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The on-demand assembly of 2D heterostructures has brought about both novel interfacial physical chemistry and optoelectronic applications; however, existing studies rarely focus on the complementary part—the 2D cavity, which is a new-born area with unprecedented opportunities. In this study, we have investigated the electric field inside a spacer-free 2D cavity consisting of a monolayer semiconductor and a gold film substrate. We have directly captured the built-in electric field crossing a blinking 2D cavity using a Kelvin probe force microscopy–Raman system. The simultaneously recorded morphology (M), electric field (E), and optical spectroscopy (O) mapping profile unambiguously reveals dynamical fluctuations of the interfacial electric field under a constant cavity height. Moreover, we have also prepared non-blinking 2D cavities and analyzed the gap-dependent electric field evolution with a gradual heating procedure, which further enhances the maximum electric field exceeding 109 V/m. Our work has revealed substantial insights into the built-in electric field within a 2D cavity, which will benefit adventures in electric-field-dependent interfacial sciences and future applications of 2D chemical nanoreactors. [ABSTRACT FROM AUTHOR]

Waterborne polyurethane asphalt emulsion (WPUA) is an environmentally friendly bituminous material, whose performance is highly dependent on the phase structure of the continuous phase. In this paper, WPUAs in the vicinity of phase inversion were prepared using waterborne polyurethane (WPU) and asphalt emulsion. The chemical structures, thermal stability, dynamic mechanical properties, phase-separated morphology and mechanical performance of WPUAs were studied. Fourier-transform infrared (FTIR) spectra revealed that there are no –NCO bonds in either the pure WPU or WPUAs. Moreover, the preparation of WPUA is a physical process. The addition of WPU weakens the thermal stability of asphalt emulsion. WPU improves the storage modulus of asphalt emulsion at lower and higher temperatures. The glass transition temperatures of the WPUA films are higher than that of the pure WPU film. When the WPU concentration increases from 30 wt% to 40 wt%, phase inversion occurs; that is, the continuous phase shifts from asphalt to WPU. The WPUA films have lower tensile strength and toughness than the pure WPU film. However, the elongations at break of the WPUA films are higher than that of the pure WPU film. Both the tensile strength and toughness of the WPUA films increase with the WPU concentration. Due to the occurrence of phase inversion, the elongation at break, tensile strength and toughness of the WPUA film containing 30 wt% WPU are increased by 29%, 250% and 369%, respectively, compared to the film with 40 wt% WPU. [ABSTRACT FROM AUTHOR]

This paper deals with the impact of polymer loading on the microstructure, viscosity, thermal properties and mechanical performance of recycled polyethylene (rPE) modified epoxy asphalt binder. With this aim, rPE was used as a modifier to improve the toughness of a hot-mix epoxy asphalt binder. rPE particles were found to be highly swollen by the asphalt. Double phase separation was observed in rPE modified epoxy asphalt binders: asphalts dispersed in the continuous epoxy phase and rPE particles distributed in the discontinuous asphalt phase. The viscosity of epoxy asphalt binders increased with more rPE contents but the allowable construction time for pavement remained long. Results revealed that the thermal stability of epoxy asphalt binders was slightly improved with the addition of rPE. Furthermore, rPE lowered the glass transition temperature and increased the storage modulus at the rubbery state. All rPE modified epoxy asphalt binders performed better damping behaviours. In addition, at low rPE concentrations, the mechanical properties of epoxy asphalt binders were improved while at rPE loading higher than 2%, the results were opposite. [ABSTRACT FROM AUTHOR]

