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Methanol-to-olefins(MTO) reaction is one of the important non-petroleum routes to produce light olefins over acidic molecular sieves. In this study, the complete reaction course of MTO on SAPO-34 molecular sieve with retained organics evolution from induction period to deactivation period was investigated systematically at different weight hourly space velocities(WHSV) of methanol. By the aid of 12C/13C-methanol isotopic switch experiment, the dual cycle mechanism involving aromatics-based cycle and alkenes-based cycle was evaluated during the whole reaction process. The detailed reaction route varied with the evolution of the retained organics in the catalyst at different reaction stages. The aromatics-based cycle and alkenes-based cycle alternately dominate the reaction process. In the efficient reaction period, aromatics-based cycle is the main reaction mechanism, while in the induction and deactivation periods, the contribution of alkenes-based cycle mechanism will become more important.

Chopped basalt fibre (BF)-reinforced silicone rubber/fluorine rubber composites were investigated to improve their mechanical and thermal properties, in which the blend of silicone rubber (MVQ) and fluorine rubber (FKM) was used as a matrix of the composites, the BF was used as a reinforcement, and the coupling agents of KH550 (3-amino propyltriethoxysilane), KH590 (3-mercaptopropyl trimethoxysilane) and Si69 (bis(3-triethoxysilylpropyl) tetrasulfane) were used as the compatibiliser. The effect of length and content of the BF, and the type of coupling agent on the mechanical properties of composites were discussed. The results confirm that the mechanical and thermal properties of the KH590-BF/MVQ/FKM composites were optimal when the BF was 7 phr (parts per hundred rubber) with a length of 12 mm, and treated with coupling agent KH590 of 2.0 phr. Further compatibility between the BF and MVQ/FKM was optimum. The glass transition temperature (Tg) reduced from − 19.2 °C to − 28.0 °C, while the application range of KH590-BF/MVQ/FKM composites was widened.

This paper analyzed the effect of long period stacking ordered phases (LPSO) and aged-precipitations on corrosion behavior of Mg–6Gd–2Y–1Zn–0.3Zr magnesium alloys. As-forged alloys were subjected to aging at 225 °C for a period of 4 and 12 h such as to acquire the required microstructure. For these as-forged Mg alloys, some structures of LPSO phases were broken and replaced by fine dynamic recrystallized grains. After undergoing the aging treatment for a 4 h period, these alloys demonstrated a higher number of recrystallized grains and lesser LPSO phases. However, the 12 aging of the alloys produced the least number of LPSO phases, but produced a considerable amount of aged-precipitations on the recrystallized grains. During the period of 120 h immersion in 0.1 mol NaCl solution, the corrosion behavior of the alloys was mainly determined by the decreased volume fraction of LPSO phases and the increased volume fraction of aged-precipitations. Alloys after aging for a 12 h period, displayed the most critical corrosion rate owing to the severe micro-galvanic corrosion between high voltage aged-precipitations or LPSO phases and Mg-matrix, whereas, the alloys after aging for a 4 h period, displayed the best corrosion resistance due to the lesser volume fraction of LPSO phases. As-forged alloys with the most amount of volume fraction of LPSO phases displayed a moderate corrosion resistance.

We investigated the complex solidification behaviour of Al2O3–Y3Al5O12 eutectics prepared by laser engineered net shaping. Colony structure consisting of coupled irregular eutectic was dominant at interior region of as-fabricated specimens, and its growth behaviour was depicted by Magnin–Kurz model. In each deposited layer, The Y3Al5O12 phase within irregular eutectic grew through a competitive mechanism from random to oriented, whereas the orientation of Al2O3 remained unchanged. Transition from anomalous to colony coupled eutectics occurred at the bottom of each layer, and irregular to regular eutectics transition was recognized at outer region of as-built sample.

Traditional expanded graphite (EG) films exhibit excellent electric and thermal conductivities, due to weak oxidation degree induced low defect density. However, the stiff sheet structure makes EG films very brittle, which greatly limits its applications in next generation flexible electric devices. To overcome this challenge, ammonium persulfate ((NH4)2S2O8) is employed as both expansion agent and weak oxidation agent. As a result, the weak oxidation can effectively reduce the surface energy mismatching between EG and water, making it possible for EG to be exfoliated in water by high-speed shearing combined with sonication. Most particularly, the expansion step introduces plenty of wrinkles into the EG sheets, which notably improve the flexibility of EG films. Besides, using raw graphite with large lateral size and less (NH4)2S2O8 can greatly improve the final overall performances. The prepared EG films exhibit good electric and thermal conductivities of 2977 S/cm, 854 W/mK, respectively. 33.1 dB EMI shielding property is obtained with the film thickness of only 10 μm. Moreover, 800 times direct bending can be overcome without any structure break. This facial large scale and environmentally friendly method endows the films with great potential applications in flexible electric devices.

