The presence of supramolecular interactions plays a crucial role in the formation of resilient multifunctional elastomers. Nevertheless, achieving elastomers with fabulous mechanical properties remains a significant challenge due to the incomplete understanding of the underlying principles. In this study, we have presented a simple yet efficient approach for manipulating the microstructure, resulting in a significant enhancement of the mechanical properties of the elastomers.
View Article and Find Full Text PDFSmooth metal microspheres with uniform sizes are ideal for constructing particle-arrayed anisotropic conductive films (ACF), but synthesis is hindered by challenges in controlling anisotropic metal growth. Here, we present a positioned transient-emulsion self-assembly and laser-irradiation strategy to fabricate pure gold microsphere arrays with smooth surfaces and uniform sizes. The fabrication involves assembling gold nanoparticles into uniform colloidosomes within a pre-designed microhole array, followed by rapid transformation into well-defined microspheres through laser heating.
View Article and Find Full Text PDFCorrosion inhibitor additives are considered to be one of the effective methods to slow down the corrosion of metals, but the corrosion inhibitors will decompose and lose their effect in a long-term corrosive environment. In this work, a smart corrosion inhibitor carrier 2-mercaptobenzimidazole-Zn-polydopamine@graphite (MZPG) with excellent pH response was designed and synthesized using a one-pot method. This corrosion inhibitor carrier not only has a very high 2-mercaptobenzimidazole (MBI) loading capacity (38.
View Article and Find Full Text PDFAu nanotube-based composite membrane served as surface-enhanced Raman scattering (SERS) substrate with an ultralarge aspect ratio possesses an excellent flexibility and widely tunable surface plasmon resonance, and by introducing graphene oxide (GO) as a spacer layer, the SERS enhancement of the composite membrane is obviously better than those from the individual blocks of the Au nanotubes (AuNTS) membrane and the Au nanoparticle/graphene oxide (AuNP/GO) membrane. Such a "sandwich" (AuNP/GO/AuNT) structured membrane has a high SERS sensitivity and a wide tunability by controlling the size of Au nanoparticles and the thickness of graphene oxide, and the detection limits of the AuNP/GO/AuNT substrate for R6G and NBA are as low as 10 and 10 M, respectively; the large enhancement is attributed to the adsorption and chemical mechanism of graphene oxide and the physical mechanism of the Au nanoparticles and nanotubes (the electromagnetic field coupling between them).
View Article and Find Full Text PDFPerovskite solar cells with the formula FACsPbI, where FA is formamidinium, provide an attractive option for integrating high efficiency, durable stability and compatibility with scaled-up fabrication. Despite the incorporation of Cs cations, which could potentially enable a perfect perovskite lattice, the compositional inhomogeneity caused by A-site cation segregation is likely to be detrimental to the photovoltaic performance of the solar cells. Here we visualized the out-of-plane compositional inhomogeneity along the vertical direction across perovskite films and identified the underlying reasons for the inhomogeneity and its potential impact for devices.
View Article and Find Full Text PDFDue to their mechanical flexibility, conductive hydrogels have been widely investigated in the fields of flexible electronics and soft robots, but their non-negligible disadvantages, such as poor toughness and limited self-healing, severally restrict their practical application. Herein, gallium indium alloy (EGaIn) is utilized to initiate the polymerization and simultaneously serve as flexible fillers to construct a super-stretchable and self-healing liquid metal/polyvinyl alcohol/(acrylamide--octadecyl methacrylate) (liquid metal/PVA/P(AAm--SMA)) double network hydrogel (LM hydrogel). The synergistic effect of the rigid PVA microcrystal network and the ductile P(AAm--SMA) hydrophobic network, together with the ionic coordination and hydrogen bonds between polymer networks (multiple physical cross-links), endow the LM hydrogel with excellent super-stretchability (2000%), toughness (3.
View Article and Find Full Text PDFNext-generation wearable electromagnetic interference (EMI) materials need to be provided with oxidation resistance, lightness, and flexibility. In this study, a high-performance EMI film with synergistic enhancement of Zn@TiCT MXene/cellulose nanofibers (CNF) was found. The unique Zn@TiCT MXene/CNF heterogeneous interface facilitates the loss of interface polarization, making the total electromagnetic shielding effectiveness (EMI SE) and shielding effectiveness per unit thickness (SE/) of the films reach 60.