Bisphenol A epoxy resin cured with a mixture of dimerized and trimerized fatty acids is the first epoxy vitrimer and has been extensively studied. However, the cure behavior and thermal and mechanical properties of this epoxy vitrimer depend on the epoxy/acid stoichiometry. To address these issues, epoxy vitrimers with three epoxy/acid stoichiometries (9:11, 1:1 and 11:9) were prepared and recycled four times. Differential scanning calorimetry (DSC) was used to study the cure behavior of the original epoxy vitrimers. The dynamic mechanical properties and mechanical performance of the original and recycled epoxy vitrimers were investigated by using dynamic mechanical analysis (DMA) and a universal testing machine. Furthermore, the reaction mechanism of epoxy vitrimer with different epoxy/acid stoichiometry was interpreted. With an increase in the epoxy/acid ratio, the reaction rate, swelling ratio, glass transition temperature and mechanical properties of the original epoxy vitrimers decreased, whereas the gel content increased. The recycling decreased the swelling ratio and elongation at break of the original epoxy vitrimers. Moreover, the elongation at break of the recycled epoxy vitrimers decreased with the epoxy/acid ratio at the same recycling time. However, the gel content, tensile strength and toughness of the original epoxy vitrimers increased after the recycling. The mechanical properties of epoxy vitrimers can be tuned with the variation in the epoxy/acid stoichiometry. [ABSTRACT FROM AUTHOR]

Sasobit has been widely applied as warm-mix asphalt (WMA) additive in an environment friendly and energy saving pavement construction. Epoxy asphalt (EA) has been extensively used on the pavement of steel bridge decks. In the present paper, Sasobit was introduced into warm-mix epoxy asphalt binder (WEAB) to prepare Sasobit modified WEAB. The effect of Sasobit on the viscosity, thermal, damping and mechanical properties and morphology of the neat WEAB were investigated using various characterisation techniques. Sasobit significantly lowered the viscosity of the neat WEAB and prolonged the operational lifetime for mixture pavement. Sasobit lowered the glass transition temperature of the neat WEAB. Sasobit slightly decreases the damping properties and thermal stability of the neat WEAB. However, Sasobit increased the tensile strength of the neat WEAB. The crystalline network structures of Sasobit formed in asphalts were clearly observed. The lamellar crystalline structure of Sasobit turned to gel-like structure in curly ribbon shape with an increase of the WMA additive contents. Reaction-induced phase separation occurred in the neat WEAB and Sasobit modified WEABs. No crystalline network structures of Sasobit were observed in the dispersed asphalt phase of the modified WEABs. Sasobit decreased the size of asphalt particles in the continuous epoxy phase. [ABSTRACT FROM AUTHOR]

Collision prediction is a fundamental operation for planning motion in dynamic environments. Existing methods usually exploit complex behavior models or use dynamic constraints in collision prediction. However, these methods all assume simple geometry, such as a disc, which significantly limits their applicability. This paper proposes a new approach that advances collision prediction beyond disc robots and handles arbitrary polygons and articulated objects. Our new tool predicts collision by assuming that obstacles are adversarial. Comparing to an online motion planner that replans periodically at fixed time intervals and a planner that approximates obstacle with discs, our experimental results provide strong evidence that the new method significantly reduces the number of replans while maintaining a higher success rate of finding a valid path. Our geometric-based collision prediction method provides a tool for handling highly complex shapes and provides an approach complementary to those methods that consider behavior and dynamic constraints of objects with simple shapes. [ABSTRACT FROM AUTHOR]

Three series of co-graft cationic starch (St)-based flocculants with distinct structural characteristics, namely, charge density (CD), graft-chain length (L), and graft-chain distribution (N), were successfully synthesized through graft copolymerization of [(2-methacryloyloxyethyl) trimethyl ammonium chloride] and acrylamide. These St-based flocculants with different molecular structures were used to flocculate various kaolin suspensions with different initial turbidities and a sodium humate (NaHA) aqueous solution. The experimental results indicated that CD contributed to flocculation evidently, whereas average L and its N were insignificant in experimentally measured ranges. On the basis of phenomenological theory, a second-order polynomial equation was used to further quantitatively analyze the effects of the three structural factors on the flocculation performance of these St-based flocculants, which were fully consistent with the experimental results. Besides, the optimal dose and its corresponding removal rate could be predicted exactly, and the flocculation mechanisms were discussed in detail according to the established models. With the combination of floc properties and zeta potentials, the flocculation mechanisms of these St-based flocculants for flocculation of kaolin suspensions and NaHA aqueous solution were mainly ascribed to charge patching and simple charge neutralization, respectively. These results improve the understanding of the structure–activity relationship of these graft St-based flocculants, which is of significant guidance for the utilization and design of novel flocculants. Image 1 • Three series of starch-based flocculants with various molecular structure was prepared. • Charge density contributed evidently to flocculation. • Average graft-chain length and its distributions contributed insignificantly. • The structure–activity relationship was established using a quantitative equation. • Flocculation mechanisms were thus discussed deeply based on the established model. [ABSTRACT FROM AUTHOR]

