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It is crucial for energy storage devices to manufacture the thick electrode with high energy and power density. The electrochemical performance of the commercial porous carbon supercapacitor electrode fabricated by traditional methods is highly dependent on the electrode thickness. Therefore, a cost-effective method is required to fabricate thick electrode with high mass loading, high specific capacitance and superior rate performance. Herein an ultra-thick cubic electrode is fabricated based on lignin carbon aerogel/nickel (LCAN) bulk with binary network structure using polymerization under ZnCl2 hypersaline condition. This is an efficient and low-cost route to prepare carbon aerogels without drying under rigorous condition and ZnCl2 is an ideal porogen, activating agent and hard template for LCAN. The precise adjustment of ZnCl2/lignin ratio and the combination of LCAN binary network results in the cubic electrode (thickness up to 4.2 mm), with an ultra-high areal capacitance of 26.6 F cm−2 (63% retained from 1 to 200 mA cm−2), an excellent cycle stability even with high mass loading (∼147 mg cm−2) and myriad shapes. These features represent the highest areal capacitance values reported carbonaceous thick electrodes. With these unique features, this study represents a promising 3D thick electrodes for energy-related devices.

Aimed at decreasing the environmental pollution caused by petroleum-derived packing materials, many efforts have been directed towards fabricating biodegradable substitutes, especially of cellulose-based film with functional properties. In this paper, a totally plant-derived antibacterial film was successfully prepared. Regenerated cellulose films were used as substrate and poacic acid, a decarboxylated product from 8–5-diferulic acid, as fungicides. The physical properties and thermal stability of the prepared plant-derived antibacterial films were characterized, and the antibacterial activity was also assessed as the function poacic acid contents. The morphology showed that the cellulose/poacic acid films exhibited a homogeneous and smooth surface and poacic acid was successfully incorporated into cellulose films as revealed by Fourier-transform infrared (FT-IR) spectroscopy and fluorescent microscopy. It was noted that both the tensile strength and thermal stability of the antibacterial films decreased due to the incorporation of the poacic acid. Remarkably, the prepared cellulose/poacic acid films exhibited superior antibacterial activity against Staphylococcus aureus. The notable properties of the cellulose/poacic acid films are promising for applications in food and medical packaging to enhance their safety.

With the rapid development of human society, more and more concerns are directed to utilization of environment-friendly and biodegradable materials. To meet this demand, we fabricated an environment-friendly poly (vinyl alcohol) (PVA)/lignin nanocomposite films with excellent UV-shielding and visible-transparent performance. The lignin-based nanosphere (LNSs) were prepared via self-assembly and uniformly distributed in the PVA matrix by forming strong hydrogen bonds with PVA matrix. With the introduction of LNSs into PVA matrix, the various performance such as tensile strength, thermal stability, and UV-shielding of PVA/Lignin nanocomposite films were enhanced. Amazingly, the UV-shielding results revealed that UVB (320–275 nm) and UVC (275–200 nm) were completely shielded and UVA (400–320 nm) was mostly shielded with addition of 4 wt% LNSs. Meanwhile, the tensile strength of the nanocomposite film was dramatically enhanced, in which the strength increased from 76 MPa to 112 MPa. Since both lignin and PVA were biodegradable materials, this work provides a simple and valuable method for the preparation of biodegradable and functional films.

Facile and controllable synthesis of graphene or graphene-like 2D nanosheets from plentiful and biocompatible materials still remains a great challenge. Herein, a bottom-up and controllable approach was firstly reported to transform earth-abundant lignosulfonate into graphene-like materials, in which lignosulfonate-based 2D nanosheets were fabricated via self-assembly in water/acetone dual solvent system, and then the nanosheets materials were transformed into graphene-like materials by carbonization. The physical properties of obtained lignosulfonate-based nanosheets were characterized, and the formation mechanism of these nanosheets was also elucidated. The thickness of the nanosheets was in the range of 5–20 nm depending on the concentration of lignosulfonate in water. Directed by π − π interactions and hydrogen bonds, the evolution of layered nanosheets seemed to experience from nano-sized rodlikes, a flake with defect holes, and smooth lignosulfonate-based nanosheets. Because of the relatively lower resistance, nano-sized structures and good cytocompatibility, the lignosulfonate-based graphene-like materials exhibited great potential in biomedical energy-related applications.

Inspired by the hierarchical structure of natural nacre, a binary artificial nacre with excellent mechanical performance, tensile strength and toughness was successfully constructed based on water-soluble cellulose acetate (WSCA) and reduced graphene oxide (rGO). The tensile strength and toughness of the hybrid films were markedly improved by the introduction of rGO, and the tensile strength and toughness of the rGO/WSCA composite films reached 499.3 MPa and 9.6 MJ/m3 (rGO-WSCA-III), respectively, which are approximately 5.0 and 5.3 times that of natural nacre. In addition, the hybrid rGO/WSCA films showed better flame retardancy and stability in water, and high electrical conductivity. In this study, we provide a strategy to design and fabricate exceptionally strong and tough artificial nacre, which has potential application in tissue engineering and as a humidity sensor.

Synthesis of polymeric hollow spheres with porous structures has attracted significant attention in material applications. In the present work, without requiring any template and core removal, hollow spheres with tunable porous structures from amphiphilic lignin polymers were synthesized by directing the different length of hydrophobic alkyl chains. Remarkably, the results from scanning electron microscope (SEM) showed that lignin hollow sphere possessed only one hole by acetylation, while it became porous structures with the increase of alkyl chain length by acylation of propionylation, butyrylation and valerylation. Amazingly, all the LHSs exhibited strong emission peaks in visible spectral range as excitated with wavelength from 260 to 340 nm. In addition, as revealed by SEM and transmission electron microscope (TEM) images, the formation mechanism for the porous hollow spheres was proposed. The presence of hydrophobic and π–π interactions between the aromatic groups resulted in the lignin molecules gathering mutually to form the bilayers (nanosheets) with some imperfection sites. Then, the 2D patches intended to reduce their total energy via curling, which favored the formation of initial sphere structures, and other 2D patches kept continuously stacking on the surface of spheres, resulting in formation of porous lignin hollow spheres. Our study established a new method for fabricating porous hollow spheres from amphiphilic lignin polymers.

