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This paper presents an efficient and simple processing method for the fabrication and regulation of nano-scale wrinkle patterns. The stiff film is created through cross-linking the surface of ultrathin polymer film within twenty nanometers by using the hyperthermal hydrogen induced cross-linking (HHIC) method, and then the bilayer is heated above the glass transition temperature of the polymer before quenched to room temperature. In this way, wrinkle patterns with wavelength ranging from 150 to 300 nm are prepared. And a morphology transition between the pattern of single points (convex bumps) and the pattern of ridges (labyrinth) is observed. The formation of wrinkle patterns is systematically investigated as functions of the thickness of original ultrathin film, the time of HHIC treatment, the annealing temperature and the chemical structure of polymers. Furthermore, nano-patterned silicon wafer is used as a template to create multiscale, anisotropic wrinkle patterns. [ABSTRACT FROM AUTHOR]

Abstract: In this work, the chitosan ternary nanocomposites with two-dimensional (2D) clay platelets and one-dimensional (1D) CNTs have been successfully prepared by a simple solution-intercalation/mixing method in acid media. It was found that the thermal degradation temperature of chitosan (at 50% weight loss) could be only improved in about 20–30°C by adding 3wt% either clay or CNTs, however, almost 80°C increase of degradation temperature could be achieved by adding 2wt% clay and 1wt% CNTs together. Dynamic mechanical measurement demonstrated an obviously improved storage modulus for chitosan/clay–CNTs than that for the corresponding binary chitosan/clay or chitosan/CNT nanocomposites with the same total filler content (3wt%). For the solvent vapor permeation properties, a largely improved benzene vapor barrier property was observed only in chitosan/clay–CNT ternary nanocomposites and depended on the ratio of clay to CNTs. XRD, SEM and TEM results showed that both clay and CNTs could be well dispersed in the ternary nanocomposites with the nanotubes located around the clay platelets. FTIR showed an improved interaction between the fillers and chitosan by using both clay and CNTs. A much enhanced solid-like behavior was observed in the ternary nanocomposites, compared with the corresponding binary nanocomposites with the same total filler content, as indicated by rheological measurement. The unique synergistic effect of two-dimensional (2D) clay platelets and one-dimensional (1D) CNTs on the property enhancement could be tentatively understood as due to a formation of much jammed filler network with 1D CNTs and 2D clay platelets combined together. Our work demonstrates a good example for the preparation of high performance polymer nanocomposites by using nanofillers with different dimensions together. [Copyright &y& Elsevier]

Abstract Boron carbide (B 4 C) is an important type of neutron radiation shielding material with relatively high efficiency due to the high content of 10B element. Incorporation of B 4 C particles into polymer to prepare high-performance neutron radiation shielding material has become more and more important for the safe operation of nuclear power in the defense industry and nuclear power plant. The polyimide/B 4 C composite films with different micro-sized B 4 C contents were successfully prepared by in-situ polymerization. Silane coupling agent KH550 was employed to functionalize B 4 C particles to improve the dispersion of B 4 C particles in the polyimide matrix with strengthened interfacial interaction. As shown that the micro-sized B 4 C functional particles can be well dispersed in the BPDA/ODA polyimide matrix. With the B 4 C content increase, thermal stability of the polyimide/B 4 C composite films can be significantly improved, even mechanical properties partly declined. Meanwhile, the polyimide/B 4 C composite films exhibit good thermal neutron radiation shielding properties. The neutron permeability I/I 0 changes exponentially with the change of B 4 C content. When the B 4 C content is increased to 30 wt%, the polyimide/B 4 C composite films show optimum properties combination with thermal decomposition temperature (T d 10) of 622 °C, neutron permeability (I/I 0) of 0.24 (800 μm in thickness), and tensile strength of 406 MPa. The composite thus shows great potential for use in applications which require materials with high thermal stability and neutron radiation shielding ability, such as fusion reactor system and nuclear waste disposal. [ABSTRACT FROM AUTHOR]