Thermally conductive but electrically insulating polymer composites have drawn much attention in various applications including thermal management, electronic packing, etc. Herein, a facile method of preparing polymer composites with both excellent thermal conductivity and electrical insulation is reported. To do this, nylon 6 (PA6)/Graphene nanoplatelets (GNPs) composites were firstly prepared via melt blending, then smashed into micron particles and coated with hexagonal boron nitride (h-BN) powder via VAE resin, finally hot compress molding to form composites. Thus depending on the content of GNPs inside PA6 particles and the content of h-BN coated on the particles, the thermal and electrical conductivity of the composites could be well controlled. For instance, at the total content of fillers is 18.82 vol%, with 1.97 vol% GNPs insides PA particles and 16.85 vol% h-BN coated on the surface, almost ten times improvement of thermal conductivity (from 0.29 to 2.69 W m−1k−1) has been achieved, while still maintain an excellent electrical insulating (as low as 4.13 × 10−9 S/m). It is proposed that this double segregated filler network could provide synergistic enhancement for the thermal conductivity, while the electrical conductivity caused by GNPs could be largely cut off by h-BN filler network. More importantly, this unique structure could be well preserved even after the sample thickness was decreased into a thin film, resulting in a further increase of thermal conductivity (up to 8.96 W m−1k−1) in the flow direction. Since various thermoplastic polymers can be chosen as matrix, and different filler combination can be adopted to construct thermal conductive synergistic and electrical insulating, we believe that this work provides a facial method to fabricate highly thermally conductive composites with a low electrical conductivity.

The production of large graphene oxide (GO) sheets is often limited by the huge diffusion resistance for oxidizing agents caused by the structural uniformity of large raw graphite flakes. Previous methods often rely on the thermal or microwave, hydrogen peroxide (H2O2) expansion to overcome the large diffusion resistance. However, the pretreatment is usually energy consuming and costs extra acid which may cause more environmental risks. Here, we discovered that adding ammonium persulfate ((NH4)2S2O8) to concentrated sulfuric acid as gas expansion agent for the pretreatment of graphite flakes can lead the graphite to form a porous structure and effectively improve the specific surface area of graphite, providing more contact area for graphite with oxidizing agents due to the rapid gas release. Thus, the diffusion resistance for oxidizing agents is remarkably reduced. As a result, graphite oxide with pretreatment shows higher oxidation degree (C/O ratio: 1.7) compared with graphite oxide without pretreatment (C/O ratio: 2.3). Besides, without any exfoliation method, the as obtained uniformly oxidized graphite oxide can self-exfoliate into monolayer GO sheets with a weight average size of 1263 μm2. Moreover, the vacuum filtrated GO films exhibit superior mechanical properties (Tensile strength: 80.9 MPa).

Expanded graphite (EG) films are known for high electric and thermal transportation properties, due to light oxidation preparation process compared with chemical converted graphene (cGE) films. However, the poor mechanical properties and brittle nature are the major limitations for commercial applications. To meet this challenge, in this work, hydrated aramid nanofiber (HANF) with excellent mechanical properties and flexibility is introduced into EG films to enhance their mechanical properties and flexibility. As a result, only the adding of 2 wt% HANF can endow EG films with good flexibility. The best comprehensive property is achieved by adding 10% HANF (EG-10). Compared with the pure EG films (EG-0), a 223% improvement of tensile strength from 7.5 Mpa to 24.2 Mpa and a 660% enhancement of elongation at break from 0.371% to 2.82% are observed for EG-10. Besides, EG-10 maintains good electric and thermal conductivities of 215 S cm−1, 208 W m−1 K−1. Moreover, the EMI shielding property of 34.9 dB is realized when the film thickness reaches only 30 μm. The EG/HANF films can be used up to the temperature of 300 °C and show good flame resistance compared with adding other polymers thanks to the good stability of HANF. And, the excellent flexibility can be maintained even after 1000 times direct folding. The comprehensive properties of light weight films, together with their advantages of simple, cheap and facile large-scale preparation process endow the films with promising applications in next generation foldable electronic devices.