In this paper, a novel way for high value-added application of lignosulfonate is presented. In this study, we use lignosulfonate nanosheets to fabricate a free-standing, binder-free, ultrathin and light-weight conductive film electrode via vacuum filtration method. The results show that LS is a promising candidate material for the preparation of electrochemical capacitor film electrode. It is worth mentioning that we use non-toxic, pollution-free aqueous solution (water) over organic solvents as the dispersion during the reductive graphene oxide (RGO) preparation process. The electrochemical measurements exhibit that the resistivity of lignosulfonate nanosheets/RGO (LNRGO) film electrode is 0.66 × 10−3 kΩ cm−1. The specific capacitance of the LNRGO film electrode is calculated to be 120 mF cm−2 at the current density of 0.2 mA cm−2, which is approximately 6.67 times larger than that of RGO-water film electrode.

The applications of cellulose are increasing rapidly attributing to their biodegradability and renewability. However, most of these cellulose-based materials possess poor mechanical performance, which restrict their advanced applications. In this study, a facile method was applied to fabricate composite paper with excellent mechanical and barrier properties via simple coating dissolved cellulose in ionic liquid. Subsequently, the surface wettability, oxygen permeability and mechanical properties of the resulting composites were investigated. Remarkable, both the dry and wet tensile strength of the composite papers was dramatically increased up to 101 and 14.17 MPa, which was greater than controlled paper (63.98 and 1.15 MPa). Moreover, with only 2% weight loading of regenerated cellulose, million times decline of oxygen permeability coefficient was obtained. Though the composite papers showed enhanced hydrophilicity, it exhibited strong water-resistant and shape-retaining properties in water. Therefore, the resultant composite papers showed great potential in packaging application with higher humidity.

Here, we reported a facile strategy to create superhydrophobic aerogels via freeze-drying of silylated cellulose nanofibers and silica nanoparticles mixed suspensions. The as-prepared aerogels possessed a hierarchical porous structure with high roughness and low surface energy. The hierarchical rough structure and low surface energy endowed the resultant aerogels with superhydrophobicity (water contact angle up to 168.4°). Importantly, the composite aerogels could separate surfactant-stabilized water-in-oil emulsions without external pressure, with high separation efficiency (>99%) and high flux (1910 ± 60 L m–2 h–1). The aerogels were easily recyclable and showed great antifouling performance, which could meet the requirements for long-term use. We also assembled a simple device to collect oil directly from water-in-oil emulsions with the obtained aerogel and a self-priming pump. The fabrication of the composite aerogels in our work provides a versatile way to fabricate cellulose composite materials for ...

The possibility and feasibility of nanocrystalline cellulose (NCC) for dispersing hydrophobic graphene in aqueous solutions were studied in the present work. The dispersion properties of graphene particles in aqueous media as a function of various amounts of NCC were investigated. The rheological behavior of NCC-dispersed graphene suspensions was studied, and a polynomial model was proposed and employed to simulate the obtained shear flow of graphene suspensions. The results of UV–Vis analysis and sedimentation test suggested that the increased NCC addition significantly led to the improved dispersion properties of graphene suspensions. Rheological behavior measurements demonstrated that graphene suspensions exhibited a reduction trend in the shear viscosity, shear stress, and viscoelasticity with the increased amount of NCC addition. Meanwhile, the shear viscosity and shear stress of graphene suspensions were found to show a dependency on the process temperature. The above results supported the conclusion that NCC is a promising candidate for improving the dispersion and flowability of graphene in aqueous media.

Hemicellulose-based composites have become promising candidates for eco-friendly packaging applications because of their biodegradability and cost-effectiveness. However, the inherently poor mechanical properties of hemicellulose-based composites largely hinder their potential for targeted application. Fortunately, nanocrystalline cellulose (NCC), an eye-catching nanomaterial, may offer opportunities for addressing the above issue due to its outstanding mechanical properties and environmental friendliness. Herein, a comparative study was conducted on the effect of unmodified and cationically modified nanocrystalline cellulose (CNCC) on the overall properties of the as-prepared hemicelluloses (HC)/sorbitol (SB) films. Scanning electron microscopy (SEM) image shows that the addition of CNCC imparted a relatively smooth surface to the obtained HC/SB films in comparison to NCC. Furthermore, CNCC reinforced HC/SB films exhibited improved thermal stability as compared to that with NCC. From rheological behavior evaluation, the presence of NCC, particularly CNCC, had an important effect on thickening HC/SB suspensions. The tensile stress of the composite films with 9% NCC and 9% CNCC was 9.18 and 10.44 MPa, respectively, which was increased by 14 and 30% in comparison to that of pure HC/SB film (8.05 MPa). The marked increase in elastic modulus as a function of the added NCC or CNCC was also identified. This result strongly supports the conclusion that the addition of NCC or CNCC was effective in improving the mechanical properties of HC/SB films.

In this article, a simple strategy was employed to fabricate bioinspired hybrid composite with carboxymethyl cellulose (CMC), graphene oxide, and reduced graphene oxide/alumina (rGO/Al) by a facile solution casting method. The tensile strength and toughness of rGO/Al-CMC-GO can reach 586.6 ± 12 MPa, 12.1 ± 0.44 MJm–3, respectively, due to the interface strengthening of alumina, which is 1.43 and 12 times higher than steel and about 4.3 and 6.7 times that of nature nacre. The artificial nacre hybrid composite is conductive due to the introduction of rGO/Al on the surface. Interestingly this structure can also be coated on the surface of cotton thread to give the thread good mechanical performance and conductivity. Additionally, the artificial nacre has better fire shielding and gas barrier properties. The oxygen permeability (OP) for 1% rGO/Al-CMC decreased from 0.0265 to 0.003 mLμm m–2 day–1 kpa–1, the water vapor permeability (WVP) decreased from 0.363 to 0.205 gmmm–2 day–1 kpa–1 when the concentration i...

