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Three-dimensional-printed silicone rubber foams, with their designable and highly ordered pore structures, have shown exceptional potential for engineering applications, particularly in areas requiring energy absorption and cushioning. However, optimizing the mechanical properties of these foams through structural design remains a significant challenge. This study addresses this challenge by formulating the research question: How do different 3D-printed topologies and printing parameters affect the mechanical properties of silicone rubber foams, and how can we design a novel topological structure? To answer this, we explored the mechanical behavior of two common structures–simple cubic (SC) and face-centered tetragonal (FCT)–by varying printing parameters such as filament spacing, filament diameter, and layer height. Furthermore, we proposed a novel two-level 3D-printed structure, combining SC and FCT configurations to enhance performance. The results demonstrated that the two-level SC-SC structure exhibited a specific energy absorption of 8.2 to 21.0 times greater than the SC structure and 2.3 to 7.2 times greater than the FCT structure. In conclusion, this study provides new insights into the design of 3D-printed silicone rubber foams, offering a promising approach to developing advanced cushioning materials with superior energy absorption capabilities. [ABSTRACT FROM AUTHOR]

Silicone rubber molds were treated with air plasma and used to prepare polyvinyl alcohol/polyvinylpyrrolidone water-soluble microneedles. The effects of plasma treatment on mold wettability, coating adhesion, micro-needle yield and mechanical properties were discussed. The results showed that plasma treatment could generate polar hydrophilic groups on the surface of the mold, improve the wettability of the mold, the adhesion of polyvinyl alcohol/polyvinylpyrrolidone coating, and elevate the yield rate of micro-needles and the overall mechanical properties. With the prolongation of plasma treatment time, the wettability of the mold, the yield rate of microneedles and the mechanical properties increased increased and then decreased. When the silicone rubber mold was treated with air plasma for 6-8 minutes, water-soluble microneedles with a complete structure, good mechanical property and easy demolding ability could be prepared. [ABSTRACT FROM AUTHOR]

Highlights: A fully self-powered bimodal sensor is designed for patterned-displaying the force trajectories. Outstanding mechanoluminescence is achieved with a stimulation force as low as 0.3 N and 2000 cycles reproducibility. The designed bimodal sensor exhibits good potential for handwriting input to achieve visual intelligent control. Self-powered flexible devices with skin-like multiple sensing ability have attracted great attentions due to their broad applications in the Internet of Things (IoT). Various methods have been proposed to enhance mechano-optic or electric performance of the flexible devices; however, it remains challenging to realize the display and accurate recognition of motion trajectories for intelligent control. Here, we present a fully self-powered mechanoluminescent-triboelectric bimodal sensor based on micro-nanostructured mechanoluminescent elastomer, which can patterned-display the force trajectories. The deformable liquid metals used as stretchable electrode make the stress transfer stable through overall device to achieve outstanding mechanoluminescence (with a gray value of 107 under a stimulus force as low as 0.3 N and more than 2000 cycles reproducibility). Moreover, a microstructured surface is constructed which endows the resulted composite with significantly improved triboelectric performances (voltage increases from 8 to 24 V). Based on the excellent bimodal sensing performances and durability of the obtained composite, a highly reliable intelligent control system by machine learning has been developed for controlling trolley, providing an approach for advanced visual interaction devices and smart wearable electronics in the future IoT era. [ABSTRACT FROM AUTHOR]

Structural metamaterial with negative Poisson's ratio often has low stiffness due to its porous structure. For engineering applications, the various strategies have been developed to enhance its stiffness but also weaken the negative Poisson effect. In this work, we propose a 3D reinforced re-entrant structure (RRS) by adding arrow structures to the classical re-entrant structure (RS), which is fabricated by photocuring 3D printing of photosensitive resin. The structure-properties correlative mechanism of RRS is systematically analyzed by combining experiment (quasi-static compression experiment) and finite element simulation (ABAQUS). It is found that the equivalent elastic modulus and negative Poisson's ratio of RRS can be tuned by various structural parameters (i.e. the thickness ratio η, the length ratio of the slant rod α, the length ratio of the vertical rod β, and the angle θ of the re-entrant cells). By optimizing the structure parameters, the equivalent elastic modulus of RRS with the negative Poisson's ratio of −0.28 can be significantly increase to 13.67 MPa, which is 12.32 times larger than that of RS with the same negative Poisson's ratio. Due to the flexible design of stiffness and negative Poisson ratio, our proposed 3D reinforced re-entrant structural metamaterial provides a potential way for designing engineering materials with desirable performance. [ABSTRACT FROM AUTHOR]