Epoxy asphalt adhesive (EAA) is a thermosetting polymer modified asphalt that has been widely applied on steel bridge decks as a strong adhesive and waterproof layers. In this study, the influence of the asphalt penetration grade on the viscosity, damping and mechanical properties, bond strength, and microstructures of EAAs was investigated. The viscosity of the EAAs increased with increasing asphalt penetration grade. The presence of base asphalt increased the glass‐transition temperature (Tg) of the neat epoxy. The asphalt penetration grade had a negligible effect on the Tg values of the EAAs. The existence of base asphalt improved the damping behaviors of the neat epoxy. Moreover, the damping properties of the EAAs increased with increasing asphalt penetration grade. The tensile strength, elongation at break, and bond strength values of the EAAs increased with increasing asphalt penetration grade. The bond strengths of the EAAs were 7‐ to 10‐fold higher than that of the neat asphalt. The asphalt penetration grade had a negligible effect on the bond strengths of the EAAs. Morphological observations revealed that the average size of the dispersed asphalt particles in the epoxy decreased with increasing asphalt penetration grade. A more homogeneous phase separation was formed in the EAA with a higher penetration‐grade asphalt. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47027. [ABSTRACT FROM AUTHOR]

Epoxy asphalt adhesive (EAA) has been widely used as strong waterproof-bonding layers for the orthotropic steel bridge decks in China. This research employs attapulgite (ATT), one kind of natural fibrous nanoclays, as the nanofiller to reinforce EAA. The crystalline structure, rheological property, thermal stability, mechanical properties and morphology of EAA/ATT composites were investigated by X-ray diffraction (XRD), Brookfield rotational viscometer, thermogravimetric analyzer (TGA), universal test machine and scanning electron microscopy (SEM). Results showed the existence of ATT did not change the noncrystalline structure of the EAA. ATT had a significant decrement effect on the rotational viscosity of EAA. Moreover, the viscosity of EAA/ATT composites decreased with the increasing content of ATT at a specific cure time. The addition of ATT improved thermal stability of the neat EAA. In addition, the incorporation of ATT increased the tensile and adhesive properties of the neat EAA. The tensile strength, toughness, Young's modulus and adhesive strength of EAA/ATT composites increased with the increase of ATT loadings. [ABSTRACT FROM AUTHOR]

As one of polymer modified asphalts (PMAs), epoxy asphalt (EA) has been extensively used in the pavement of steel bridge deck due to its excellent performances. Ethylene vinyl acetate copolymer (EVA) is one of most used polymer modifiers in PMAs. EA/EVA blends were prepared with the addition of EVA in asphalts. The effects of EVA on the morphology evolution of EA were investigated by laser scanning confocal microscopy (LSCM) and scanning electron microscopy (SEM). Furthermore, the rotational viscosity, thermal stability and mechanical properties of EA/EVA blends were studied. LSCM observed that epoxy resin was the continuous phase and EVA-asphalt was the disperse phase in EA/EVA blends. The presence of epoxy crosslinking network destroyed the physical interaction between EVA and asphalts. Both LSCM and SEM observations found that smaller and well-distributed EVA-asphalt particles formed in EA/EVA blends with lower EVA loadings. However, EVA-asphalt particles distributed inhomogeneously in the blends with higher EVA loadings. The addition of EVA increased the viscosity of the neat EA. Moreover, the presence of EVA improved both thermal stability and mechanical properties of the neat EA. [ABSTRACT FROM AUTHOR]