Facile synthesis of carbon quantum dots with high fluorescence and excellent biocompatibility from plentiful and biocompatible materials still attracts much attention because of their great potential value in sensors and imaging. In this study, a highly fluorescent and super biocompatible N-doped carbon quantum dots derived from green precursor of aminated alkali lignin has been synthesized for cellular imaging. The amine-rich lignin carbon quantum dots (AL-CQDs) was firstly synthesized by introduction of secondary amine groups into lignin backbones via both Mannich and Machael addition reaction. The resulted AL-CQDs within the range of 4–10 nm exhibited excitation-dependent and pH-stable fluorescence properties and was employed for the detection of irons with a wide range from 100 nM to 1 mM and a low detection limit of 8 nM, in which the Fe3+ ions could be captured by the amine groups of the AL-CQDs to form an absorbent complex, resulting in a significant fluorescence quenching. Meanwhile, the AL-CQDs were successfully applied to cell imaging and intracellular irons detection benefited from low cytotoxicity and good biocompatibility. This work would shed much light on converting agricultural waste into bio-based nanomaterials and their potential applications.

In the shaking table tests of underground structures, the scale ratios of the soil and structure are inconsistent. To this end, a scaled model soil was developed in this study. Through a series of tests, the dynamic response of the model soil was investigated. A clay mixed with sawdust was designed for shaking table tests based on the predominant period similarity relationship between the structure and the foundation soil. The sawdust-mixed clay was subjected to a series of shaking table tests at Beijing University of Technology using a rigid prefabricated continuous model box (dimensions: 7.7 m × 3.2 m × 1.2 m). Through the tests, the performance of the model box and the nonlinear seismic behavior of the model soil were studied. The results are as follows: (i) The boundary effect of the model box was negligible during the test. (ii) The predominant frequencies of the model soil shifted toward lower values with increasing shaking intensity. This indicated that the model soil became increasingly softer and that the nonlinear effect of the soil was more evident. (iii) With the increase in the shaking intensity, the peak acceleration of the model soil at the same measured points increased, whereas their amplification factors decreased. In addition, the amplification factors first decreased and then increased from the bottom to the top of the soil. This might have been due to the increase in the shear strain and decrease in the shear modulus of the soil with increasing shaking intensity. (iv) The shear modulus of the soil was closely related to the confining pressure. At the same shaking intensity, the shear stress increased, and the shear strain decreased from top to bottom of the model soil.

Two-dimensional transition metal carbides (MXenes) have shown extraordinary potential in energy storage device, especially in supercapacitors. However, the major drawbacks of these eletrode materials are the re-stacking problem and the narrow operating potential range, which limit them to reach high energy density. The P-π conjugate structure of lignosulfonate (LS) endows α and β carbon a strong chemical reactivity and local positive potential, which can modify the surface of MXene and avoid the re-stacking problem. Herein, for the first time, the LS modified-MXene (Ti3C2Tx)-reduced graphene oxide (rGO) 3D porous (MLSG) aerogel is synthesized. The MLSG-6 aerogel exhibits more excellent electrochemical performance when compared to pure MXene even with the high mass-loading of 5.1 mg cm−2. As a supercapacitor electrode, the MLSG-6 aerogel exhibits high specific capacitance of 386F g−1 and 1967 mF cm−2 at scan of 2 mV s−1, and excellent rate performance with the capacitance of 241F g−1 at scan of 100 mV s−1. Moreover, utilizing redox pseudocapacitive characteristics of LS under positive potential, the 3D porous LS-functionalized reduced graphene oxide (LSG) aerogel is reported to match with MLSG aerogel to construct an all-pseudocapacitive asymmetric supercapacitor with potential range of 1.45 V. Consequently, the asymmetric supercapacitor can deliver an energy density of 142 µW h cm−2 at power density of 4900 μW cm−2, with 96.3% capacitance retention after 10,000 charge–discharge cycles. This work realizes the dual utilization of high chemical reactivity and pseudocapacitance characteristics of LS to the negative and positive electrodes of the asymmetric supercapacitor.

Lignin, a byproduct of the wood-pulping industry, is mostly treated as a noncommercialized waste product. Therefore, it is significant to study its potential for the conversion of this renewable and sustainable resource into high-valued chemicals and materials. In this study, a renewable lignin-based material with high performance in wastewater treatment has been explored on account of its satisfactory properties and being environmentally friendly. Herein, lignin hollow microspheres (LHM) were facilely prepared from esterified organosolv lignin with maleic anhydride (MA) via self-assembly in the mixed tetrahydrofuran–Fe3O4 nanoparticles aqueous media. Moreover, the magnetic lignin spheres (MLS) were also successfully fabricated by introducing Fe3O4 nanoparticles. The structural changes of esterified lignin polymers were identified and morphology and property of obtained LHM and MLS were characterized by means of TEM, SEM, VSM and FT-IR. In addition, the adsorption capacities of MLS for methylene blue and ...

