Lian-Hua Fu

Cellulose/CaCO3 nanocomposites: microwave ionic liquid synthesis, characterization, and biological activity.

The purposes of this article are to synthesize the biomass-based hybrid nanocomposites using green method in green solvent and evaluate its biological activity. In this paper, microwave-assisted ionic liquid method is applied to the preparation of cellulose/CaCO(3) hybrid nanocomposites in the alkali extraction cellulose using CaCl(2) and Na(2)CO(3) as starting reactants. The ionic liquid acts as the excellent solvent for absorbing microwave and the dissolution of cellulose, and the synthesis of cellulose/CaCO(3) nanocomposites. The influences of reaction parameters such as the cellulose concentration and the types of solvent on the products were investigated. The increasing cellulose concentration favored the growth of CaCO(3). The morphologies of CaCO(3) changed from polyhedral to cube to particle with increasing cellulose concentration. Moreover, the solvents had an effect on the shape and dispersion of CaCO(3). Cytotoxicity experiments demonstrated that the cellulose/CaCO(3) nanocomposites had good biocompatibility and could be a candidate for the biomedical applications.

Compare study CaCO3 crystals on the cellulose substrate by microwave-assisted method and ultrasound agitation method

The purposes of this article were to investigate the influences of synthesis strategy on the CaCO(3) crystals on the cellulose substrate. In this study, CaCO(3) crystals were synthesized using cellulose as matrix by the microwave-assisted method and ultrasound agitation method, respectively. The CaCO(3) crystals on the cellulose substrate were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Experimental results demonstrated that the synthesis strategy had a dramatically influences on the phase, microstructure, morphology, thermal stability, and biological activity of the CaCO(3) crystals. The pure phase of vaterite spheres with the diameter of about 320-600nm were obtained by ultrasound agitation method, meanwhile, the mixed phases of calcite and vaterite with the diameter of about 0.82-1.24μm were observed by microwave-assisted method. In view of experimental results, one can conclude that the ultrasound agitation method do more favors to the synthesis of CaCO(3) crystals with uniform morphology and size, compared with microwave-assisted method. Furthermore, cytotoxicity experiments indicated that the CaCO(3) crystals on the cellulose substrate had good biocompatibility and could be a candidate for the biomedical applications.

Why to synthesize vaterite polymorph of calcium carbonate on the cellulose matrix via sonochemistry process

Vaterite is an important biomedical material due to its features such as high specific surface area, high solubility, high dispersion, and small specific gravity. The purposes of this article were to explore the growth mechanism of vaterite on the cellulose matrix via sonochmistry process. In the work reported herein, the influences of experimental parameters on the polymorph of calcium carbonate were investigated in detail. The calcium carbonate crystals on the cellulose matrix were characterized by means of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). Experimental results revealed that all the reactants, solvent, and synthesis method played an important role in the polymorph of calcium carbonate. The pure phase of vaterite polymorph was obtained using Na2CO3 as reactant in ethylene glycol on the cellulose matrix via sonochmistry process. Based on the experimental results, one can conclude that the synthesis of vaterite polymorph is a system process.

Selective synthesis of Fe3O4, γ-Fe2O3, and α-Fe2O3 using cellulose-based composites as precursors

Iron oxide with various phases such as Fe3O4, γ-Fe2O3, and α-Fe2O3 has been selective successfully synthesized using cellulose-based composites as precursors, which were obtained at 180 °C for 45 min by the microwave-hydrothermal method. The products were characterized with X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TG), derivative thermogravimetric analysis (DTG), X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Fe3O4, γ-Fe2O3, and α-Fe2O3 could be selectively synthesized by changing the calcination temperature and atmosphere. It was found that Fe3O4 was obtained in the N2 atmosphere. However, γ-Fe2O3 and α-Fe2O3 were observed at 300 and 500 °C for 3 h in the air atmosphere, respectively. The as-synthesized Fe3O4 and γ-Fe2O3 displayed superparamagnetic characteristics at room temperature via the magnetization measurement. The methylene blue (MB) adsorption capacity of γ-Fe2O3 (air 300 °C) can reach 98.72% and the adsorption isotherms better fitted Freundlich isotherm models. This work provided a promising strategy for the synthesis of metal and carbon/metal composites using biomass as a precursor.

Microwave synthesis of cellulose/CuO nanocomposites in ionic liquid and its thermal transformation to CuO.

The purpose of this study is to develop a green strategy to synthesize the cellulose-based nanocomposites and open a new avenue to the high value-added applications of biomass. Herein, we reported a microwave-assisted ionic liquid route to the preparation of cellulose/CuO nanocomposites, which combined three major green chemistry principles: using environmentally friendly method, greener solvents, and sustainable resources. The influences of the reaction parameters including the heating time and the ratio of cellulose solution to ionic liquid on the products were discussed by X-ray powder diffraction, Fourier transform infrared spectrometry, and scanning electron microscopy. The crystallinity of CuO increased and the CuO shape changed from nanosheets to bundles and to particles with increasing heating time. The ratio of cellulose solution to ionic liquid also affected the shapes of CuO in nanocomposites. Moreover, CuO crystals were obtained by thermal treatment of the cellulose/CuO nanocomposites at 800 °C for 3 h in air.