Ti2 Nb 1 0 O 2 9 (TNO) is considered as a potential anode material due to its high capacity/power density and reliable safety. However, its poor electronic conductivity restricts its rate performance, which is important for its application in electric vehicles (EVs). In this study, we fabricated a hybrid of Ti2 Nb 1 0 O 2 9 − x /holey-reduced graphene oxide (TNOx/HRGO) by a two-step method. In the structure of TNOx/HRGO, TNOx microspheres with oxygen vacancies are wrapped by gossamer-like HRGO. The oxygen vacancies of TNOx and the high conductivity of HRGO can effectively enhance the electronic conductivity of the TNOx/HRGO hybrid, and the HRGO holes are beneficial for the transmission of lithium-ion ( Li + ). The synergy effect of above features improves the rate performance of the TNOx/HRGO hybrid. In addition, the existence of HRGO can buffer volume expansion during the insertion processes of Li + , which can improve cyclic stability of the TNOx/HRGO hybrid. Consequently, the TNOx/HRGO electrode has excellent lithium-ion storage capacity, with high-rate performance (242 mAh/g at 10∘C, 225 mAh/g at 20∘C and 173 mAh/g at 40∘C) and excellent cyclic stability (98.0% capacity retention after 300 cycles at 10∘C). This work reveals that TNOx/HRGO can be a potential anode material for high-rate-performance lithium-ion storage. TNOx/HRGO hybrid was fabricated through solvothermal method, annealing, and freeze-drying, and its performance as anode of LIB was investigated. Due to its porous microstructure, the existence of oxygen vacancies and holey-reduced graphene oxide coating, the electronic conductivity and ionic conductivity of TNOx/HRGO were greatly improved, thus obtaining excellent high-rate performance. [ABSTRACT FROM AUTHOR]

Although bulk superhydrophobic materials are considered as promising candidates because of their durable anti-wetting properties, they still face some challenges such as complicated fabrication processes and inherent brittleness. In the present study, we prepared a robust and flexible bulk superhydrophobic film by a facile “UV curing + solvent evaporation” method. Using this method, a cross-linked organic gel is generated by rapid thiol–ene photopolymerization (within 60 s) of a polydimethylsiloxane (PDMS)/hydrophobic silica/cyclohexane suspension and is further transformed into a superhydrophobic porous film after solvent evaporation. With the optimized solvent/polymer mass ratio (15 : 1), the superhydrophobic PDMS/silica film shows high stretchability (∼68%) and solid mechanical strength because of the appropriate cross-linking degree and low porosity of the polymer skeleton. The silica particles and porous structure cooperatively form self-similar and hierarchical structures across the film bulk, which can be repetitively exposed to the surface by abrasion to maintain durable superhydrophobicity. Consequently, the robustness and regenerative characteristics of the hierarchical structure enable the film to maintain durable superhydrophobicity while facing various mechanical damages such as 1000 cycles of stretching–releasing and 500 abrasion cycles. Taking advantage of the regenerative characteristics, the damaged superhydrophobic film surface is rapidly recovered by sanding treatment without the use of healing agents. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to provide additive manufacturing-based solutions for preparation of elastomeric foam with broaden compressive stress plateau.Design/methodology/approach Mechanic models are developed for obtaining designs of foam cell units with enhanced elastic buckling. An experimental approach is taken to fabricate the foams based on direct ink writing technique. Experimental and simulation data are collected to assist understanding of our proposals and solutions.Findings A simple tetragonal structured elastomeric foam is proposed and fabricated by direct ink writing, in which its cell unit is theoretically designed by repeating every four filament layers. The foam exhibits a broader stress plateau, because of the pronounced elastic buckling under compressive loading as predicted by the authors’ mechanic modeling. A two-stage stress plateaus as observed in the foam, being attributed to the dual elastic buckling of the cell units along two lateral directions of the XY plane during compression.Research limitations/implications Future work should incorporate more microscopic parameters to tune the elastomeric foam for mechanic performance testing on linear elastic deformation and densification of polymer matrix.Practical implications Additive manufacturing offers an alternative to fabricate elastomeric foam with controlled cell unit design and therefore mechanics. Our results comment on its broad space for development such superior cushioning or damping material in the fields of vibration and energy absorption.Originality/value This work has contributed to new knowledge on preparation of high performance elastomeric foam by providing a better understanding on its cell structure, being printed using direct ink writing machines. [ABSTRACT FROM AUTHOR]