Interpenetrating polymer network (IPN) hydrogels were developed by engineering ionic bridges between carboxylated cellulose nanofibrils (CNFs) and amine-terminated poly(ethylene glycol) (PEG) into a covalent poly(acrylamide) architecture network, and the role of precoordinated CNF–PEG dynamic complexes in the IPN hydrogels viscoelastic dynamics was explored. The results shown that the ionic complexes significantly improved the IPN hydrogels energy dissipation and elastic recovery properties, leading to strain-rate dependent mechanics and notable enhancement in tensile toughness. The uniaxial deformation over a range of strain rates demonstrated that fracture energy peaked at 0.05 s–1 before decreased with further increasing strain rate, consistent with the crack propagation rate result. This straightforward sacrificial bonding strategy validates the hypothesis that elastomers with high toughness and excellent recovery can be achieved by incorporating precoordinated supramolecular associating motifs, which...

This paper presents a scheme of double-plane shear testing to investigate the shear transmission mechanism of strain-hardening cementitious composite (SHCC) after crack opening; the focus is on the shear stress transfer behaviour on the crack surface of the SHCC, contributed by both the contact effect of the matrix and the fibre bridging effect on the crack surface. The experimental results demonstrate that the transferred shear stress on the crack surface of the SHCC is contributed by both the contact effect of the matrix and the fibre bridging effect on the crack surface until peak shear stress, whereas after the separation of the crack surfaces, it is influenced solely by the fibre bridging effect. It is confirmed that the fibre bridging effect on the crack surface of SHCC has considerable influence in the shear fracture behaviour of SHCC.

This paper presents an investigation of the feasibility of self-piercing rivet (SPR) technology for use in cold-formed steel (CFS) structures. The mechanical properties of the joints, floor trusses and prefabricated CFS composite floor modules connected by SPR and self-drilling screws (SDSs) were compared. The failure mode, bearing capacity, stiffness, ductility, ultimate deformation and other performance of CFS specimens connected with SDS and SPR were analyzed. Considering the construction method of CFS structure and the particularity of SPR connection technology, the construction feasibility of SPR connection was analyzed. The results showed that under the same condition, the stiffness and ductility of the SPR joint specimens are significantly better than those of the SDS joint specimens, the bearing capacity of the two are similar, and the ultimate mid-span deflection of the composite floor with SPR specimens is significantly greater than that with SDS specimens. It is highly feasible to use the SPR connection instead of the SDS connection for prefabricated light steel floor system with high stiffness requirements

During recent years the use of smart colorimetric packaging films for monitoring food freshness has received widespread attention. However, their poor mechanical strength and hydrophilic properties are the major problems hindering the large-scale application. Here, we employed biodegradable cellulose and naphthoquinone dyes extracted from Arnebia euchroma (AENDs) to fabricate a novel colorimetric sensing film with high tensile strength of 227 MPa and hydrophobic properties (water contact angle of 112.2°) for real-time monitoring of the freshness of shrimp and pork. In addition, the effectiveness of the sensing film in detecting the freshness of shrimp and pork under 20 °C, 4 °C and-20 °C conditions was confirmed by measuring the total volatile basic nitrogen (TVBN) and total viable count (TVC). Visual observation confirmed that the sensing film clearly changed from rose-red to purple, then to bluish violet providing a good indication of spoilage, which correlated well with TVBN and TVC content in shrimp and pork measures by standard lab procedures. The colorimetric sensing film developed here would be promising in fabricating high mechanical strength and hydrophobic properties smart labels for visual monitoring the freshness of shrimp and pork.

To improve the operational reliability of renewable energy conversion system, high-performance polymers and engineering plastics are used to make some parts and components of the energy conversion device, especially in the marine renewable energy generation field. In this article, special plastic bearings based on the material of polyoxymethylene (POM) were designed and applied in the power generation device of both tidal current energy and island wind energy. The properties of POM were analyzed, and the load of a POM ball was tested. Special structures of the plastic bearings were designed to meet the requirements of pressure resistance and to reduce the friction. These plastic bearings had been used in the prototypes of 20 kW tidal current turbine generation device and 15 kW island wind turbine generation device. According to the prototypes’ operation, the results indicate that these plastic bearings work well and are very suitable for the application in renewable energy conversion system. By optimizing the structure, such plastic bearings would be generalized and applied in the renewable energy generation device with a higher power level.

The biologically inspired dynamic materials offer principles for designing man-made systems by using assembly approach. In this work, the hybrid hydrogels consist of cellulose nanofibrils (CNFs) that combine a mechanically strong skeleton with flexible PEG chains. The distinct gel state is observed at room temperature with G′ > G″ and an order of magnitude higher G′ values from 0.08 to 0.93 kPa upon increasing CNF concentration from 0.2 to 2 wt % at constant 2 wt % PEG. Combined with mechanically strong CNFs and dynamic ionic bridges through amine-terminated tetra-arm PEG adsorption to TEMPO-oxidized colloidal nanofibrils surface, the assembled colloidal hydrogels show high modulus, reversible gel–sol transition, and rapid self-recovery properties. It is envisioned that simply mixing hard CNF and soft polymeric matrix would lead to a facile method to bridge reversible dynamic bonds in a cellulose-based hybrid network and broad cellulose applications in the preparation of high performance supramolecular sy...

This paper presented a experimental investigation into the advantage of RC member with shear strengthening using strain hardening cementitious composites (SHCC), focused on the crack pattern of SHCC strengthening layer and its obvious advantage for increasing the shear load carrying capacity of the strengthened RC member. Especially, the shear failed SHCC member was also adopted to reflect the reduced multiple fine crack distribution in SHCC strengthening layer. Moreover, the contributions of matrix and reinforcing fiber for shear load carrying capacity of SHCC strengthening layer were also calibrated respectively, and the shear load carrying capacity of SHCC strengthening layer was assumed as the sum of load carried by matrix and reinforcing fiber. This work provided experimental foundations for RC member with shear strengthening using SHCC.

