查找使用阿拉丁产品的科研文献

Self-assembly of cellulose nanoparticles as electrolyte additive for capillary electrophoresis separation

Dihui Huang,Qin Yang,Shanxia Jin,Qianchun Deng,Ping Zhou

In this work, a new cellulose derivative, octadecyl modified quaternized cellulose (ODMQC), was synthesized and used as additive in the background electrolyte for capillary electrophoresis. The derivative bearing hydrophobic groups and hydrophilic groups can self-assemble into a stable nano-scaled micelle structure in aqueous solution. When ODMQC was added in running buffer, the capillaries were shown to generate applicable anodal EOF over the investigated range of pH 3.0–12.0. Due to the lack of UV active groups, the ODMQC did not disturb the UV detection. It is shown that ODMQC-added capillaries allow the separation of basic proteins by reducing their adsorption onto the capillary wall. Also, the addition of ODMQC provides adequate separation of aromatic acids with low p K a values and improved separation of sulfa drugs. Moreover, it is demonstrated that the addition of ODMQC can incorporate an additional reversed-phase mechanism that improves the separation of neutral analytes.

Preparation of cotton cellulose nanofibers/ZnO/CdS nanocomposites and its photocatalytic activity

Li Jing,Cao Jun,Zhang Xiufang,Wang Song,Zheng Yingying,Pan Jiaqi,Li Chaorong

The ZnO/CdS nanocomposites have been successfully synthesized on the electrospun cotton cellulose nanofibers (CCNFs). ZnO nanorods (70–80 nm in diameter and 1 μm in length) are uniformly grown on the CCNFs by a simple hydrothermal method firstly and then different amount of CdS nanoparticles (20–30 nm in diameter) are loaded on the ZnO nanorods by the chemical bath deposition method. The visible light photocatalytic activity of ZnO/CdS nanocomposites is investigated by degradation of Rhodamine B under visible light irradiation, and it demonstrates that the photocatalytic performance of this composites is significantly enhanced compared with that of pure ZnO. Furthermore, the relatively narrow band gap and novel nanostructure of the composites are considered as the main reasons of this enhancement.

Microcrystalline cellulose as reactive reinforcing fillers for epoxidized soybean oil polymer composites

Ming He,Jianjun Zhou,Huan Zhang,Zhenyang Luo,Jianfeng Yao

Microcrystalline cellulose (MCC) and its oxidized product dialdehyde cellulose (DAC) were introduced as the reinforcing filler in epoxidized soybean oil (ESO) thermosetting polymer. The composites comprising up to 25 wt % cellulose fillers were obtained via a solution casting. The reinforcing effects of the cellulose were evaluated by microstructure analysis, dynamic mechanical analysis, and tensile and thermal stability tests. The results showed that at the same filler concentration, DAC led to higher stretching strength, modulus, and break elongation than MCC. The 5 wt % DAC loading in ESO polymer exhibits the highest toughness and thermal stability due to the good dispersion and interfacial interaction between DAC and ESO polymer matrix. The increased storage modulus and glass transition temperature also indicate the cellulose fillers impart stiffness to the composites. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 42488.

Synthesis and characterization of quaternized bacterial cellulose prepared in homogeneous aqueous solution

Hairong Zhang,Haijun Guo,Bo Wang,Silan Shi,Lian Xiong,Xinde Chen

In this work, bacterial cellulose (BC) was activated by ethylenediamine (EDA) and then dissolved in lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) aqueous solutions. The resulting transparent solution was cast on a glass plate to prepare regenerated BC. Then cationic BC was prepared homogeneously by the reaction between regenerated BC and 3-chloro-2-hydroxypropyl-trimethyl ammonium chloride (CHPTAC) in a NaOH/urea aqueous solution. Structure and properties of the BC and its products were characterized by different techniques such as X-ray diffraction (XRD), Fourier transform spectroscopy (FT-IR), scanning electron microscopy (SEM) and thermo-gravimetric analysis (TGA). The results showed that there was no significant difference between the structures of BC, activated BC and regenerated BC. The effects of different temperature and molar ratio of CHPTAC to anhydroglucose unit (AGU) on the degree of substitution (DS) value were examined. The DS values of cationic BC ranged between 0.21 and 0.51.