• Thermal shock significantly increases the pull-off strength of the touch-dry BEBC. • The hydrophilic touch-dry BEBC becomes hydrophobic after the thermal shock. • Thermal shock greatly increases the T g of the touch-dry BEBC. • The touch-dry BEBC's tensile strength increases by about 300% after the thermal shock. • Thermal shock temperature has a limited effect on the mechanical properties of BEBCs. B-staged epoxy bond coat (BEBC) has been widely applied as a waterproof adhesive layer in the pavements of orthotropic steel bridges. During its application, the uncured BEBC layer was first paved on the surface of the steel deck or the bituminous surfacing and hot bituminous mixture would be constructed until the BEBC layer became touch-dry. In this paper, the impacts of thermal shock on the degree of cure (DOC), pull-off strength, hydrophilicity, glass transition temperature (T g), damping performance, thermal stability and mechanical behaviors of the touch-dry BEBC were investigated. Thermal shock greatly increased the DOC of the touch-dry BEBC and the touch-dry BEBC turned to be nearly fully cured after the thermal shock at a higher temperature. The pull-off strength of the touch-dry BEBC was remarkably improved by the thermal shock. After the thermal shock at 160 °C, the pull-off strengths at room temperature and at 60 °C of the touch-dry BEBC were increased by 584% and 914%, respectively. After the thermal shock, the contact angle of the touch-dry BEBC was greatly increased and the hydrophilicity of the touch-dry BEBC was converted to hydrophobicity. Thermal shock significantly increased the T g of the touch-dry BEBC. Furthermore, the T g of thermally shocked BEBCs slightly increased in the temperature. Thermal shock improved the damping performance of the fully cured BEBC. The tensile strength and toughness of the touch-dry BEBC were greatly improved by the thermal shock. However, thermal shock lowered the elongation at break of touch-dry BEBC. In the case of thermally shocked BEBCs, the temperature had a limited effect on the tensile strength, while the elongation at break increased in the temperature. The fracture energy first decreased in the temperature and increased after 150 °C. Maximum fracture energy appeared at 160 °C. After the thermal shock, the tensile strength of the touch-dry BEBC was increased by as much as 3-fold. The fracture energy of the BEBC thermally shocked at 160 °C was 182% greater than that of the touch-dry BEBC. [ABSTRACT FROM AUTHOR]

[Display omitted] • Eco-friendly fire-retarded warm-mix epoxy asphalt binders (WEABs) have been developed. • RPFR of significantly improved the fire retardancy of the pure WEAB. • RPFR hinders WEAB's cure reaction and extends the allowable construction time of WEAB mixtures. • RPFR improves the glass transition temperature and thermal stability of the pure WEAB. • Double phase separation forms in RPFR modified WEABs. Epoxy asphalt binder is flammable and plenty of fumes are produced during its high-temperature pavements in tunnels. To improve fire retardancy and reduce asphalt fumes, eco-friendly flame-retarded warm-mix epoxy asphalt binders (WEABs) for road tunnel pavements were developed by incorporation of reactive polymeric flame retardant (RPFR), which was composed of a reactive polymeric brominated epoxy oligomer (BEO) and antimony oxide. The influence of RPRF on flame retardancy, rotational viscosity, microstructures, thermal properties and mechanical performance of the pure WEAB was investigated using various techniques: oxygen index instrument, Brookfield viscometer, confocal microscope, differential scanning calorimeter, thermogravimetric analyzer and universal testing machine. The presence of RPFR significantly improved the limited oxygen index (LOI) of the pure WEAB. The LOI of RPFR modified WEABs increased in the flame retardant loading. The reaction of epoxide groups of RPFR with the curing agents of epoxy asphalt reduced the viscosity of the pure WEAB and extended the allowable construction time of the WEAB mixture. The inclusion of RPFR increased the glass transition temperature (T g) of the pure WEAB. For modified WEABs, the T g increased in the RPFR loading. RPFR reacted into the epoxy asphalt backbone through the reaction between epoxy groups and curing agents. The incorporation of RPFR improved the thermal stability of the pure WEAB. The addition of 8 wt% RPFR increased the tensile strength of the pure WEAB, while the inclusion of RPFR slightly decreased the break elongation of the pure WEAB. Double phase separation occurred in RPFR modified WEAB: the main phase separation included the continuous epoxy phase and the discontinuous asphalt domains, in which the secondary phase separation formed with asphalt as the continuous phase and spherical BEO domains as the discontinuous phase. The particle size of BEO domains decreased with the increase of the RPFR loading. [ABSTRACT FROM AUTHOR]