The incorporation of nanoparticles into polymer represents a fundamental pathway in the development of reinforced composites. Inspired by rigid cellulose nanocrystals (CNCs), a simple and robust approach for the fabrication of tough and stretchable hydrogels was proposed that based on the incorporation of a three-dimensional CNC template. By mimicking the hierarchical cork structure, the obtained composite hydrogels with a binary network can sustain structural integrity under a load of 12 000-time of the template weight and recover from >85% tensile compression. Analysis of toughening mechanisms reveals two strategies, template pullout and polymer chain sacrificial bonds, that synergistically corroborate the materials integrity to large deformations. First, the embedded CNC template splayed among neighboring fibrils and bridged crack continuously, which entailed the efficient energy dissipation via strong hydrogen interactions between packed CNC walls without comprising the template integrity. Second, the...

The purpose of this article was to explore the influences of alkalis types on the cellulose/Mn3O4 composites via a sonochemistry method. In this study, cellulose/Mn3O4 composites were successfully fabricated using four types of alkalis (urea (CO(NH2)2), hexamethylenetetramine ((CH2)6N4, HMT), NaOH, and KOH) by an environmentally-friendly sonochemistry method. The phase, shape, thermal stability, and the formation mechanism of the cellulose composites were researched in detail. Experimental results demonstrated that the types of alkalis played an important role in the phase, shape, dispersion, and thermal stability of cellulose/Mn3O4 composites. By thermal treatment of cellulose/Mn3O4 composites at 600 °C for 3 h in air, the Mn3O4 crystals were obtained. This novel method reported here maybe has a guiding significance for the synthesis of manganese oxide materials and other metal oxides using cellulose as template.

Water-soluble cellulose acetate (WSCA), one of the most important cellulose derivatives, possesses biocompatibility, biodegradability and broad chemical modifying capacities. In this work, highly polymerized WSCA was firstly synthesized and used as cross-linker to fabricate highly ductile, tough and resilient WSCA/polyacrylamide (PAM) composite hydrogels. The results showed that the WSCA/PAM nanocomposite hydrogels exhibited extraordinary toughness and ductility with a tensile strength of 297 kPa and elongation at break of about 4020%. The enhancement of mechanical properties and stretchability were due to the synergistic effect from the hydrogen bonding and physical entanglement between the composite matrixes. Under stretching conditions, hydrogen bonds and the dense entanglement between WSCA chains and PAM could dynamically break and rearrange to dissipate energy. At the same time, the filaments of PAM embedded in layered WSCA matrix became unfolded or fractured to dissipate energy and maintained the conformation of hydrogels. It was envisioned that the introduction of WSCA into polymeric matrix would generate a facile method to fabricate multiple layered hybrid hydrogel network and significantly widen the WSCA applications in the preparation of high performance supramolecular systems.

The synthesis platform of composite hydrogels containing rigid reinforcing filler cellulose nanocrystals (CNCs) and polymer matrix polyacrylamide (PAM) has been proposed (Yang et al. in Cellulose 20:227–237, 2013). The features of CNCs as multifunctional crosslinkers and flexible polymer chain entanglements contributed to the unique arrangement of CNC/PAM clusters with reversible network structures. In this article, the chemical crosslinking agent N,N′-methylene-bisacrylamide (BIS) was added to obtain the dual crosslinked networks, and the mechanical properties of the resulting co-crosslinked hydrogels were examined by tailoring the CNC and BIS concentrations. The results indicated that the homogeneous dispersion of CNCs throughout the polymer matrix was disturbed in the presence of BIS, and the covalent crosslinkers led to weakness and brittleness of the hydrogels. Some new entanglements within the networks were formed after a simple drying treatment, which was verified by the greater tensile strength compared with the as-prepared ones. The mechanism for the formation of these new entanglements was ascribed to the irreversible rearrangement of the CNC/PAM network structure, whereas for co-crosslinked hydrogels no strength increment was observed after the drying treatment.

Nanocomposites have drawn a great interest in materials science of elastomers in recent years, and tailoring interfacial interactions between fillers and polymer matrix plays a critical role in improving their mechanical properties. The synthetic platform of tough and stretchable cellulose nanocrystal–poly(acrylamide) (CNC–PAM) composite hydrogels was proposed and applied here to unravel the role of covalent network in PAM and physical interactions by CNC surface adsorption. The attractive physical interactions in the network were considered to increase the fracture strength of the hydrogels via reversible adsorption–desorption processes on the CNC surface. Stress-sensitive characteristic shifts of the Raman peak located at 1095 cm–1 indicated an efficient load transfer across the interface, where the tensile modulus was higher than the compression modulus. In situ transmission electron microscopy observation allowed to demystify the composites deformation process and interfacial bridging between CNC and ...

Position-configurable, reproducible, vertically aligned nanosheets assemblies (ANAs) arrays are fabricated by polymer-templated electrodeposition method at room temperature. Here, nanoimprint lithography is utilized to fabricate polymer template on the fluorine-doped tin oxide substrate for the purpose of evenly tuning the location of Ag nanostructures. Subsequently, vertically aligned ANAs can be achieved at the bottom of each hole via electrodeposition in a mixed aqueous solution of AgNO3 and citric acid. To obtain uniform ANAs array, we have systematically investigated the factors that influenced the electrodeposition. It was found that the formation of uniform ANAs arrays is strongly depended on the seeding layer, citric acid concentration, electrodeposition potential and time. The as-synthesized ANAs array exhibited a remarkable SERS activity and Raman signal reproducibility to rhodamine 6G, a concentration down to 10(-13) M can be identified. Our results revealed that the ANAs array is a highly desirable candidate as the reliable enhancer for high performance SERS analysis.