In order to enhance the design life of laminated rubber bearings in the field of highway bridges in the plateau region, a novel laminated bearing was made by the modified ethylene propylene diene monomer (EPDM) rubber that combines both low-temperature and ageing resistance properties in this work. The modified EPDM also exhibit a high anti-peel strength with reinforced steel plate layer. Experimental and numerical investigations were carried out to evaluate the mechanical properties and failure conditions for the EPDM laminated bearing. The results indicate that the bearing with different shape factors exhibit good mechanical properties, and its key performance parameters such as compressive modulus and shear stiffness meet the requirements of the current specification for highway bridges. Meanwhile, we have established a quantitative relationship between the proportion of void area and the total local shear strain for EPDM laminated bearing, and found that when the proportion of void area reaches more than 32 %, some of the performance indexes of the bearing will exceeds the design limit. The above research results can be used as an important criterion for evaluating the performance of modified EPDM bearings. • A laminated bearing was manufactured using a modified EPDM rubber with excellent anti-peel strength. • The modified EPDM bearings with different shape factors meet the requirements of the specifications. • An empirical model is established to characterise the failure condition of EPDM bearing under ultimate load. [ABSTRACT FROM AUTHOR]

Flexible light/electrically responsive inorganic-organic phase-change materials (PCMs) have promising applications in thermal management and wearable health monitoring. Herein, flexible hydrogel PCMs with excellent light-to-thermal energy conversion efficiency and strain sensing capability were synthesized by loading sodium acetate trihydrate (SAT)/expanded graphite (EG)/borax/carboxymethylcellulose sodium (CMC) (termed SEBC) composites into a polyacrylamide (PAM)/chitosan (CS)/graphene (GNPs) (termed PCG) bi-networked hydrogel via a facile one-step strategy. The resulting composites showed excellent self-adhesion properties, tensile cycling stability, thermal stability, high melting enthalpy (119.7 J/g), and low water loss rate (0.41 %, at 70 °C). Benefiting from the light-absorbing ability and electrical conductivity of EG and GNPs, the hydrogel composite exhibited a high light-to-thermal energy conversion efficiency of 92.2 % and meanwhile can absorb excessive thermal energy to regulate the thermotherapy temperature on human joints under infrared light. Besides, the hydrogel composite can act as a strain sensor with an excellent gauge factor value of 2.73 by changing conductive network (EG and GNP) resistance to monitor the recovery of patient's joint activities. This multifunctional inorganic-organic phase-change hydrogels present good potential for personalized healthcare. [Display omitted] • Shape-stabilized sodium acetate trihydrate flexible hydrogel phase change composites were prepared by a one-step strategy. • The hydrogel composites exhibited an excellent light-to-thermal conversion efficiency of 92.2 %. • The hydrogel composites-based strain sensor had an excellent GF value of 2.73 [ABSTRACT FROM AUTHOR]

Abstract: Sodium hydrosulfite is used to reduce graphite oxide in current study. The preparation of poly (vinyl alcohol) (PVA)/graphene nanocomposites is realized using two simple steps: the synthesis of PVA/graphite oxide (GO) nanocomposites film and immersion of such a film in the reducing agent aqueous solution. This method prohibits the agglomeration of GO during direct reduction in PVA/GO aqueous solution, and opens a new way to scale up the production of graphene nanocomposites using a simple reducing agent. A 40% increase in tensile strength and 70% improvement in elongation at break have been obtained with only the addition of 0.7wt.% of reduced graphite oxide. Furthermore, a good level of conductivity and a variation in the surface property of the prepared films have been observed for the composites containing graphene. [Copyright &y& Elsevier]

Abstract: Dibenzylidene sorbitol (DBS) exists in the form of fibril and usually acts as an effective nucleating agent to facilitate crystallization of polyolefin during manufacturing. In this research, the isothermal crystallization of isotactic polypropylene (iPP) containing different amounts of DBS was followed by dynamic rheometry, and described upon a viewpoint of viscoelastic property evolution. Since the adopted temperatures within the entire sample preparation and characterization process were below the melting point of DBS, the DBS additives played a role of only solid nucleating agent, thus the possible effect of a changed miscibility between iPP and DBS on the viscoelastic properties as change of temperature could be ignored. Although saturation of nucleating iPP was observed at 0.1% DBS concentration, a negative influence with further increasing DBS content on the crystallization of iPP was determined for the first time via time sweep of G′ upon a single angular frequency and application of “inverse quenching” protocol within a wide range of angular frequency. Even more, a largely increased G′ and viscosity were observed in the melt as decreasing the temperature of iPP containing 0.1% DBS, suggesting a strong quasi-solid like behavior before iPP crystallization. A complement for well understanding the crystallization of iPP containing nucleating agent was discussed based on the formation of the DBS fibrils'' network, the interfacial tension between crystalline/amorphous phase, and the consistency of crystallizing lamellae. Our study demonstrates clearly that the crystalline characteristic upon saturation of heterogeneous nucleating is difficult to be detected by traditional means, but could be followed reasonably by rheological measurements which is much sensitive to the microstructural changes. [Copyright &y& Elsevier]

