosslinker, and the structure and properties of the hydrogels were investigated.…”

Section: Full Papermentioning

confidence: 99%

Hydrogels Prepared from Unsubstituted Cellulose in NaOH/Urea Aqueous Solution

Zhou

Chang

Zhang

et al. 2007

Macromolecular Bioscience

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180

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Novel cellulose hydrogels were synthesized through a "one-step" method from cellulose, which was dissolved directly in NaOH/urea aqueous solution, by using epichlorohydrin as crosslinker. Structure and properties of the hydrogels were characterized by using SEM, NMR, and water absorption testing. The hydrogels are fully transparent and display macroporous inner structure. The equilibrium swelling ratios of the hydrogels in distilled water at 25 degrees C are in the range from 30 to 60 g H(2)O/g dry hydrogel. Moreover, the reswelling water uptake of the hydrogels could be achieved to more than 70% compared with their initial swelling states. This work provided a simple and fast method for preparing eco-friendly hydrogels from unsubstituted cellulose.

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“…The amorphous conversion of poorly water-soluble drugs as well as size reduction of their crystalline form along with intimate mixing and dispersion in hydrophilic polymers can also be achieved using solvent evaporation or particle size reduction techniques in order to improve their solubility. HPC is a cellulose ether in which some of the hydroxyl groups of the repeating glucose units are substituted with −OCH 2 CH(OH)CH 3 groups using propylene oxide (18). Therefore, HPC depicts organic as well as water solubility and hence is suitable for solvent methods to manufacture SDs (19).…”

Section: Introductionmentioning

confidence: 99%

Low-Viscosity Hydroxypropylcellulose (HPC) Grades SL and SSL: Versatile Pharmaceutical Polymers for Dissolution Enhancement, Controlled Release, and Pharmaceutical Processing

Sarode

Wang

Cote³

et al. 2012

AAPS PharmSciTech

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Abstract. Hydroxypropylcellulose (HPC)-SL and -SSL, low-viscosity hydroxypropylcellulose polymers, are versatile pharmaceutical excipients. The utility of HPC polymers was assessed for both dissolution enhancement and sustained release of pharmaceutical drugs using various processing techniques. The BCS class II drugs carbamazepine (CBZ), hydrochlorthiazide, and phenytoin (PHT) were hot melt mixed (HMM) with various polymers. PHT formulations produced by solvent evaporation (SE) and ball milling (BM) were prepared using HPC-SSL. HMM formulations of BCS class I chlorpheniramine maleate (CPM) were prepared using HPC-SL and -SSL. These solid dispersions (SDs) manufactured using different processes were evaluated for amorphous transformation and dissolution characteristics. Drug degradation because of HMM processing was also assessed. Amorphous conversion using HMM could be achieved only for relatively low-melting CBZ and CPM. SE and BM did not produce amorphous SDs of PHT using HPC-SSL. Chemical stability of all the drugs was maintained using HPC during the HMM process. Dissolution enhancement was observed in HPC-based HMMs and compared well to other polymers. The dissolution enhancement of PHT was in the order of SE>BM>HMM>physical mixtures, as compared to the pure drug, perhaps due to more intimate mixing that occurred during SE and BM than in HMM. Dissolution of CPM could be significantly sustained in simulated gastric and intestinal fluids using HPC polymers. These studies revealed that low-viscosity HPC-SL and -SSL can be employed to produce chemically stable SDs of poorly as well as highly water-soluble drugs using various pharmaceutical processes in order to control drug dissolution.

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Synthesis and characterization of cellulose derivatives prepared in NaOH/urea aqueous solutions

Cited by 74 publications

References 31 publications

Preparation and Characterization of Nanocellulose Fibers from NaOH/Urea Pretreatment of Oil Palm Fibers

Preparation and Characterization of Nanocellulose Fibers from NaOH/Urea Pretreatment of Oil Palm Fibers

Hydrogels Prepared from Unsubstituted Cellulose in NaOH/Urea Aqueous Solution

Low-Viscosity Hydroxypropylcellulose (HPC) Grades SL and SSL: Versatile Pharmaceutical Polymers for Dissolution Enhancement, Controlled Release, and Pharmaceutical Processing

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