Face-to-face interfacial assembly of TiO2-g-C3N4 hybrid (2D TCN-A) is developed by surfactant-assisted hydrothermal treatment forming a sandwich structure of anatase TiO2 nanosheets (TiO2-A, 5–6 ...monolayers) and g-C3N4 nanosheets (∼3 monolayers). Post air-annealing is found effective for insertion of oxygen to the hybrid, which remedies the oxygen vacancies of TiO2 (B) nanosheets and converts it to anatase nanosheets. The enhanced light adsorption, increased donor density, and prolonged life of charge carries are achieved by variation of bandgap and the formation of heterojuction between the two kinds of nanosheets, facilitating separation and transfer of charge carriers. The 2D TCN-A-70 nanosheets show a high photodegradation rate of methyl orange (k app ≈ 0.189 min–1) and photocatalytic evolution rate of hydrogen (18200 μmol g–1 h–1). This 2D nanosheets hybrid is potentially useful in alleviating environmental and energy issues.
All-cellulose composite films were prepared, for the first time, from native cellulose nanowhiskers and cellulose matrix regenerated from aqueous NaOH−urea solvent system on the basis of their ...temperature-dependent solubility. The cellulose whiskers retained their needlelike morphology with mean length and diameter of 300 and 21 nm as well as native crystallinity when added to the latter solution at ambient temperature. The structure and physical properties of the nanocomposite films were characterized by scanning electron microscope, X-ray diffraction, and tensile tests. The composite films were isotropic and transparent to visible light and showed good mechanical properties as a result of the reinforcement by the whiskers. By varying the ratio of the cellulose whiskers to regenerated cellulose matrix (cellulose II), the tensile strength and elastic modulus of the nanocomposite films could be tuned to reach 124 MPa and 5 GPa, respectively. The tensile strength of the nanocomposite films could reach 157 MPa through a simple drawing process, with the calculated Hermans’ orientation parameter of 0.30. This work provided a novel pathway for the preparation of biodegradable all-cellulose nanocomposites, which are expected to be useful as biomaterials and food ingredients.
A facile method was developed for preparing size-controlled silver nanoparticles supported by pyrolytic carbon from microcrystalline cellulose (MCC). The pyrolysis of cellulose-AgNO3 mixture caused ...the oxidation of cellulose, resulting in carboxyl groups to which silver ions can bind firmly and act as nuclei for the deposition of silver nanoparticles. The structure and properties of the obtained nanocomposite were characterized by using a scanning electron microscope (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR) and X-ray diffraction (XRD). The results suggest that silver nanoparticles were integrated successfully and dispersed uniformly in the pyrolytic carbon matrix. The average particle size varied between 20 nm and 100 nm in correlation to the dose of silver nitrate and temperature of pyrolysis. The products showed high electric conductivity and strong antimicrobial activity against Escherichia coli (E. coli).
Highly porous and strong cellulose aerogels were prepared by gelation of cellulose from aqueous alkali hydroxide/urea solution, followed by drying with supercritical CO2. Their morphology, pore ...structure, and physical properties were characterized by scanning and transmission electron microscopy, X‐ray diffraction, nitrogen adsorption measurements, UV/Vis spectrometry, and tensile tests. The cellulose hydrogel was composed of interconnected fibrils of about 20 nm wide. By using supercritical CO2 drying, the network structure in the hydrogel was well preserved in the aerogel. The results are preliminary but demonstrate the ability of this method to give cellulose aerogels of large surface areas (400–500 m2 g−1) which may be useful as adsorbents, heat/sound insulators, filters, catalyst supports, or carbon aerogel precursors.
No lightweight when it comes to strength: Highly porous and strong cellulose hydrogels are obtained by dissolution of cellulose in aqueous alkali–urea solution followed by regeneration from various solvents. Drying the hydrogels gives rise to cellulose aerogels (see photo, right) which may be useful, for example, as catalyst supports.
We report a one-step and environment-friendly synthesis of platinum nanoparticles with controlled shapes and sizes using wood nanomaterials in aqueous phase without employing any other reductants, ...capping or dispersing agents. This green process affords an easy route to the production of shape-selective metal nanoparticles. The obtained spherical and cubic Pt nanoparticles and spherical Pt nanoclusters exhibit high activities in the catalytic reduction of p-nitrophenol as a model reaction.