A physical route to porous ethyl cellulose microspheres loaded with TiO2 nanoparticles

Weiwei Cai,Hui Yang,Daxin Han,Xingzhong Guo

Porous ethyl cellulose (EC) microspheres were prepared via a physical method in oil-in-water (O/W) emulsions. The morphologies and pore structures of the resulting porous microspheres were investigated by scanning electron microscopy (SEM), mercury porosimeter and spectrometer equipped with an integrating sphere. The increase of EC amount in oil phase will increase the size of the microspheres. All the microspheres possess open macropores in the shell and interconnected pores inside the microspheres by means of phase separation. The saturation of the Ethyl acetate (EA) in external phase has an effect on the morphology of the EC particles obtained. Using EA unsaturated aqueous solution as the external water phase in the emulsion process results in the formation of porous EC particles with irregular shape. The loaded TiO 2 nanoparticles uniformly disperse in EC matrix, and slightly deceases the size and volume of interconnected pores inside the microspheres. The addition of TiO 2 nanoparticles is also proved to increase the light-scattering power of the porous EC microspheres. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131 , 40822.

Preparation, characterization, and antibacterial activities of quaternarized N-halamine-grafted cellulose fibers

Xiaoqin Chen,Zuliang Liu,Weiwei Cao,Chunyan Yong,Xiaodong Xing

A viable method for coating of cellulose fiber with quaternarized N-halamine is reported in this article. The use of quaternary ammonium salt group in combination with N-halamine group can reinforce the antibacterial activity. The chemical structure of as-synthesized N-halamine precursor 4-(Bromo-acetic acid methylester)-4-ethyl-2- oxazolidinone (BEO) was characterized by 1 H-NMR. The cellulose fibers were characterized by Fourier transform infrared spectra and X-ray photoelectron spectra. The spectra data confirmed that the quaternarized N-halamine-grafted cellulose fibers were successfully obtained. The antibacterial properties of functional fibers were challenged with both Gram positive and Gram negative bacteria. The antibacterial tests and showed that the as-prepared antibacterial cellulose fibers exhibited powerful and rapid bactericidal performance against both Gram negative E. coli and Gram positive S. aureus . © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132 , 42702.

Versatile Nickel–Lanthanum(III) Catalyst for Direct Conversion of Cellulose to Glycols

Ruiyan Sun,Tingting Wang,Mingyuan Zheng,Weiqiao Deng,Jifeng Pang,Aiqin Wang,Xiaodong Wang,Tao Zhang

Using cellulosic biomass to synthesize bulk quantities of high-value chemicals is of great interest for developing a sustainable biobased society. Especially, direct catalytic conversion of cellulose to glycols, important building blocks for polymers, remains a grand challenge. Herein, we report the development of a versatile binary nickel–lanthanum(III) catalyst for the conversion of cellulose to both ethylene glycol (EG) and propylene glycol (1,2-PG) in a yield of 63.7%, which is one of the best performances reported for this catalytic reaction. Especially, lanthanum(III) exhibited a high level of activity toward the degradation of cellulose (TON = 339) at a very low concentration (0.2 mmol/L). On the basis of density functional theory calculations and experimental analyses, we addressed a dual route for this catalytic mechanism: a major route involving the selective cracking of sugars into C2 molecules and a minor route involving the hydrogenolysis of sugar alcohols. Lanthanum(III) catalyzes the cleavage of the C2–C3 bond in glucose via sequential epimerization and 2,3-hydride shift reactions to form glycolaldehyde, the precursor of EG.

Host–guest chemistry of cyclodextrin carbamates and cellulose derivatives in aqueous solution

Xin Guo,Xiangxiang Jia,Jiaojiao Du,Longqiang Xiao,Feifei Li,Liqiong Liao,Lijian Liu

Supramolecular polymer micelles were prepared on basis of the inclusion complexation between cyclodextrin carbamates and cellulose derivatives in aqueous media. Cyclodextrin carbamates were synthesized by microwave-assisted method from cyclodextrin and urea. The urea modified cyclodextrin shows the higher yield than the physical mixture of urea/cyclodextrin in the micellization with cellulose derivatives. The supramolecular structure of the core–shell micelles was demonstrated by 1 H NMR spectra, TEM images, and fluorescence spectra. The drug release behavior of the supramolecular polymer micelles was evaluated using prednisone acetate as a model drug. The drug loaded micelles showed steady and long time drug release behavior. With these properties, the supramolecular polymer micelles are attractive as drug carriers for pharmaceutical applications.