Novel hydrogels were prepared from hemicelluloses, polyvinyl alcohol (PVA), and chitin nanowhiskers through 0, 1, 3, 5, 7, and 9 times of freeze/thaw cycle. These hydrogels were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), swelling property, and compressive strength. The repeated freeze/thaw cycles induced physically crosslinked chains packing among these polymers, and a phase separation caused by the hydrogen bonds. Larger pores led to a high swelling degree, whereas the formation of compact structure after multiple freeze/thaw cycles resulted in high mechanical strength and thermal stability. The highest compressive strength of these hydrogels was achieved by the 9 times of freeze/thaw cycles with compressive stress of 10.5 MPa. This work provides a remarkable way for the preparation of hydrogels with good mechanical properties by physical method.

Cellulose aliphatic esters (CEs) are important cellulose derivatives that have been widely used in many fields such as plastics, textiles, membranes, etc. However, in traditional methods, long pretreatment and reaction times limit the manufacture of CEs and their widespread application. Herein, a very efficient method for the preparation of CEs in a heterogeneous system was developed. This method involved the transesterification of cellulose with vinyl esters (from C4 to C14) in dimethylsulfoxide under the catalysis of aqueous NaOH. For better understanding of this new reaction system, factors such as the water content, amount of catalyst, reaction temperature and molar ratio of vinyl acetate to the anhydroglucose unit were explored. Results obtained from FT-IR, 1H and 13C NMR spectroscopies confirmed that CEs could be synthesized at 100 °C within 5 min. High water content or excessive amounts of NaOH were detrimental to the synthesis of CEs. Results from small-angle X-ray diffraction showed that the interplanar spacings of these CEs showed an increasing trend with the length of the aliphatic chain. Thermogravimetric analysis and derivative thermogravimetric analysis showed that CEs had higher thermal stability than cellulose. This work provides a new and highly efficient method to synthesize various CEs.

In this study, environmentally friendly regenerated cellulose films with enhanced tensile strength were successfully prepared by incorporation of plasticizer agents using 1-ethyl-3-methylimidazolium acetate as solvent. The results of morphology from scanning electron microscopy and atomic force microscopy showed that cellulose films possessed homogeneously, and exhibited smooth structure. 13C CP/MAS NMR spectra showed that the regenerated cellulose films were transferred from cellulose I to cellulose II. Moreover, the incorporation of plasticizer agents, especially in the presence of glycerol, significantly improved the tensile strength of cellulose film (143 MPa) as compared to the controlled sample. The notable properties of the regenerated cellulose films are promising for applications in transparent packaging.

Nanoimprint lithography (NIL), as a promising next generation lithography method, has the advantages of high throughput, sub-10-nm feature and low cost. However, the requirements, such as the structure with high aspect ratio, large area uniformity, and pattern transfer on nonflat surface, have barely been satisfied at the same time. In this study, the authors present a novel fabrication process by introducing a three-mask-layer (TML) Soft UV NIL technique which proves to be a simple and effective method. The initial mold with low aspect ratio can guarantee the imprint uniformity on large area under a high pressure in NIL. Meanwhile, high aspect ratio structure can be easily obtained due to a high etching selectivity of SiO2 to resist in O2 plasma dry etching. Using the proposed technique to fabricate 40 nm gratings with the aspect ratio as high as 6 is proved successful. Uniform photonic crystal (PC) structures with micrometer scale nonflat steps are obtained on large area. The photoluminescence enhancements of the PC light-emitting diode (LED) fabricated by the proposed method to the one with conventional process and un-patterned LED are 1.6 fold and 2.2 fold, respectively.

The unique combinations of hard and soft components with core/shell structures were proposed to synthesize high strength nanocomposite hydrogels. The elastomeric hydrogels containing rod-like cellulose nanocrystals (CNCs) core and polyacrylamide shell were made from aqueous solutions via free radical polymerization in the absence of chemical cross-links. The obtained hydrogels possessed greater tensile strength and elongation ratio when compared with chemically cross-linked counterparts. Oscillatory shear experiments indicated that CNCs interacted with polymer matrix via both chemical and physical interactions and contributed to the rubbery elasticity of the hydrogels. The nanocomposite hydrogels were more viscous than the chemical hydrogels, suggesting the addition of CNC led to the increase of energy dissipating and viscoelastic properties. The network structure model was proposed and it suggested that the high extensibilities and fracture stresses were related to the well-defined network structures with low cross-linking density and lack of noncovalent interactions among polymer chains, which may promote the rearrangements of network structure at high deformations.

The poor mechanical strength of traditional synthesized hydrogels remains the greatest challenge to their performance as tissue engineering materials. Unique combinations of hard and soft components were used to design and synthesize elastomeric nanocomposite hydrogels with a core–shell microstructure. The nanocomposite hydrogels consisting of multifunctional cross-links of silica nanoparticles (SNPs) as the nucleus and poly(acrylamide) (PAM) as the shell were prepared by mixing both components in solution, and photo-crosslinking by UV radiation. Transmission electron microscopy (TEM) observations confirmed the existence of a core–shell morphology, and dynamic light scatting (DLS) measurements were applied to monitor the particle conformation changes near the critical gelation condition. The results indicated that the concentration of the core significantly affected the mechanical properties of the hydrogel and the unique three-stage arrangement process exhibited an average effective functionality around 28. The molecular weight of grafted polymer chains was monitored and it was found that the grafted PAM chain had a high value of 2.46 × 105 g mol−1, and it remained almost constant when the SNP concentration (CSNP) exceeded the critical value. The mechanical behavior of the nanocomposite hydrogels was studied with elongation under large strains and it was found that the hydrogels exhibited excellent tensile properties, including a modulus 9–38 kPa, a fracture strain 700–1000%, and a fracture stress 80–250 kPa, depending on the SNP concentrations. Stress relaxation experiments indicated that the nanocomposite hydrogels were more viscous than comparable chemical gels and were more efficient at the energy dissipation process, which is related to the orientation of SNPs and relaxation of the PAM chains. Further development of the synthetic platform would potentially lead to valuable knowledge for the design of high performance hydrogels in biomedical and pharmaceutical applications.