Wood pulps with certain amounts of lignin were successfully dissolved in aqueous NaOH/urea solution by subjecting them to the dilute acid pretreatment. After the acid hydrolysis, viscosity-average ...degree of polymerization (DPv) of the pulps decreased. The results revealed that both the DPv and lignin contents influenced the dissolved proportions of wood pulps. When they were not so high, the wood pulps could almost completely dissolve with dissolved proportions >90%. In particular, the acid-pretreated unbleached kraft pulp with DPv of about 500 and lignin content of 6.9% could dissolve in NaOH/urea solvent and achieve a maximum pulp concentration of 4 wt % in the obtained lignocellulose solution. Moreover, the acid-pretreated bleached thermomechanical pulp with a high lignin content of 14.2% also almost completely dissolved. The lignocellulose films prepared from these wood pulp/NaOH/urea solutions exhibited good transparency and bendability, thus maybe promising as new biobased materials.
Hydrogels have attracted extensive attention in recent years, while it remains a great challenge to integrate excellent mechanical properties, self-adhesion, and strain sensitivity into a single ...hydrogel, especially in the wearable sensor field. In this work, a two-dimensional (2D) cellulose nanosheet (CNS)-enhanced flexible multibond cross-linked poly(acrylic acid) (PAA) hydrogel was fabricated through a facile radical-induced grafting method using Fenton reagents as an initiator. The introduction of 2D CNSs, which originated from the ball-milling exfoliation of cotton cellulose, enormously improved the mechanical properties of the PAA hydrogel because of its effective dispersion of the applied external force along the polymer chains. At a premium Fe3+/acrylic acid ratio of 2.5‰ and a cellulose content of 14% (Cel14/PAA-Fe2.50 3+), benefiting from the abundant multibonds including various covalent bonds and coordinate bonds, the mechanical and self-adhesive properties of the hydrogel were superior to those of other hydrogels. The hydrogel exhibited excellent self-adhesive ability (elongation at break = 1800%) and a durability of 500 cycles under 20, 100, and 400% strains. The existence of Fe3+ from the Fenton reagent endowed the hydrogel with excellent conductivity, evidenced by the fact that the strain sensor based on Cel n /PAA-Fe m 3+ hydrogels demonstrated stable conductivity and strain sensitivity (the gauge factor = 7.6 at 600–1100% strains), which could monitor both large human motions and subtle motions such as finger knuckle and knee joint motion and wrist pulse beating. These findings indicated that Cel n /PAA-Fe m 3+ hydrogels laid the foundation of developing ultrasensitive and highly stretchable hydrogels holding potential applications in wearable strain sensors, electronic skin, and human–machine interfaces.
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Highly porous nanocellulose aerogels prepared by freeze-drying from various nanofibrillar cellulose (NFC) hydrogels are introduced as nanoparticle reservoirs for oral drug delivery ...systems. Here we show that beclomethasone dipropionate (BDP) nanoparticles coated with amphiphilic hydrophobin proteins can be well integrated into the NFC aerogels. NFCs from four different origins are introduced and compared to microcrystalline cellulose (MCC). The nanocellulose aerogel scaffolds made from red pepper (RC) and MCC release the drug immediately, while bacterial cellulose (BC), quince seed (QC) and TEMPO-oxidized birch cellulose-based (TC) aerogels show sustained drug release. Since the release of the drug is controlled by the structure and interactions between the nanoparticles and the cellulose matrix, modulation of the matrix formers enable a control of the drug release rate. These nanocomposite structures can be very useful in many pharmaceutical nanoparticle applications and open up new possibilities as carriers for controlled drug delivery.
Cellulose separated from corncob was used as a new cellulose resource to produce esterified cellulose nanofiber (E-CNF) with hexanoyl chloride through one-step mechanochemical esterification by ball ...milling. The result showed that corncob cellulose was easily disintegrated and esterified to achevie a high DS, and then, thin nanofiber was compared to the common pulp cellulose resource. The DS of E-CNF was as high as 0.95, and the diameter was about 1.5–2.8 nm. Then, E-CNF was formed to nanopaper by vacuum filtration showing high optical transparency up to 89% at 550 nm. The transparent nanopaper had a Young’s modulus of 5.5 GPa and tensile strength of 110–125 MPa. Due to the introduction of alkyl chain, the wetting property of the nanopaper was changed from hydrophilicity to hydrophobicty. So, it may still work well in a humid environment.
Got a crush: Native cellulose can be dispersed as nanofibers in organic solvents by ball milling with esterification agents. Milling with hexanoyl chloride/DMF gives hexanoyl‐coated nanofibers ...dispersible in several organic solvents. Milling with succinic anhydride/DMSO results water‐dispersible nanofibers. The results open the way to new cellulose mechanochemistries.