Properties of low methoxyl pectin-carboxymethyl cellulose based on montmorillonite nanocomposite films

Wen-Xi Yu,Zhi-Wei Wang,Chang-Ying Hu,Lei Wang

Summary In this study, the low methoxyl pectin-carboxymethyl cellulose-based montmorillonite (LMP-CMC-MMT, LCM) nanocomposite films with nine ratios of LMP:CMC (from 10:0 to 0:10) and different MMT contents (1–8 wt%) were prepared. The mechanical properties, colour, opacity and water vapour permeability (WVP) of composite films were investigated. The maximum of tensile strength (TS) of composite films was 39.85 ± 2.51 MPa at LMP:CMC ratio of 4:6 and 4 wt% MMT (LCM47), which indicated the formation of hydrogen bonds between MMT and LMP-CMC. The reduction of WVP of the LCM47 composite film was 333% of that of the CMC film due to the tortuous path caused by MMT incorporation. LCM composite films had the higher b *- and Δ E *-values and lower L *-values in comparison with LMP-CMC (LC) composite films. The LCM composite films showed a decrease in transparency as MMT content increased.

Molecular simulation and experimental analysis of Al2O3-nanoparticle-modified insulation paper cellulose

Chao Tang,Song Zhang,Jingyu Xie,Cheng Lv

Polyimide/cellulose acetate core/shell electrospun fibrous membranes for oil-water separation

Wenjing Ma,Zhongfu Guo,Juntao Zhao,Qian Yu,Fang Wang,Jingquan Han,Hui Pan,Jianfeng Yao,Qilu Zhang,Sangram Keshari Samal,Stefaan C. De Smedt,Chaobo Huang

In recent years, efficient, cost effective oil-water separation technologies are highly desired due to frequent oil spill accidents. To design fibrous membranes for efficient oil-water separation, ‘flexible’ polyamide acid (PAA), being polyamide acid with ether linkages in the backbone, and ‘heavily’ fluorinated polybenzoxazine (F-PB) were synthesized. Cellulose acetate (CA) and PAA were co-axially   electrospun; the PAA core was then imidizated at high temperature to obtain core/shell structured CA/polyimide (PI) electrospun fibrous membranes; subsequently the surface of the fibers was modified with F-PB, in the presence or in absence of silica nanoparticles (SNPs). The mechanical strength, surface wettability, chemical and thermal stability, and oil-water separation potential of thus obtained PI/CA fibrous membranes were evaluated. The membranes show a much higher critical tensile stress (130   MPa) and critical tensile strain (52%), when compared with CA fibrous membranes. Due to the use of the ‘heavily’ fluorinated polybenzoxazine, the membranes are superhydrophobic with a water contact angle of 162° and an oil contact angle which approaches 0°. Interestingly, the newly designed PI/CA/F-PB-1/SNP-4 membranes can effectively separate various oil-water mixtures, solely driven by gravity, with a high flux (3106.2   ±   100   L   m −2   h −1 ) and a high separation efficiency (>99%) and thus possess great potential for oil–water separation.

Preparation and characteristic of modified double-base propellant modified with cellulose nanofibers

Zhang-Yunhua,Liu-Chuanting,Lv-Yanyan,Zhou-Zhenwen,Wang-Feijun,Shao-Ziqiang,Zuo-Yingying,Wei-Xiaolin

Cellulose nanofibers (CNFs) with high aspect ratio was prepared from wood cellulose using 2,2,6,6-tetramethylpiperidine oxygen radical (TEMPO) oxidation method. By UV, TEM, FT-IR, XRD and TG, the characterizations of CNFs were studied. The results showed that CNFs was a a hydrophilic natural nanomaterials with good suspension stability, high aspect ratio and cellulose I crystal structure. The modified double base propellant with high solid content prepared by calendering process was modified by using CNFs as nano-fillers. The results of tensile test and burning test of propellant showed that the mechanical properties and combustion performances of CNFs modified double base propellant had been improved significantly compared to conventional modified double base propellant. The tensile strength and elongation at break can be increased by nearly 34%, 45%,respectively. The burning rate of propellant can be increased by 27.5% while the pressure coefficient decreased by 20%.