Biomass is the most plentiful and well-utilized renewable carbon resource on the earth. Direct conversion of biomass to carbon aerogel provides a promising approach to develop adsorbent materials. In the present work, the effect of presence of water during hydrothermal treatment and holding temperature during post-pyrolysis process have been investigated for the preparation of carbon aerogels (CAs) using eggplant as raw material. The results showed that the addition of water during hydrothermal treatment was advantageous for the preparation of CA samples with higher surface area and stronger hydrophobicity, resulting in superior adsorption capacities of CAs for both oil and organic solvents compared with that fabricated without the presence of water. The optimized carbon aerogel possessed higher specific surface of 249 m2·g−1 and exhibited excellent hydrophobicity with a water contact angle of 133°. The adsorption capacities of carbon aerogel for oils and organic solvents could reach 35–45 times its own weight. In addition, the adsorbed oil and organic solvents could be recovered by distillation, and the regenerated carbon aerogels samples exhibited the stable performance and outstanding reusability. Therefore, the carbon aerogel has great potential in application of oil recovery and environmental protection.

In this paper, we report a facile, rapid, and green strategy for the synthesis of cellulose/hydroxyapatite (HA) nanocomposites using an inorganic phosphorus source (sodium dihydrogen phosphate dihydrate (NaH(2)PO(4)2H(2)O)), or organic phosphorus sources (adenosine 5-triphosphate disodium salt (ATP), creatine phosphate disodium salt tetrahydrate (CP), or D-fructose 1,6-bisphosphate trisodium salt octahydrate (FBP)) through the microwave-assisted hydrothermal method. The effects of the phosphorus sources, heating time, and heating temperature on the phase, size, and morphology of the products were systematically investigated. The experimental results revealed that the phosphate sources played a critical role on the phase, size, and morphology of the minerals in the nanocomposites. For example, the pure HA was obtained by using NaH(2)PO(4)2H(2)O as phosphorus source, while all the ATP, CP, and FBP led to the byproduct, calcite. The HA nanostructures with various morphologies (including nanorods, pseudo-cubic, pseudo-spherical, and nano-spherical particles) were obtained by varying the phosphorus sources or adjusting the reaction parameters. In addition, this strategy is surfactant-free, avoiding the post-treatment procedure and cost for the surfactant removal from the product. We believe that this work can be a guidance for the green synthesis of cellulose/HA nanocomposites in the future.

Carbon dots (CDs) as a new series of fluorescent nanomaterials have drawn great attention in recent years owning to their unique properties. In this paper, a simple carbonization approach to synthesize amino-functionalized CDs was developed by using chitosan as the carbon precursor. The as-prepared CDs possessed desirable amino function group on their surface and exhibited bright luminescence with absolute quantum yield (QY) of 4.34%, excitation-, pH-dependent and up-conversion fluorescence behaviors. Furthermore, we have investigated the cytotoxicity and biocompatibility of the as-prepared CDs, which demonstrated that the as-prepared CDs have the potential applications in biosensing, cellular imaging and drug delivery.

The fabrication of reusable and biodegradation materials from renewable resources such as cellulose is essential for a sustainable world. The core-shell structured CdS-decorated TiO2/Carbon microspheres (CdS/TiO2/Carbon MS) photocatalyst was synthesized with controlled hydrolysis and a novel sonochemical method. It was prepared by using crosslinked microcrystalline cellulose as the core, tetrabutyl titanate as the titania source and CdS as the photosensitizer. The morphology, chemical structure and properties of the obtained material were characterized by many means. Additionally, the photocatalytic activity of the CdS/TiO2/Carbon MS was evaluated by the photodegradation efficiency of Rhodamine B solution, which reached 95.24% under visible light irradiation. This study demonstrated the excellent photocatalytic performance of CdS/TiO2/Carbon MS, which might have promising applications in environmental treatments.

Recent Advances in Cellulose-Based Materials : Synthesis, Characterization, and Their Applications

The purpose of this study is to investigate the fabrication of wood powder/CaCO 3 composites. In this study, we report a hydrothermal route for the preparation of wood powder/CaCO 3 composites using the dewaxed wood powder. The wood powder was pretreated by the NaOH/urea solution. The urea acts as the CO 3 2− source and provides a basic condition for the synthesis of CaCO 3 . The influences of several reaction parameters such as the heating time and the types of additives on the products were investigated by X-ray powder diffraction, Fourier transform infrared spectrometry, scanning electron microscopy, thermogravimetric analysis, and differential thermal analysis. The experimental results demonstrated that the additives not only had an effect on the phases of composites, but also on the microstructure and shape of composites. Moreover, the thermal stability of the samples was also investigated. Compared with cellulose-based composites, the wood powder composites can utilize all the main components of lignocelluloses.

Carbon quantum dots (CQDs) as a rising star of carbon nanomaterials have extensive applications due to their excellent characteristics. In this work, we introduce a simple and green method to prepare nitrogen-doped lignin carbon quantum dots (N-L-CQDs) by using alkali lignin carbon sources and deep eutectic solvent (DES) as solution and nitrogen source. The physiochemical characterization results suggested that N-L-CQDs with diameters ranging from 4 to 12 nm were successfully synthesized. The optical properties data indicated that the as-prepared N-L-CQDs with a quantum yield of 7.95% exhibited excellent optoelectronic properties, excitation-dependent and pH stability. After that, we have investigated the N-L-CQDs used as fluorescent probes to detect iron ions, which suggested that the as-prepared N-L-CQDs exhibited excellent sensitivity and selectivity for Fe3+ with a detection limit of 0.44 &mu, M. Besides, cytotoxicity of N-L-CQDs was also evaluated by MTT assay. These results demonstrated that the as-prepared N-L-CQDs with excellent properties have potential applications in environment and biomedicine.