Compared study on the cellulose/CaCO3 composites via microwave-assisted method using different cellulose types

The purposes of this study were to explore the influences of different cellulose types on the cellulose/CaCO3 composites, which were synthesized via the microwave-assisted method by using alkali extraction cellulose and microcrystalline cellulose, respectively. Experimental results demonstrated that the types of cellulose played an important role in the microstructure and morphologies of the cellulose/CaCO3 composites. The composites consisted of cellulose and pure phase CaCO3 (calcite). The sample synthesized using microcrystalline cellulose had better crystallinity than that of the sample using alkali extraction cellulose. The cellulose fibers and CaCO3 particles were observed using alkali extraction cellulose. However, using microcrystalline cellulose instead of alkali extraction cellulose, the cellulose with irregular shape and CaCO3 microspheres were obtained. Therefore, choosing appropriate cellulose types is very important for the formation of cellulose/CaCO3 composites. Furthermore, the Raman spectra of the cellulose/CaCO3 composites were also researched.

Environmentally friendly microwave ionic liquids synthesis of hybrids from cellulose and AgX (X = Cl, Br)

The purpose of this article was to explore an environmentally friendly strategy to synthesis of biomass-based hybrids. Herein, microwave-assisted ionic liquids method was applied to fabricate the hybrids from cellulose and AgX (X=Cl, Br) using cellulose and AgNO3. The ionic liquids act simultaneously as a solvent, a microwave absorber, and a reactant. Ionic liquids provided Cl(-) or Br(-) to the synthesis of AgCl or AgBr crystals; thus no additional reactant is needed. The products are characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and differential thermal analysis (DTA). The cellulose-Ag/AgCl hybrid and cellulose-Ag/AgBr hybrid were also obtained by using cellulose-AgCl and cellulose-AgBr hybrids as precursors. This environmentally friendly microwave-assisted ionic liquids method is beneficial to the hybrids with high dispersion.

Microwave-assisted rapid synthesis and characterization of CaF2 particles-filled cellulose nanocomposites in ionic liquid

In this article, we try to compound cellulose/alkali earth metal fluorides (MF2, M=Ca, Mg, Sr, Ba) nanocomposites via microwave-assisted ionic liquid method, wherein cellulose/CaF2 and cellulose/MgF2 were successfully synthesized through this method while cellulose/SrF2 and cellulose/BaF2 could not be synthesized. We focused on the synthesis of cellulose/CaF2 and investigated the influences of the different time and different temperature for the synthesis of cellulose/CaF2 nanocomposites. The influence of different heating methods such as oil-bath heating method was also studied. Ionic liquid ([Bmim][BF4]) was used for dissolving microcrystalline cellulose and providing the source of fluoride ionic and the alkali earth metal nitrate (Ca(NO3)2, Mg(NO3)2, Sr(NO3)2, and Ba(NO3)2) was used as the reaction initiator. They were investigated by X-ray powder diffraction (XRD), Fourier transform infrared spectrometry (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TG), derivative thermogravimetric (DTG), and energy-dispersive X-ray spectra (EDS). The different heating modes have influence on the morphology and property. The different temperature and heating time also have a certain influence on the morphology and crystallinity of calcium fluoride.

Hydrothermal synthesis, characterization, and bactericidal activities of hybrid from cellulose and TiO2

The purpose of this study was to explore a new strategy to improve the high value-added applications of biomass. Hybrid from cellulose and titanium dioxide (TiO2) was successfully prepared by using tetra-n-butyl titanate and cellulose solution via a hydrothermal method at 180°C for 24h. The phase, microstructure, morphology, and thermal stability of the hybrid were characterized by X-ray powder diffraction (XRD), Fourier transform infrared spectrometry (FT-IR), thermogravimetric analysis (TGA), differential thermal analysis (DTA), and scanning electron microscopy (SEM). The influences of the tetra-n-butyl titanate concentration and the types of solvent on the products were investigated. The TiO2 nanoparticles were dispersed on the surface of cellulose and/or in the cellulose matrix. The hybrid possessed an antimicrobial activity against the model microbes Escherichia coli (Gram-negative) and Staphylococcus aureus (Gram-positive), and were a promising antimicrobial material for the applications in the biomedical field.

Synthetic self-assembled homogeneous network hydrogels with high mechanical and recoverable properties for tissue replacement

Development of hydrogels with high mechanical and recoverable properties under physiological conditions is of great importance for broadening and improving their potential applications in load-bearing artificial soft tissues. Inspired by the self-assembly of chemical entities, homogeneous network hydrogels, which contain over 90 wt% water, were synthesized via covalent cross-linking of poly(vinyl alcohol) (PVA) and poly(vinyl pyrrolidone) (PVP) triggered by microwave-assisted treatment. A structurally homogeneous network results in an evenly distributed stress that endures high strains with minimal energy dissipation, which enable the hydrogels to withstand up to 1.16 MPa of tensile stress, over seven-fold stretch length with negligible hysteresis, and sustain cyclic compression following high amplitude deformation. It is of importance for tissue replacement that the hydrogels retain these excellent properties under physiological conditions.