Although superhydrophobic porous membranes are considered to be very promising candidates for oil–water separation, their fabrication methods often involve complicated treatments to build a coating with micro/nano-features on a porous mesh (called “coating on a mesh structure”), which can lead to weak mechanical stability of the superhydrophobic surfaces and the formation of inhomogeneous membrane pores. Herein, we report a facile and environmentally friendly 3D printing approach to fabricate superhydrophobic membranes with an ordered porous structure for oil–water separation using hydrophobic nanosilica-filled polydimethylsiloxane (PDMS) ink. The addition of nanosilica can improve the mechanical strength of the ink and thus ensures the formation of desired topographical structures without the risk of collapsing during 3D printing. Through adjusting the geometrical parameters, a superhydrophobic PDMS membrane was obtained, which mainly depended on the roughness at the sub-millimeter scale. More importantly, the 3D printing approach described herein integrated the superhydrophobic surface into the porous framework and resulted in a mechanically durable superhydrophobic membrane, which successfully avoids the weak interface adhesion issue that arises from the traditional “coating on a mesh structure.” Moreover, the pore size of the printed membrane could be easily adjusted via a computer program to optimize both the liquid flux and separation efficiency of the membranes. The maximum oil–water separation efficiency (∼99.6%) could be achieved for the printed porous membrane with the pore size of 0.37 mm, which also exhibited a high flux of ∼23 700 L m−2 h−1. [ABSTRACT FROM AUTHOR]

SERS optrodes were used to “fish” aqueous drops from superhydrophobic surfaces. The technique led to an improvement of 2–3 orders of magnitude in the lowest detectable amount of the Raman probe nile blue A, reaching 25 fg (34 attomoles). Further tests run on samples containing pesticide revealed that 20 pg of triazophos could be clearly detected from a single drop. [ABSTRACT FROM AUTHOR]

A surface enhanced Raman scattering (SERS) substrate, capable of extracting small amounts of organic species from surfaces of different types of materials with variable roughness, has been fabricated. The substrate consists of Ag NPs encapsulated in poly(vinyl alcohol) (PVA) hydrogels, commonly known as PVA “slime”. Unlike traditional SERS substrates, such as colloidal suspensions, the resulting PVA slime SERS substrate presents good viscoelasticity, allowing it to conform to the surface of various materials of arbitrary roughness. Surfaces of different materials, including sandpapers, cotton, metal, and wood, previously contaminated with nile blue A (NBA) were analyzed with the PVA slime SERS substrate. Limits of detection (LOD) as low as 100 ppb (0.79 ng in a total amount on an area of ∼3 cm2) were achieved for all surfaces tested. Pesticides and Sudan red III on the glass surface have also been detected, with a LOD of 1.6 ng per ∼3 cm2. [ABSTRACT FROM AUTHOR]