We introduce a hyperuniform-disordered platform for the realization of near-infrared photonic devices on a silicon-on-insulator platform, demonstrating the functionality of these structures in a flexible silicon photonics integrated circuit platform unconstrained by crystalline symmetries. The designs proposed advantageously leverage the large, complete, and isotropic photonic band gaps provided by hyperuniform disordered structures. An integrated design for a compact, sub-volt, sub-fJ/bit, hyperuniform-clad, electrically controlled resonant optical modulator suitable for fabrication in the silicon photonics ecosystem is presented along with simulation results. We also report results for passive device elements, including waveguides and resonators, which are seamlessly integrated with conventional silicon-on-insulator strip waveguides and vertical couplers. We show that the hyperuniform-disordered platform enables improved compactness, enhanced energy efficiency, and better temperature stability compared to the silicon photonics devices based on rib and strip waveguides.

Expanded graphite (EG) films with low oxidation degree exhibit excellent thermal, electric properties and electromagnetic interference (EMI) shielding. However, the mechanical brittleness is the major limitation for their applications. To meet this challenge, in this work, a small amount of flexible graphene (GE) is introduced to endow EG films with good flexibility and mechanical properties by forming simulate shell structure. Moreover, the influence of oxidation degree and sheet thickness for carbon sheets as well as the lateral size of GE on the film performance is carefully discussed. As a result, a 431% enhancement of tensile strength from 7.7 Mpa to 40.9 Mpa and little sacrifice of electric, thermal conductivities up to 1467 S cm−1 and 348 W m−1 K−1 are observed with the loading of only 10% large GE (LGE) sheets in EG films. Besides, high EMI shielding of 48.3 dB is achieved as the film thickness reaches 43 μm. The excellent flexibility of prepared EG/LGE films can be retained even after more than 1000 times of direct folding. These excellent properties of light-weight EG/LGE films, together with their advantages of environmentally friendly and facile large-scale fabrication, endow the films with great potential applications in next-generation commercial portable flexible electronics.

As a traditional general plastic, polypropylene (PP) has been widely used in daily life. Glass fibers are often used to further reinforce the properties of PP for its application in engineering area. However, there are still some drawbacks existing for glass fibers filled polypropylene composites, such as high filler content, easy fracture of glass fibers and damage to the machines during processing. Therefore, organic fibers are considered as an ideal candidate to replace glass fibers. In this work, short Kevlar fibers (KFs) modified by ball milling in phosphoric acid and surface hydrolyzation were introduced to PP matrix to improve the interfacial interaction and mechanical properties. It is found that KFs were exfoliated into several flaky microfibers and then broken into pieces during the ball milling process. With the aid of phosphoric acid, the KFs can be split further thereby increasing specific surface area greatly. Then the original and milled KFs were hydrolyzed by NaOH aqueous solution in order to introduce OH group on the surface of KFs. The dispersion and mechanical properties of PP reinforced with various KFs, including original, ball milled, and hydrolyzed, were investigated and compared. It was found that the combination of ball milling in phosphoric acid and surface hydrolyzation is the most effective way for enhancement of interfacial reaction and mechanical properties. Adding 10 wt. % of KFs could lead to an increase of tensile strength of PP from 30 MPa to 47 MPa, which only can be achieved by adding at least of 25 wt. % of glass fibers. The tensile test shows that hydrolyze of KFs surface are a more important factor to promote the interfacial interaction between fibers and matrix. Our work demonstrates that PP can be enhanced efficiently by the introduction of hydrolyzed and microfibrillated KFs. Although KFs are expensive compared with glass fiber at this moment, their high reinforcement efficiency and toughness could make them competitive as reinforcing filler for the preparation of advanced polymer composites with excellent mechanical and processing properties.

In the past two decades, the reaction mechanism of C-C bond formation from methanol or dimethyl ether (DME) has been intensively studied as the most critical problem of methanol to hydrocarbons (MTH) process, one of the most important reactions in C1 chemistry, but the first C-C bond generation during the very initial reaction stage remains a highly controversial issue. For the first time, a surface methyleneoxy-analogue, originated from the surface activated DME, was directly observed by in situ solid-state NMR and recognized to be the crucial intermediate for the first C-C bond formation in MTH process. In consequence, new insights into the first C-C bond formation were provided, suggesting DME/methanol activation and C-C bond direct formation via an interesting synergetic mechanism, involving C-H bond breakage and C-C bond coupling during the initial methanol reaction in the chemical environment of zeolite catalysis.