With the serious “white pollution” resulted from the non-biodegradable plastic films, considerable attention has been directed toward the development of renewable and biodegradable cellulose-based film materials as substitutes of petroleum-derived materials. In this study, environmentally friendly cellulose films were successfully prepared using different celluloses (pine, cotton, bamboo, MCC) as raw materials and ionic liquid 1-ethyl-3-methylimidazolium acetate as a solvent. The SEM and AFM indicated that all cellulose films displayed a homogeneous and smooth surface. In addition, the FT-IR and XRD analysis showed the transition from cellulose I to II was occurred after the dissolution and regeneration process. Furthermore, the cellulose films prepared by cotton linters and pine possessed the most excellent thermal stability and mechanical properties, which were suggested by the highest onset temperature (285 °C) and tensile stress (120 MPa), respectively. Their excellent properties of regenerated cellulose films are promising for applications in food packaging and medical materials.

The demand for substitution of fossil-based materials by renewable bio-based materials is increasing with the fossil resources reduction and its negative impacts on the environment. In this study, environmentally friendly regenerated cellulose films were successfully prepared using 1-allyl-3-methylimidazolium chloride (AmimCl), 1-butyl-3-methylimidazolium chloride (BmimCl), 1-ethyl-3-methylimidazolium chloride (EmimCl), and 1-ethyl-3-methylimidazolium acetate (EmimAc) as solvents, respectively. The results of morphology from scanning electron microscopy (SEM) and atomic force microscopy (AFM) showed that all the cellulose films possessed smooth, highly uniform, and dense surface. The solid-state cross-polarization/magic angle spinning (CP/MAS)13C NMR spectra and X-ray diffraction (XRD) corroborated that the transition from cellulose I to II had occurred after preparation. Moreover, it was shown that the ionic liquid EmimAc possessed much stronger dissolubility for cellulose as compared with other ionic liquids and the cellulose film regenerated from EmimCl exhibited the most excellent tensile strength (119 Mpa). The notable properties of regenerated cellulose films are promising for applications in transparent biodegradable packaging and agricultural purpose as a substitute for PP and PE.

Epoxidized soybean oil (ESO), which is a biomass-derived resource, was first used as a novel plasticizer for ethyl cellulose (EC) film preparation. Surface morphologies, mechanical performances, thermal properties, oxygen and water vapor permeabilities of plasticized EC films were detected in detail to evaluate the plasticizing effect of ESO and explore the plastication mechanisms. Results showed that ESO was an effective plasticizer that outstripped conventional plasticizers, i.e. dibutyl phthalate (DBP) and triethyl citrate (TEC) in producing high-quality films. Especially, at plasticizer concentrations of 15–25%, ESO–EC films had preferable mechanical properties and better thermal stability, as well as non-flammability. In addition, the water vapor permeability of ESO–EC films was lower than that of traditional plasticized films. Their oxygen permeability was also remained in a low level. These outstanding performances were related to the relatively high molecular weight, hydrophobicity, chemical structure of ESO, and the intermolecular interactions between ESO and EC chains.

The Co2+ ions doped ZnO magnetic semiconductor films, Zn 1-x Co x O, were prepared on glass substrate by Sol-Gel method. The microstructure of Zn 1-x Co x O thin films with different x value and its photoluminescence properties were investigated. The fluorescence spectroscopy was measured for the optical properties of Zn 1-x Co x O thin films and the influence of the doping content on luminescence performance was analyzed. The blue luminescence peak shows a red shift and the surface roughness shows a marked change with the doping content increasing.

Background : Vitamin D plays an important role in bone mineralization. Enamel and dentin are two mineralized tissues of different origins that are part of the tooth structure, but th

A novel method for mode optimization of a high-power laser is presented in this paper. A binary optical resonator is formed through introducing binary optical technology into a laser resonator. The traditional spherical mirrors are substituted by binary optical mirrors. Diffraction analyses show that this kind of resonator can construct any modes as desired with a strong ability of mode selecting and optimization. For a high-power CO2 laser, an optimum design of the binary optical resonator is implemented to obtain a fundamental-mode laser output with a uniform intensity distribution.© (1996) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A novel series of nanocomposite hydrogels based on cellulose nanocrystals (CNCs) and poly(acrylic acid) (PAA) have been synthesized by in situ free radical polymerization within an aqueous medium. Rheological measurements were applied to monitor the gelation process and results indicated that the gelation took place as monomers (acrylic acid, AA) grafted from the CNC surface and PAA chains entangled to produce flexible CNC–PAA gels. By tailoring the concentration of CNC (CCNC) over a wide range of 0.02–1 wt%, two critical CCNC, C* and C**, were found which corresponded to polymer chains that occurred in overlapping entanglements and promoted conformational rearrangements on the basis of earlier gel precursors, respectively. The formation mechanism of CNC based nanocomposite hydrogels, in which the nanoparticles transformed from the isolated state below C* to the spatially continuous percolation structure above C**, was proposed. The CNC–PAA gels exhibited excellent, composition-dependent mechanical properties, such as a large elongation ratio (>1100%) and high tensile strength (>350 kPa). Transmission electron microscopy (TEM) revealed that the CNCs were surrounded by grafted chains and formed inter-connected network structures, where the CNCs acted as multifunctional cross-links with an average effective functionality of 75. The mechanical measurements indicated that the increase of CCNC led to an increase in the hydrogels viscous characteristics and contributed to the energy dissipating mechanism, which was responsible for CNC–PAA gels excellent flexibility. The swelling and partial dissolution behaviors of the hydrogels were examined, focusing on the effect of CCNC on the gels characteristic partial deswelling and gel-to-sol transition. Some new chain entanglements were formed under concentrated conditions after drying treatment above the glass transition temperature (Tg) which was verified by observation of the greater tensile strength and modulus. All the results corresponded to the self-consistent network structure model for CNC–PAA gels.