Enhancing the electrolyte wetting of separators by surface modification is very critical to prepare highperformance lithium-ion batteries. Herein, we present a new approach named hyperthermal hydrogen induced cross-linking (HHIC) technology to increase the electrolyte-affinity of polypropylene (PP) separators by covalently cross-linking a thin layer of poly(ethylene oxide) (PEO) on surface-inert PP separators. With the HHIC treatment, the polar functionalities of PEO (e.g. -OH, C-O-C) can be preserved through selective cleavage of C-H bonds and subsequent cross-linking of resulting carbon radicals generated on PEO and PP chains. As proved by solvent rinsing tests, contact angle measurements and Fourier transform infrared spectroscopy, a PEO coating was found firmly fixed on the separator surface, which results in significantly improved wetting with the electrolyte. Electrochemical measurements on subsequent lithium-ion batteries with the modified separator by HHIC treatment exhibit a lower internal resistance but higher capacity retention when compared to the pristine separator. HHIC treatment is concluded to be a highly efficient and environmental-friendly approach for separator surface modification without need for other chemical additives (e.g. chemical cross-linkers, initiators, and catalysts) and can preserve the desired macroscopic material properties of separators such as pore structures and mechanical strength. [ABSTRACT FROM AUTHOR]

In this study, the early stage of interfacial crystallisation behaviour of low molecular weight polyethylene (PE) and isotactic polypropylene (iPP) oligomer on the surface of carbon nanotubes (CNTs) with different diameters, chiralities and topography structures was studied using MD simulations. We started to simulate the effect of CNTs chirality and diameter on PE molecular chain orientation, and then the effect of CNTs topography structure on PE and iPP molecular chain orientation was investigated. Finally, some experiments were carried out to prove the simulated results. Our study shows that for CNTs with a diameter comparable with the radius of gyration (Rg) of a polymer chain, an easy orientation of PE chains along CNTs axis is observed for all the systems of the CNTs with different chiralities due to a geometric confinement effect. For CNTs with a much larger diameter, multiple orientation of PE chains is induced on its surface due to the lattice matching between graphite lattice and PE molecular chains. In this case, the chirality of CNTs dominates the orientation of graphite lattice, which determines the orientation of PE chains arrangement on CNTs surface. More importantly, it was found that the groove structure formed by CNT bundles is very useful for the stabilisation of polymer chain, and thus facilitates the orientation of molecular chain along the long axis of CNTs. As a result, a novel nanohybrid shish–kebab (NHSK) structure with CNTs acting as central shish while polymer lamellae as kebab can be successfully obtained for both PE with zigzag conformation and iPP with helical conformation. This simulation result was well supported by the experimental observation. Our study could provide not only a deep understanding of the origin of the polymer chain orientation on CNTs surface but also the guidance for the preparation of polymer/CNTs nanocomposites with novel NHSK structure. [ABSTRACT FROM PUBLISHER]

In this work, we report a new approach to resolve a practical problem in producing conductive polystyrene/reduced-graphene-oxide (PS/RGO) composites, i.e. the dilemma that raising the conductivity detrimentally compromises the environmental friendliness of the process because the prevalent chemistry designs emphasize raising conductivity in RGO production by employing strong and toxic chemicals or energy-consuming heat treatments. These designs then rely on organic solvents, chemical functionalization, and stabilizers to overcome the difficulty in dispersing and incorporating RGO into the polymer matrix. In our new design, we emphasize that a compact percolated three-dimensional microcellular RGO network with long-range order is the most effective use of RGO for high composite conductivity. With this guide, GO and non-polar PS mono-dispersed microspheres are co-dispersed in water, with GO stably adsorbing on the microspheres. PS/GO microspheres are then reduced with a nontoxic reducing agent such as vitamin C. PS/RGO microspheres are subsequently hot-pressed into a composite with the required compact percolated three-dimensional microcellular RGO structure. Experimental data collected from the resultant composites validate the design and indeed show low percolation threshold (0.08 vol%), high conductivity (20.5 S m−1), and good compliance with the principles of green chemistry. [ABSTRACT FROM AUTHOR]

Nanohybrid shish kebab (NHSK) structure, in which fibrous carbon nanotubes (CNTs) act as shish, while polymer lamellae as kebab, is of particular interest both scientifically and technologically. In this work, two types of CNTs with the same diameter range and different topography structure, namely multiwalled carbon nanotubes (MWNTs) with a relatively smooth surface and double-walled carbon nanotubes (DWNTs) bundles with a groove structure, were used to induce polyethylene (PE) crystallization for the formation of NHSK. For PE/MWNTs system, NHSK was formed only at a relatively low crystallization temperature (Tc), and PE lamellae are not completely perpendicular to the long axis of MWNTs. However, for PE/DWNTs bundles system, NHSK could be obtained even at a much higher Tc, and almost all the PE lamellae are perpendicular to CNTs long axis, due to the unique "groove structure" formed by DWNTs bundles. The enhanced nucleation ability and the facilitated lamellae orientation by using DWNTs bundles are not only of great crystallography interest but also are very important for functional design in nanodevice applications. [ABSTRACT FROM AUTHOR]