Thermal radiation with a narrow-band emission spectrum is of great importance in a variety of applications such as infrared sensing, thermophotovoltaics, radiation cooling, and thermal circuits. Although resonant nanophotonic structures such as metamaterials and nanocavities have been demonstrated to achieve the narrow-band thermal emission, maximizing their radiation power toward perfect emission still remains challenging. Here, based on the recently developed quasi-normal mode theory, we prove that thermal emission from a nanoscale transmission line resonator can always be maximized by tuning the waveguiding loss of the resonator or bending the structure. By use of nanoscale transmission line resonators as basic building blocks, we experimentally demonstrate a new type of macroscopic perfect and tunable thermal emitters. Our experimental demonstration in conjunction with the general theoretical framework from the quasi-normal mode theory lays the foundation for designing tunable narrow-band thermal emitters with applications in thermal infrared light sources, thermal management, and infrared sensing and imaging.

There are principally two mechanisms to improve the impact resistance of polymer-based composites, intrinsic toughening and extrinsic toughening. But the interplay between them is far from being well understood. Here, glass fiber was incorporated into polypropylene to promote extrinsic toughening mechanism, while addition of elastomer and annealing were adopted for intrinsic toughening. In this way, the interaction among glass fiber, elastomer and annealing could be discussed based on various characterizations, and their combined effect on mechanical properties of the composites could be determined. The results show that the intrinsic toughening mechanism of elastomer will be suppressed by glass fiber irrespective of the support of annealing, though annealing could work synergistically with glass fiber to toughen polypropylene. The possible structure-property relations are discussed. This work will provide deeper insight into the toughening behavior of polymer composites and practical guidance for the design of composites with excellent stiffness-toughness balance.

Hollow carbon nanospheres (HCNSs) were fabricated by annealing the Cu–C core–shell nanoparticles at 1250 °C in vacuum. The as-obtained HCNSs have ultrathin shell of 1–3 nm in thickness, small size of about 20 nm in diameter, high surface area of 300 m2 g–1, and ultrasmall pores below 5 nm within the C shells. The HCNSs exhibit excellent electrochemical performance as anode materials for lithium-ion batteries. A reversible capacity of 400 mAh g–1 and capacity retention of nearly 100% are achieved at the current density of 186 mA g–1 after 100 charging–discharging cycles. The high reversible capacity, improved high-rate capability, and outstanding cycling stability could be attributed to their unique structural characteristics including the extremely small diameter, the high surface area and the hollow structure with porous, ultrathin shell.

Hierarchical zeolite monoliths with multimodal porosity are of paramount importance as they open up new horizons for advanced applications. So far, hierarchical zeolites based on nanotube scaffolds have never been reported. Inspired by the organization of biominerals, we have developed a novel precursor scaffolding-solid phase crystallization strategy for hierarchical zeolites with a unique nanotube scaffolding architecture and nanotube-trimodal network, where biomolecular self-assembly (BSA) provides a scaffolding blueprint. By vapor-treating Sil-1 seeded precursor scaffolds, zeolite MFI nanotube scaffolds are self-generated, during which evolution phenomena such as segmented voids and solid bridges are observed, in agreement with the Kirkendall effect in a solid-phase crystallization system. The nanotube walls are made of intergrown single crystals rendering good mechanical stability. The inner diameter of the nanotube is tunable between 30 and 90 nm by varying the thickness of the precursor layers. Macropores enclosed by cross-linked nanotubes can be modulated by the choice of BSA. Narrow mesopores are formed by intergrown nanocrystals. Hierarchical ZSM-5 monoliths with nanotube (90 nm), micropore (0.55 nm), mesopore (2 nm) and macropore (700 nm) exhibit superior catalytic performance in the methanol-to-hydrocarbon (MTH) conversion compared to conventional ZSM-5. BSA remains intact after crystallization, allowing a higher level of organization and functionalization of the zeolite nanotube scaffolds. The current work may afford a versatile strategy for hierarchical zeolite monoliths with nanotube scaffolding architectures and a nanotube-multimodal network leading to self-supporting and active zeolite catalysts, and for applications beyond.