View Article and Find Full Text PDFMixed lead-tin (PbSn) perovskite solar cells (PSCs) possess low toxicity and adjustable bandgap for both single-junction and all-perovskite tandem solar cells. However, the performance of mixed PbSn PSCs still lags behind the theoretical efficiency. The uncontrollable crystallization and the resulting structural defect are important reasons.
View Article and Find Full Text PDFOrganic shell material and phase change material (PCM) have low thermal conductivity, which reduces the heat absorption and release rate of microencapsulated phase change materials (MEPCMs). Boron nitride nanosheets (BNNSs) with high thermal conductivity can not only stabilize the oil phase as the Pickering emulsifier but also improve the thermal conductivity of MEPCMs as one of the shell components, thus facilitating the heat conduction in the microcapsule system. Herein, MEPCM with paraffin wax (PW) as the core material and polystyrene (PS) modified by BNNSs as the shell material (PW@PS/BNNS MEPCMs) are synthesized via Pickering emulsion polymerization.
View Article and Find Full Text PDFSurface modification of hexagonal boron nitride (h-BN) has the problem of reducing the interfacial thermal resistance, which has hindered its application in thermal conductive composites. Herein, poly glycidyl methacrylate (PGMA) chains were grafted onto the h-BN surface by simple radical polymerization; the thermal conductivity of epoxy (EP) composites was improved by adding the as-grafted h-BN-PGMA to EP resin. When the filling volume of h-BN-PGMA was 4, 10 or 16 vol%, the thermal conductivity of EP composite increased by 160%, 298% or 599%, respectively.
View Article and Find Full Text PDFLiquid metals (LMs) are playing an increasingly important role in the fields of flexible devices, electronics, and thermal management due to their low melting point and excellent thermal and electrical conductivity, and the transformation of LMs in deionized water has recently received much attention. In this paper, we investigate the transformation process of EGaIn microspheres in deionized water and propose a two-step process of microspherical transformation, whereby the microspheres are first deformed into a spindle shape and then into lamellar nanorods. It is also shown that the growth of GaOOH crystals drives the transformation.
View Article and Find Full Text PDFColloidal molecules (CMs), nonspherical clusters of a small number of particles, can be used as building blocks for self-assembly applications. Here, we propose a novel one pot method for CMs synthesis. First, poly(-isopropylacrylamide--acrylic acid) (P(NIPAM--AA)) microgels were prepared by soap-free emulsion polymerization as seed particles, then monomer styrene and cross-linking agent divinylbenzene (DVB) were added, which could be polymerized by the remaining free radicals on the seed surface in situ.
View Article and Find Full Text PDFDespite ceaseless efforts in past decades, the memory effect of semi-crystalline polymers has not been elucidated completely yet. An important reason why is that residual lamellar crystals in the structured melt are difficult to characterize. Recently, we developed a new small-angle X-ray scattering (SAXS) theory [Li (2019).
View Article and Find Full Text PDFThree-dimensional Au network films with flexibility and transferability were fabricated based on sputtering deposition onto electrospun nanofibers as a template. The films are constructed using long Au nanotubes that are cross-linked with each other and that have dense nanoparticles on the tube wall surface. The surface plasmon resonance (SPR) peaks for the films are tunable in a wide range, from visible light to the near-infrared region, by tuning the inner diameter and/or wall thickness of the nanotubes.
View Article and Find Full Text PDFDriven by the evolution of electronic packaging technology for high-dense integration of high-power, high-frequency, and multi-function devices in modern electronics, thermal management materials have become a crucial component for guaranteeing the stable and reliable operation of devices. Because of its admirable in-plane thermal conductivity, graphene is considered as a desired thermal conductor. However, the promise of graphene films has been greatly weakened as the existence of grain boundaries lead to a high extent of phonon scattering.
View Article and Find Full Text PDFSelf-healable polyurethanes can be used in various fields for extended service life and reduced maintenance costs. It is generally believed that the shape memory effect is helpful for achieving a high healing efficiency. The morphological features were focused on in this study as microphase separation is one of the main factors affecting various performances of polyurethanes, including their shape memory behavior and mechanical properties.
View Article and Find Full Text PDFAs the temperature of hot spots increases in electronic devices, thermal management is a key issue for maintaining a device's reliability and performance. The usual approaches of quickly extracting the heat from the hot spots have focused on aligning two-dimensional filler along the in-plane orientation in the polymer matrix. Meanwhile, improving the through-plane thermal conductivity of polymer-based composites is as important as in-plane thermal conductivity.