Abstract Here, we report a dual-use surface-enhanced Raman scattering (SERS) substrate based on a flexible three-dimensional (3D) chitosan foam, onto which silver nanoparticles (Ag NPs) are firmly immobilized through amino groups from chitosan chains. The SERS substrate can actively collect analytes either on solid surface by swabbing or in solution by adsorption. The compressible characteristic of chitosan foam enables easy removal of solvent through gentle pressing, which can achieve fast pre-concentrating of analytes before measurements. In addition, the substrate is shape adaptable and thus is suitable for sampling contaminants on solid surfaces. The SERS substrates exhibit acceptable reproducibility (16.4% in relative standard deviation). Furthermore, it detects Raman probe Nile Blue A down to 5 pg by swabbing solid surface and Rhodamine 6G down to 10 ppb by adsorbing analyte in the solution. Three pesticide samples (triazophos, methidathion, and isocarbophos) can also be detected down to μg level with the substrate. It is believed that such a versatile SERS substrate may find great opportunity in realistic sensing applications. Graphical abstract A 3-D chitosan based dual use SERS substrate has been proposed for the direct sampling and sensing of analytes from surface and solution. fx1 Highlights • A SERS substrate based on Ag NPs loaded 3-D chitosan foam has been developed. • The SERS substrate exhibits high sensitivity and commendable reproducibility. • The substrate can directly collect analytes on solid surface as well as in solution. • Solvent can be expelled from the substrate through squeezing for quickly pre-concentrating analytes. [ABSTRACT FROM AUTHOR]

Special wettability of biological surfaces usually depends on the unique micro-structures and surface chemistry natures. However, current preparation methods often involve complex processing steps or expensive moulds and have the limited ability to simulate these ordered and elaborate micro-structures. Herein, we report a facile and mould-free approach to fabricate special wetting surfaces by patterning an ordered porous structure with various geometric parameters via one-step 3D printing of Polydimethylsiloxane (PDMS) ink. By adjusting pore structure at sub-millimeter scale, the printed PDMS porous films can present versatile special surface wettabilities such as superhydrophobicity and anisotropic wettability. With the guide of computer program, water contact angles (WCAs) along parallel and perpendicular directionsand anisotropy wetting degree of the printed film can be tailored by controllingprinting speed and filament spacing. Through optimizing the geometrical parameters, a superhydrophobic PDMS filmwith a WCA of about 155° is obtained, which mainly depends on the sub-millimeter scale structure. The superhydrophobicity of the printed porous PDMS film also exhibits excellent durability against thermal aging. Our work demonstrates that the printed superhydrophobic porous film can be used for some attracting applications such as air-breathable water-proofing, water-repellent floating carrier, and no-loss liquid transfer. [ABSTRACT FROM AUTHOR]

Fast-charging lithium-ion batteries (LIBs) have recently received significant attention. In current commercial LIBs, lithium precipitation frequently occurs under long-term cycling and fast-charging conditions, adversely affecting their cycle capacity retention and safety. The primary cause of lithium precipitation is electrolyte loss during long-term cycling. In this study, a thermoplastic polyurethane/polyurethane acrylate semi-interpenetrating polymer network ceramic separator with high electrolyte retention (200%) and interfacial adhesion (6.6 N) is prepared and without a decrease in the energy density. The LiNi 0.8 Mn 0.1 Co 0.1 O 2 /graphite batteries fabricated with this separator show excellent electrochemistry properties (300 cycles, 1.5 C, discharge capacity of 3677 mAh, capacity retention of 93%). Furthermore, this study presents a novel strategy to mitigate the issue of lithium precipitation in fast-charging LIBs. Therefore, this functional separator is a promising alternative for the conventional commercial polyvinylidene difluoride separators and provides a new avenue for developing the next generation of fast-charging devices. [Display omitted] • The root cause of lithium precipitation in fast-charging conditions was explored. • A ceramic separator with semi-interpenetrating polymer network was prepared. • The separator displayed high electrolyte retention rate and interfacial adhesion. • The cell with the separator exhibited outstanding electrochemical performance. [ABSTRACT FROM AUTHOR]