Two-dimensional nanolayers have found increasingly widespread applications in modern flexible electronic devices. Their adhesion with neighbouring layers can significantly affect the mechanical stability and the reliability of those devices. However, the measurement of such adhesion has been a great challenge. In this work, we develop a new and simple methodology to measure the interfacial adhesion between a mica nanolayer (MNL) and a single-layer graphene (SLG) supported by a SiO2 substrate. The method is based on the well-known Obreimoff method but integrated with innovative nanomanipulation and profile measuring approaches. Our study shows that the adhesion energy of MNLs on the SLG/SiO2 substrate system is considerably lower than that on the SiO2 substrate alone. Quantitative analyses reveal that the wrinkles formed on the SLG can considerably lower the adhesion. This outcome is of technological value as the adhesion maybe tailored by controlling the wrinkle formation in the graphene layer in a flexible electronic device.

Mica nanolayers (MNL) are a new dielectric material that can improve the electron transport properties of Si based microelectronic devices. However, the mechanical reliability of such devices is not well understood because measurement of the adhesion between an MNL and a Si substrate is insufficiently accurate. The recent work reports a bridging method that is developed based on the linear beam theory and can characterize the adhesion of MNL on a mica substrate in a reasonably accuracy. In this work, the accuracy of the bridging method is improved by using a nonlinear mechanical model. 15 MNL specimens are measured on a Si substrate in air and the new model gives an average adhesion energy of 119.69 ± 20.47 mJ m. The effect of environment on the adhesion is also investigated. The increase in temperature from 25 to 300 °C enhances adhesion, attributed to the increased bonding effect of interfacial contaminants. When humidity is below a threshold value, 80% in this case, the adhesion energy remains unchanged, but above the threshold, the nanobridges collapse during testing. Molecular dynamics simulation reveal that the collapse is because the increase of interfacial water molecules reduces the frictional force between the MNL and Si substrate.

Conformance improvement for ultra-high-temperature (130 °C) reservoirs is challenging due to the poor thermostability of conventional preformed particle gel (CPPG). To overcome the defect of thermal degradation, a novel hydrostable PPG (HT-PPG) was developed using the high-temperature tolerant crosslinker. In this work, a comparative study between the HT-PPG and CPPG has been presented in respects of their swelling behaviors, rheology properties and thermal stabilities. Particle swelling behaviors and viscoelasticities were firstly assessed in ambient. Using the swollen particles, a long-term aging at 130 °C underwent during which the physical status was monitored through high pressure vials (HPV). Furthermore, characterizations involved Scanning Electron Microscope (SEM) and Fourier Transform-Infrared Spectroscopy (FT-IR) were performed for both virgin and aged specimen. Thereby, an observation of gel microstructures and elucidation upon bonds or functional groups were provided. In addition to aging tests, we deployed the Differential Scanning Calorimetry (DSC) to investigate the inflection temperature as another indicator of particle thermostability. Attributed to the hydrostable crosslinker, the HT-PPG withstood 130 °C for at least 90 d. It was found that the HT-PPG effectively maintained its particulate shape, whereas, the CPPG completely degraded after 3-d aging. The HT-PPG maintained 28.8% of its initial storage modulus (G′). On the contrary, the normalized elasticity (G′/G0‘) of CPPG was only 0.43%. The SEM morphologies illustrated HT-PPG kept its rigid microstructure even after 90-d aging, while indicated destruction within CPPG network. According to FT-IR characterization, the decomposition of pristine crosslinker, N,N′-Methylenebisacrylamide in CPPG may account for its instability. DSC measurements furtherly demonstrated the favorability of HT-PPG in which HT-PPG exhibited a higher inflection temperature of 133.1 °C, however, CPPG only had an inflection temperature of 127.7 °C. This work turned out the novel HT-PPG could withstand ultra-high-temperature (130 °C) for more than 90 d, maintaining its particulate shape and viscoelasticity. This a durable plugging agent was notably superior to the CPPG, offering a candidate material for the conformance improvement in ultra-high-temperature reservoirs.

The applications of Polylactide (PLA) microspheres in biomedical areas are greatly determined by the size, morphology and internal structure. Taking advantage of the formation of stereocomplex (SC) crystallites between poly(L-lactide) (PLLA) and poly(D-lactide) (PDLA), we propose a facile strategy to prepare PLA microspheres with tunable morphology and crystalline structure by compounding PLLA and PDLA. With increasing PDLA content, the crystallinity of SC-PLA rose gradually until the ratio of PLLA and PDLA reached 1:1 and then fell. Correspondingly, the morphology of the microspheres were varied (smooth, porous, golf-ball like, guava like) and higher crystallinity of SC-PLA would lead to a more coarse and porous structure. Finally, three typical kinds of Rifampicin-loaded microspheres with different ratio of PLLA and PDLA (7:3, 3:7, 10:0, sorted by porosity from high to low) were prepared and the release behavior was compared. At 30 h, the cumulative release of 7:3, 3:7 and 10:0 microspheres were 32.6%, 17.8% and 6.0% respectively, indicating that the release profiles were generally determined by the porosity of the microspheres. Our findings not only provide a new strategy to prepare PLA microspheres with controllable morphology but offer additional possibilities for the applications of SC-PLA products in biomedical area.