Nanohybrid shish kebab (NHSK) structure, in which fibrous carbon nanotubes (CNTs) act as shish, while polymer lamellae as kebab, is of particular interest both scientifically and technologically. In this work, two types of CNTs with the same diameter range and different topography structure, namely multiwalled carbon nanotubes (MWNTs) with a relatively smooth surface and double-walled carbon nanotubes (DWNTs) bundles with a groove structure, were used to induce polyethylene (PE) crystallization for the formation of NHSK. For PE/MWNTs system, NHSK was formed only at a relatively low crystallization temperature (Tc), and PE lamellae are not completely perpendicular to the long axis of MWNTs. However, for PE/DWNTs bundles system, NHSK could be obtained even at a much higher Tc, and almost all the PE lamellae are perpendicular to CNTs long axis, due to the unique “groove structure” formed by DWNTs bundles. The enhanced nucleation ability and the facilitated lamellae orientation by using DWNTs bundles are not only of great crystallography interest but also are very important for functional design in nanodevice applications. [ABSTRACT FROM PUBLISHER]

This article discusses a study on enhancing the toughness of the recycled polystyrene (rPS) for use as television backset. The study used ethylene-octylene copolymer thermoplastic elastomer (POE) and high-density polyethylene (HDPE) to improve the material's toughness. It exhibited increased impact strength in the rPS/POE binary blends. It also showed a sharp brittle-ductile transition in the recycled polystyrene (rPS) blended with styrene-butadiene-styrene copolymer (SBS).

Elastomeric cellular materials with different ordered microstructures are additively manufactured in this work. Via designing the microscale architectures, the cellular materials can distinguish their mechanical behaviors among uniaxial compressive, bending, and combinative deformations. Theoretical models are developed herein, and both calculation and experiment results note that the mechanical behaviors of the cellular materials highly depend on the filament layer height, the spacing, and the diameter. In comparison with traditional elastomeric cellular, the additively manufactured soft samples can finetune their mechanics to meet the different requests and would be beneficial in extensive applications. [ABSTRACT FROM AUTHOR]

Correction for ‘A robust and flexible bulk superhydrophobic material from silicone rubber/silica gel prepared by thiol–ene photopolymerization’ by Yongsheng Li et al., J. Mater. Chem. A, 2019, DOI: URL10.1039/c8ta11111a/URL. [ABSTRACT FROM AUTHOR]

Poly(chloro-p-xylylene) (PPXC) film has a water contact angle (WCA) of only about 84°. It is necessary to improve its hydrophobicity to prevent liquid water droplets from corroding or electrically shorting metallic circuits of semiconductor devices, sensors, microelectronics, and so on. Herein, we reported a facile approach to improve its surface hydrophobicity by varying surface pattern structures under different temperature and relative humidity (RH) conditions on a thermal curable polydimethylsiloxane (PDMS) and hydrophobic silica (SiO2) nanoparticle coating. Three distinct large-scale surface patterns were obtained mainly depending on the contents of SiO2 nanoparticles. The regularity of patterns was mainly controlled by the temperature and RH conditions. By changing the pattern structures, the surface wettability of PPXC film could be improved and its WCA was increased from 84° to 168°, displaying a superhydrophobic state. Meanwhile, it could be observed that water droplets on PPXC film with superhydrophobicity were transited from a “Wenzel” state to a “Cassie” state. The PPXC film with different surface patterns of 200 μm × 200 μm and the improved surface hydrophobicity showed wide application potentials in self-cleaning, electronic engineering, micro-contact printing, cell biology, and tissue engineering. [ABSTRACT FROM AUTHOR]