View Article and Find Full Text PDFACS Appl Mater Interfaces
November 2019
Thermally conductive polymer packaging material is of great significance for the thermal management of electronics. Inorganic thermally conductive fillers have been demonstrated as a convenient approach to achieve this goal by sacrificing the lightweight and processability of the polymer. To address this problem, an effective 3D boron nitride (BN) network was constructed as a heat conduction pathway in a polystyrene (PS) matrix based on an oil-water interface assembly in this work.
View Article and Find Full Text PDFAs is well known, polymers commonly form lamellar crystals, and these assemble further into lamellar stacks and spherulites during quiescent crystallization. Fifty years ago, Vonk and Kortleve constructed the classical small-angle X-ray scattering theory (SAXS) for a lamellar system, in which it was assumed that the lamellar stack had an infinite lateral size [Vonk & Kortleve (1967 ▸), , 19-24]. Under this assumption, only crystal planes satisfying the Bragg condition can form strong scattering, and the scattering from the lamellar stack arises from the difference between the scattering intensities in the amorphous and crystalline layers, induced by the incident X-ray beam.
View Article and Find Full Text PDFPhotocatalytic hydrogen production from water exhibits great potential for solar energy conversion. In this work, using monoclinic CaInS with a surface nanostep structure as a model photocatalyst, we demonstrate a facile and efficient strategy for the construction of AO /AuCu/CaInS (A = Mn, Ni, and Pb) composites by site-selective photodeposition of the reductive cocatalyst AuCu alloy and oxidative cocatalyst AO on the edge and groove sites of CaInS nanosteps, respectively. Compared to single-cocatalyst composites (AuCu/CaInS and AO /CaInS) and CaInS, the simultaneous deposition of AuCu and AO spatially separate the photogenerated charges and the photocatalytic reaction sites, therefore effectively improving the separation efficiency of charge carriers.
View Article and Find Full Text PDFThe orientation of ultrahigh aspect ratio thermally conductive fillers can construct a heat transfer path to enhance the thermal conductivity of composite materials effectively with low filler loading. Nevertheless, single orientation (vertical or horizontal) limited the application of these materials when there was the need for isotropic heat transferring. Here we report a novel strategy to prepare thermally conductive flexible cycloaliphatic epoxy resin nanocomposites with an oriented three-dimensional staggered interconnected network of vertically aligned h-BN (hexagonal boron nitride) platelets and randomly dispersed CNT-NH (aminated carbon nanotubes).
View Article and Find Full Text PDFThis article studied the influence of silica (SiO2) particles on the crosslinked network and the molecular mobility of ethylene-propylene-diene (EPDM) rubber chains by dynamic mechanical analysis (DMA). When SiO2 fraction is lower than 8 phr, the chain segments that participate in the glass-rubber transition (α transition) decrease with increasing the SiO2 content, while the whole crosslinked network is almost unaffected by the presence of SiO2. When the SiO2 fraction increases to about 20 phr, there appears a new tan δ peak (α' transition) above the α transition.
View Article and Find Full Text PDFThe effects of polydimethylsiloxane (PDMS) on phase separation, optical transmittance and surface properties including surface composition, morphology and wettability of waterborne polyurethane (WPU) containing PDMS were investigated. After the introduction of PDMS into the WPU backbone by polymerization, the large difference in the solubility parameter of the non-polar PDMS segment and the high-polar urethane segments promoted PDMS enrichment at the air-polymer interface and enhanced phase separation, resulting in rough structures. Accordingly, the combination of PDMS enrichment and the rough structures contributed to the high or superhydrophobic surfaces and the highest contact angle with water achieved was 156.
View Article and Find Full Text PDFMultifunctional graphene hydrogels have attracted great attention aimed at practical applications. Herein, the novel and bifunctional composite hydrogel containing reduced graphene-oxide nanosheets (RGO) and V2O5 nanobelts (RGO/V2O5) is successfully prepared for the first time. Surprisingly, tridimensional (3D) RGO/V2O5 composite hydrogels cannot only be used as high-performance electromagnetic (EM) wave absorbents; they also exhibit excellent properties suitable for supercapacitor electrodes.
View Article and Find Full Text PDFGraphene oxide (GO) nanosheets and polyoxometalate such as H(3)PW(12)O(40) (PTA) are prepared into a multilayer film via a layer-by-layer inkjet printing method. The GO/PTA composite thin film shows linear, uniform and regular layer-by-layer growth. Under UV-irradiation, a photoreduction reaction takes place in the film which converts GO to reduced GO (rGO) due to the photoreduction activity of polyoxometalate clusters.
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