FeCo-C core-shell nanoparticles (NPs) with diameters of 10-50 nm have been fabricated on a large scale by one-step metal-organic chemical vapor deposition using the mixture of cobalt acetylacetonate and iron acetylacetonate as the precursor. The Fe/Co molar ratio of the alloy nanocores and graphitization degree of C shells, and thus the magnetic and electric properties of the core-shell NPs, can be tuned by the deposition temperature ranging from 700 °C to 900 °C. Comparative tests reveal that a relatively high Fe/Co molar ratio and low graphitization degree benefit the microwave absorption (MA) performance of the core-shell NPs. The composite with 20 wt% core-shell NP obtained at 800 °C and 80 wt% paraffin exhibits an optimal reflection loss [Formula: see text] of -60.4 dB at 7.5 GHz with a thickness of 3.3 mm, and an effective absorption bandwidth (frequency range for RL ≤10 dB) of 9.2 GHz (8.8-18.0 GHz) under an absorber thickness of 2.5 mm. Our study provides a facile route for the fabrication of alloy-C core-shell nanostructures with high MA performance.

Enhanced visible light photocatalytic activity of Bi2WO6 photocatalyst modified with different ratio of polyvinyl pyrrolidone (PVP) was synthesized by a facile solvothermal process. The as-prepared photocatalysts were characterized by X-ray diffraction, field emission scanning electron microscopy, transmission electron microscopy, X-ray photoelectron spectroscopy, UV–Vis diffuse reflectance spectra and photoluminescence spectra. The results indicated that the addition of PVP could control the particle morphology of bismuth tungstate catalyst to form high phase purity of Bi2WO6. The solvent-thermal reaction time was critical in deciding the structure and shapes of the catalysts, and the optimal solvent-thermal reaction time was 24 h. The photocatalytic activities of the PVP-Bi2WO6 catalysts were determined by photocatalytic degradation of tetracycline hydrochloride (TCH) in aqueous solution under visible light irradiation. Optical properties and the TCH degradation results showed that PVP-Bi2WO6 catalysts exhibited enhanced photodegradation for TCH under visible-light irradiation. Among them, P5 (PVP % = 1.0 wt%) exhibited the best photocatalytic activity for degradation ratio of TCH reaching 86.88 % in 90 min.

In this study, we proposed a new strategy to fabricate polylactide (PLA) based conductive polymer composites with excellent electrical conductivity, superior electromagnetic interference shielding efficiency (EMI SE) and good mechanical properties using a Pickering emulsions method. Cellulose nanocrystals (CNCs) were used as a stabilizer for oil-in-water Pickering emulsions and a dispersant for carbon nanotubes (CNTs) at the same time. CNC/CNT suspensions and dichloromethane (DCM) solution of PLA were used as aqueous phase and oil phase respectively. With the evaporation of DCM, PLA microparticles coated by entangled CNCs and CNTs could be formed. After compression molding, the PLA/CNC/CNT composites showed an outstanding EMI SE of 41.8 dB with only 4.3 wt% CNT loading. Simultaneously, the mechanical performance of the sample maintained a high level (tensile strength: 45.52 MPa, Young’s Modulus: 3152 MPa). Our findings provide a simple, cost-effective and environmentally friendly manufacturing route for functional polymer nanocomposites with excellent comprehensive properties.

We investigate the directional control of narrow-band perfect thermal emission using a nanoscale Yagi–Uda antenna. Although Yagi–Uda antennas were demonstrated to achieve directional control in the optical and radio frequency regimes, they have not been applied for thermal infrared emission. Here, by coupling a nanoscale thermal emitter into a Yagi–Uda antenna, we demonstrate strong directional control of thermal emission with a narrow-band spectrum at the nanoscale. By exploring the effects of the reflector and the director of a Yagi–Uda antenna, the forward emission enhancement factor up to 8.3 is achieved through geometry optimization.