The safety issues of lithium batteries caused by liquid organic electrolyte have been driving people to seek safer solid-like electrolytes. Herein, we report effort to employ Polyurethane acrylate (PUA) elastomer and Succinonitrile (SN)-based plastic crystal electrolyte (PCE) to fabricate a composite PCE (CPCE) by solution blending followed by rapid UV curing. During fabrication process, the phase separation between PUA and SN-based PCE can be suppressed by adding Tetrahydrofuran (THF). Consequently, the improved compatibility results in an improved mechanical strength in the CPCE and makes PUA impart the good stretching and resilient properties to the CPCE. The optimized CPCE presents a maximum stretching strain of 90.6% and can bear cyclic stretching-releasing test. Besides, the CPCE exhibits a high ionic conductivity of 0.91 × 10 −3 S cm −1 at 30 °C and a wide electrochemical stability window of 4.8 V. Thus, this stretchable CPCE could be used in flexible batteries for emerging applications such as wearable electronic devices and flexible sensors. [ABSTRACT FROM AUTHOR]

Abstract: Interfacial crystallization of polymer on the surface of filler not only offers crystallography interest but also has a potential to improve the interfacial interaction, which is a key for the preparation of high-performance polymer/filler composites. In this work, a new method is proposed to improve the interfacial crystallization between semi-crystalline polymer and glass fiber (GF) by introducing graphene oxide (GO) to the surface of amorphous GF. The coating of GO on GF surface is realized via electrostatic self-assembling of the oppositely charged GO and amino coupling agent modified GF (GF-NH2). After the thermal reduction of the coated GO (RGO), RGO coated GF (GF-RGO) is obtained. The interfacial crystallization of isotactic polypropylene (iPP) and poly(l-lactide) (PLLA) on the surface of raw GF, GF-NH2, and GF-RGO are investigated using Polarized light microscope (PLM). It is found that raw GF and GF-NH2 has almost no nucleation ability on the polymers crystallization. However, transcrystalline structure can be successfully induced at the polymers/GF-RGO interface, indicating a significantly improved nucleation ability of GF-RGO for polymer crystallization. This work could provide a new way to control interfacial crystallization, thus the interfacial adhesion of polymer/filler composites, and could also find a new application for GO as well. [Copyright &y& Elsevier]

Abstract: Periodic patterning of carbon nanotubes (CNTs) with semi-crystalline polymers, especially the novel nanohybrid shish kebab (NHSK) superstructure, in which fibrous CNTs act as shish while polymer lamellae as kebab, is of interest both scientifically and technologically. So far the reported NHSK are mostly prepared using polymers with zigzag conformation in crystal and it seems difficult to obtain NHSK using polymer with helical conformation. In this work, we report the formation of NHSK structure by using single-walled carbon nanotube (SWNT) bundles. A promoted formation of NHSK was observed even using polymer with helical conformation, and the formation mechanism of NHSK was attributed to the unique “groove structure” formed by the stacked SWNTs in parallel arrays, which could facilitate the orientation of helical polymer chains along the SWNTs axis and the lateral formation of stable nucleus. The NHSK structure in helical polymer/SWNT bundles system could widen application of this unique superstructure, offering value in both application field and crystallography aspect as well. [Copyright &y& Elsevier]

• A novel hierarchical SnO 2 -Sn 3 O 4 n-n heterostructure was successfully fabricated through the solvothermal method and subsequent annealing. • The SnO 2 -Sn 3 O 4 heterostructure exhibited excellent NO 2 sensing performance in terms of sensitivity, limit of detection and selectivity. • The formation of SnO 2 -Sn 3 O 4 n-n heterojunction played crucial role in enhancing the sensing performance. Considering the high harmfulness of NO 2 to the environment and human healthy, it is pressing to develop NO 2 sensors with high sensitivity and selectivity. In this work, we successfully fabricated a novel hierarchical SnO 2 –Sn 3 O 4 n–n heterostructure through the solvothermal method and subsequent annealing. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FESEM), and high-resolution transmission electron microscopy (HRTEM) characterization of the material confirmed the hierarchical microsphere structure and the formation of SnO 2 –Sn 3 O 4 n–n heterojunction. The gas sensing experiment demonstrated that the sample annealed at 600 °C exhibited excellent NO 2 sensing performances at 150 °C. Its sensitivities to 5 and 10 ppm NO 2 were as high as 48 and 43.6 ppm−1 respectively, and its limit of detection was lower than 20 ppb. Additionally, it possessed excellent selectivity to NO 2 as well as good repeatability and stability. With further exploration of the sensing mechanism of hierarchical SnO 2 –Sn 3 O 4 n–n heterostructure, we proposed that the unique microstructure with a large specific surface area and the formation of n–n-type heterojunctions contribute to the excellent NO 2 sensing performance. [ABSTRACT FROM AUTHOR]