• A series of actinia-shaped lignin-based adsorbent (LNAEs) was designed and fabricated. • The prepared LNAEs were applied to remove ofloxacin and ciprofloxacin from water. • Electrostatic attraction and hydrogen bonding were mainly involved in this adsorption. • Adsorption mechanisms were revealed from graft-chain length and distribution of LNAEs. • Structure-activity relationship of this adsorbent was built using a simple model. A series of actinia-shaped lignin-based adsorbents (LNAEs) featuring lignin(LN) as the core and grafted poly(acrylic acid) (PAA) as the tentacle were designed and fabricated. LNAEs were applied to remove ofloxacin and ciprofloxacin from water, and their maximum adsorption capacities were 0.835 and 0.965 mmol/g at pH 6.0, respectively. However, their adsorption capacities were up to about 20 % and 31 % reductions in the present of NaCl and humic acid, respectively. Electrostatic attraction (EA) and hydrogen bonding (HB), including ordinary HB and negative charged auxiliary HB, were mainly involved in adsorption. Experimental and calculation results indicated HB contributes more than EA. The effects of two structural factors of LNAEs, namely, PAA branched-chain length(L) and distribution density(D), on the adsorption performance associated with HB and EA, were quantitatively discussed using a binary nonlinear model based on phenomenological theory. The fitting results were completely consistent with the experimental findings. D was more efficient than L in promoting HB and EA in adsorption due to the cooperative effects of adjacent branched-chains and enhanced activity of terminal groups. This study provides a better understanding of the structure–activity relationship of surface grafting-modified adsorbents and fundamental guidance for the exploitation and design of novel and efficient adsorbents. [ABSTRACT FROM AUTHOR]

In this work, a simple and environmentally-friendly enhanced coagulation, by using a cationic starch-based coagulant (starch-3-chloro-2-hydroxypropyl trimethyl ammonium chloride, St-CTA) coupled with an optimized polysilicic acid (PSA), has been tried to coagulate the kaolin suspensions and humic acid (HA) aqueous solutions, which are used as the simulated sources of inorganic colloidal particles and organic pollutant, respectively, in micro-polluted turbid surface water. Dosing of St-CTA and PSA at the same time is more efficient and more convenient than other two separated feeding methods in this enhanced coagulation process. The synergic coagulation process and mechanism were studied and discussed in detail based on the apparent coagulation performance, floc properties, and zeta potentials of supernatants. St-CTA caused an efficient charge neutralization, i.e. compression of electric double layer of kaolin particles and electrostatic adsorption of HA, followed by an effective netting-bridging effect of PSA, resulting in an improved purification performance. St-CTA with a higher charge density showed better purification performance due to enhanced charge neutralization effect. In addition to simulated water, the validation of this enhanced coagulation process was further confirmed by comparison with a conventional coagulant, polyaluminium chloride, in treating a real surface water. This work thus provides a simple and environmentally-friendly strategy to efficiently purify micro-polluted turbid surface water and further improve the water safety. Image 1 • An enhanced coagulation is provided by a cationic starch aided with polysilicic acid. • This strategy effectively purifies the micro-polluted turbid surface water. • Two agents dosed together show highly efficient purification performance. • Charge neutralization and netting-bridging effects play important roles. • The validation of this enhanced coagulation is confirmed by treating a real water. [ABSTRACT FROM AUTHOR]