Mica nanolayers have great potential for applications in the future flexible electronics due to their excellent flexibility and dielectric properties. Characterization of the adhesion behaviors of mica nanolayers is thus essential, as they would substantially affect the reliability of the electronic devices. In this work, a new delamination method is developed based on the optical microscopic nanomanipulation for measuring the adhesion energy of mica nanolayers. In particular, the tests are performed under different environmental conditions with relative humidity varying from 10% to 90% and temperature ranging from 25 to 300 °C. The average surface energy of mica nanolayers is 221.5 ± 25.4 mJ m measured at the room temperature of 25 °C and decreases with the increase in relative humidity or temperature. The finding of the environmentally dependent adhesion is of importance for the design of flexible electronics products based on mica nanolayers.

A novel method relying on atomic force microscope (AFM) tip based nanomachining is presented to enable the fabrication of microchannels that exhibit complex three-dimensional (3D) nanoscale floor surface geometries. To achieve this, reciprocating lateral displacements of the tip of an AFM probe are generated, while a high-precision stage is also actuated to move in a direction perpendicular to such tip motions. The width and length of microchannels machined in this way are determined by the amplitude of the tip motion and the stage displacement, respectively. Thus, the processing feed can be changed during the process as it is defined by the combined control of the frequency of the tip reciprocating motions and the stage speed. By employing the built-in force feedback loop of conventional AFM systems during such operations, the variation of the feed leads to different machined depths. Thus, this results in the capability to generate complex 3D nanostructures, even for a given normal load, which is set by the AFM user prior to the start of the process. In this paper, the fabrication of different microchannels with floor surfaces following half triangular, triangular, sinusoidal, and top-hat waveforms is demonstrated. It is anticipated that this method could be employed to fabricate complex nanostructures more readily compared to traditional vacuum-based lithography processes.

We present experimental and theoretical results to describe and explain processing outcomes when producing nanochannels that are a few times wider than the atomic force microscope (AFM) probe using an AFM. This is achieved when AFM tip-based machining is performed with reciprocating motion of the tip of the AFM probe. In this case, different feed directions with respect to the orientation of the AFM probe can be used. The machining outputs of interest are the chip formation process, obtained machined quality, and variation in the achieved channel depth. A three-sided pyramidal diamond probe was used under load-controlled conditions. Three feed directions were first investigated in detail. The direction parallel to and towards the probe cantilever, which is defined as “edge forward”, was then chosen for further investigation because it resulted in the best chip formation, machining quality, and material removal efficiency. To accurately reveal the machining mechanisms, several feed directions with different included angles for the pure edge-forward direction were investigated. Upon analysis of the chips and the machined nanochannels, it was found that processing with included angles in the range 0–30° led to high-quality channels and high material-removal efficiency. In this case, the cutting angles, such as the rake angle, clearance angle, and shear angle, have an important influence on the obtained results. In addition, a machining model was developed to explain the observed machined depth variation when scratching in different feed directions.

This study investigates the efficiency of carbon nanotubes (CNTs) as reinforcement for polypropylene (PP) for biocompatible application as a function of different surface functionalization of CNTs. PP composites were reinforced using various CNTs: single- and multi-walled carbon nanotubes (SWCNTs, MWCNTs), SWCNTs were covalently functionalized by plasma, for comparison, the MWCNTs were functionalized noncovalently. Different CNTs were incorporated into PP by solution blending. The type of CNTs and surface functionalization affects the mechanical and biocompatibility results significantly. Differences in nanostructure and the chemical compositions, number of functional groups, and structural defects for the CNTs may be the key factors affecting the mechanical properties and biocompatibility of PP nanocomposites compared to the neat PP. Finally, suitable CNTs and surface functionalization of CNTs were selected for making the PP/CNTs composites.

A novel fluoride ion adsorbent, which uses natural clay modified by lanthanum and aluminum, was successfully prepared. The adsorbent was characterized by scanning electron microscope, BET surface area measurement, and X-ray photoelectron spectroscopy. Batch experiments were carried out to investigate the adsorbent performance for fluoride ion. Fluoride ion adsorbent onto modified clay followed the pseudo-second order kinetic model with the correlation coefficient value of 0.9846. The isotherm data was well fitted to the Langmuir model. The adsorption capacity of the modified clay was 1.3033 mg/g. The optimum pH value for fluoride ion removal was 6. The modified clay adsorbent can be regenerated by KAl(SO4)2·12H2O. Six times’ regeneration experiments showed that the regeneration rate of the modified clay still higher than 80 %, and the mass loss rate lower than 10 %. The modified clay performed strong adsorption capacity for fluoride ion and high regeneration rate. It could be a cost-effective adsorbent to remove fluoride from groundwater in undeveloped regions.