We propose an algorithmic framework of a pluripotent structure evolving from a simple compact structure into diverse complex 3D structures for designing the shape-transformable, reconfigurable, and deployable structures and robots. Our algorithmic approach suggests a way of transforming a compact structure consisting of uniform building blocks into a large, desired 3D shape. Analogous to a fertilized egg cell that can grow into a preprogrammed shape according to coded information, compactly stacked panels named the zygote structure can evolve into arbitrary 3D structures by programming their connection path. Our stacking algorithm obtains this coded sequence by inversely stacking the voxelized surface of the desired structure into a tree. Applying the connection path obtained by the stacking algorithm, the compactly stacked panels named the zygote structure can be deployed into diverse large 3D structures. We conceptually demonstrated our pluripotent evolving structure by energy-releasing commercial spring hinges and thermally actuated shape memory alloy hinges, respectively. We also show that the proposed concept enables the fabrication of large structures in a significantly smaller workspace., (© The Author(s) 2023. Published by Oxford University Press on behalf of National Academy of Sciences.)

Solar-driven nitrogen fixation is a promising clean and mild approach for ammonia synthesis beyond the conventional energy-intensive Haber-Bosch process. However, it is still challenging to design highly active, stable, and low-cost photocatalysts for activating inert N 2 molecules. Herein, we report the synthesis of anatase-phase black TiO 2- x S y nanoplatelets enriched with abundant oxygen vacancies and sulfur anion dopants ( V O -S-rich TiO 2- x S y ) by ion exchange method at gentle conditions. The V O -S-rich TiO 2- x S y nanoplatelets display a narrowed bandgap of 1.18 eV and much stronger light absorption that extends to the near-infrared (NIR) region. The co-presence of oxygen vacancies and sulfur dopants facilitates the adsorption of N 2 molecules, promoting the reaction rate of N 2 photofixation. Theoretical calculations reveal the synergistic effect of oxygen vacancies and sulfur dopants on visible-NIR light adsorption and photoexcited carrier transfer/separation. The V O -S-rich TiO 2- x S y exhibits improved ammonia yield rates of 114.1 μmol g -1 h -1 under full-spectrum irradiation and 86.2 μmol g -1 h -1 under visible-NIR irradiation, respectively. Notably, even under only NIR irradiation (800-1100 nm), the V O -S-rich TiO 2- x S y can still deliver an ammonia yield rate of 14.1 μmol g -1 h -1 . This study presents the great potential to regulate the activity of photocatalysts by rationally engineering the defect sites and dopant species for room-temperature N 2 reduction.

This study starts from the counterintuitive question of how we can render conventional stiff, nonstretchable, and even brittle materials sufficiently conformable to fully wrap curved surfaces, such as spheres, without failure. Here, we extend the geometrical design method of computational origami to wrapping. Our computational wrapping approach provides a robust and reliable method for fabricating conformal devices for arbitrary curved surfaces with a computationally designed nonpolyhedral developable net. This computer-aided design transforms two-dimensional (2D)-based materials, such as Si wafers and steel sheets, into various targeted conformal structures that can fully wrap desired 3D structures without fracture or severe plastic deformation. We further demonstrate that our computational wrapping approach enables a design platform that can transform conventional nonstretchable 2D-based devices, such as electroluminescent lighting and flexible batteries, into conformal 3D curved devices., (Copyright © 2020 The Authors, some rights reserved; exclusive licensee American Association for the Advancement of Science. No claim to original U.S. Government Works. Distributed under a Creative Commons Attribution NonCommercial License 4.0 (CC BY-NC).)