The strategy of phase control has been playing an important role in optimizing the electromagnetic wave (EMW) absorption properties. Here, Ni nanoparticles (NPs) with two phases, hexagonal close-packed Ni (HCP-Ni) and face-centered cubic (FCC-Ni), coated by C shells are synthesized by metal-organic chemical vapor deposition. The average size of the Ni nanocores and thickness of C shells are about 10 and 4 nm, respectively. After blended with paraffin wax at a mass ratio of 1:5, the Ni-C core- shell NPs exhibit excellent EMW absorption properties with an optimal reflection loss of -52.6 dB and a large effective bandwidth (BWeff) of 9.3 GHz. The core-shell NPs annealed in vacuum to remove the metastable HCP-Ni exhibit degraded EMW absorption properties. Comparative analyses reveal that the HCP-Ni phase in the core-shell NPs can enhance the dielectric loss and thus improve the impedance matching, suggesting that phase control should be a practicable strategy for optimizing the properties of Ni-based EMW absorption materials.

The preparation of graphene oxide (GO) via Hummers method is usually divided into two steps: low temperature oxidation at 35 °C (step I oxidation) and high temperature oxidation at 98 °C (step II oxidation). However, the effects of these two steps on the exfoliation capability and chemical structure of graphite oxide remain unclear. In this study, both the functional group content of graphite oxide and the entire evolution of interlayer spacing were investigated during the two steps. Step I oxidation is a slowly inhomogeneous oxidation step to remove unoxidized graphite flakes. The prepared graphite oxide can be easily self-exfoliated but contains a lot of organic sulfur. During the first 20 min of step II oxidation, the majority of organic sulfur can be efficiently removed and graphite oxide still remains a good exfoliation capability due to sharp increasing of carboxyl groups. However, with a longer oxidation time at step II oxidation, the decrease of organic sulfur content is slowed down apparently but without any carboxyl groups forming, then graphite oxide finally loses self-exfoliation capability. It is concluded that a short time of step II oxidation can produce purer and ultralarge GO sheets via self-exfoliation. The pure GO is possessed with better thermal stability and liquid crystal behavior. Besides, reduced GO films prepared from step II oxidation show better mechanical and electric properties after reducing compared with that obtained only via step I oxidation.

Co-C core-shell nanoparticles have been synthesized in large quantity (in grams) by metal-organic chemical vapor deposition with analytical cobalt (III) acetylacetonate as precursor. Extremely small nanoparticles with an average core diameter of 3 nm and a shell thickness of 1-2 nm, and relatively large nanoparticles with an average core diameter of 23 nm and a shell thickness of 5-20 nm were obtained, depending on the deposition regions. The 3 nm Co nanocores are thermally stable up to 200 °C in air atmosphere, and do not exhibit visible structural and morphological changes after exposure to air at room temperature for 180 d. The extremely small core-shell nanoparticles exhibit typical superparamagnetic behaviors with a small coercivity of 5 Oe, while the relative large nanoparticles are a typical ferromagnetic material with a high coercivity of 584 Oe. In the microwave absorption tests, a low reflection loss (RL) of -80.3 dB and large effective bandwidth (frequency range for RL -10-dB) of 10.1 GHz are obtained in the nanoparticle-paraffin composites with appropriate layer thicknesses and particle contents. This suggests that the as-synthesized Co-C core-shell nanoparticles have a high potential as the microwave-absorbing materials.

Fe3C-C core-shell nanoparticles were fabricated on a large scale by metal-organic chemical vapor deposition at 700 °C with ferric acetylacetonate as the precursor. Analysis results of x-ray diffraction, transmission electron microscope and Raman spectroscope showed that the Fe3C cores with an average diameter of ∼35 nm were capsulated by the graphite-like C layers with the thickness of 2-5 nm. The comparative experiments revealed that considerable Fe3O4-Fe3C core-shell nanoparticles and C nanotubes were generated simultaneously at 600 and 800 °C, respectively. A formation mechanism was proposed for the as-synthesized core-shell nanostructures, based on the temperature-dependent catalytic activity of Fe3C nanoclusters and the coalescence process of Fe3C-C nanoclusters. The Fe3C-C core-shell nanoparticles exhibited a saturation magnetization of 23.6 emu g(-1) and a coercivity of 550 Oe at room temperature.