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The polyolefin elastomer (POE) was added to polypropylene (PP) to prepare PP composites, and the influence of different POE content on the properties of PP composites was explored. The results show that in terms of the mechanical properties of the material, the tensile strength decreases with the increase of POE content of the thermoplastic elastomer, while the elongation at break, bending strength and impact strength increase first and then decrease with the increase of POE content of the thermoplastic elastomer. Due to the addition of the filler, the composites have good thermal stability and reach the maximum value when the mass fraction of POE is 6%, and the mechanical properties are also optimal. After aging, compared with pure PP materials, PP composites can also maintain their excellent mechanical properties. Therefore, the prepared PP composites can be used in building water supply. [ABSTRACT FROM AUTHOR]

Musculoskeletal modeling is a cost-effective way to design and test wearable robots, ensuring maximum efficiency for individuals. This article explores the simulation of exoskeletons to support the lower limbs and reduce the metabolic cost of walking. The exoskeleton consists of a flexible joint as an actuator made up of four elastomers that store the negative power of the knee joint during the walking cycle as energy, and release it to assist the wearer in the next phase of walking. The Computed Muscle Control (CMC) algorithm in OpenSim is used to find joint torque, total metabolic savings, and the resulting changes in muscle activity. Subsequently, the behavior of implementing the passive exoskeleton is evaluated and the results are compared to a semi-active robot on lower body limbs. The study concluded that while the passive robot exerts extra force on the hamstring muscles in the first half of the swing phase and increases the torque applied to the knee joint. It decreases the activity of the quadriceps muscles in the second half. To compensate for this problem exoskeletons are commonly equipped with a motor. However, this article's findings suggest that utilizing the motorized robot, while decreasing the torque in the targeted joint, actually boosts the performance of surrounding muscles and consumes more metabolic energy than in a passive state. [ABSTRACT FROM AUTHOR]

Absolute anchorage systems like mini-implants, bone screws, and mini-plates have been a landmark evolution in the modern orthodontic world providing an added armamentarium in the hands of orthodontists to treat their patients with utmost efficiency. Unlike other systems, the extra radicular placement and limited surgical exposure make the bone screws such as infrazygomatic crest screws (IZC screws) superior, and to capitalize on these benefits, stability of the implant is vital that relies on their precise placement and angulation. Hence, this article presents a simple implant guide with elastomeric impression material for the precise positioning of IZC screws with utmost ease in fabrication. [ABSTRACT FROM AUTHOR]

When dielectric-elastomer (DE) resonators are operated under large alternating voltage excitations, strong geometric and material nonlinearities can significantly affect the dynamic performance. Based on the virtual work principle, a dynamic model of a circular DE resonator is established in this work. Static analysis is conducted to study the impacts of the control voltage on the strain and natural frequency of the DE resonator at equilibrium. A modified Incremental Harmonic Balance and arc-length methods are used to obtain dynamic responses of the system excited by alternating voltages, and stability analysis is conducted using the Floquet theory. The effects of the mechanical parameters are studied, and period-doubling bifurcations are observed, which are produced by the parametric excitation of the voltage. The bifurcation phenomenon is comprehensively investigated through analysis of the voltage, stress, and damping coefficient, which provides design guidance for DE resonators. [ABSTRACT FROM AUTHOR]

The electrical properties of polymer nanocomposites are governed by the behavior of the internal charges. In particular, the interphase around the nanoparticles strongly influences the distribution and mobility of charge carriers within the nanocomposites, which, in turn, impacts the performance of these materials. In this work, we probe the internal charge behavior in the presence of nanoparticles with a focus on the low-frequency regime using a suite of techniques. By investigating the depolarizing currents and the dependence of the dielectric properties on the frequency and temperature, we demonstrate that the interphases redistribute the space charges, increase their trap depth, and suppress the electrode polarization in an elastomeric nanocomposite. Additionally, we study the effect of the nanoparticle content on the dielectric behavior by comparing the internal charge behavior of 1, 2, and 4 vol. % nanocomposites. At only 4 vol. % loading, the mobility of charge carriers is effectively limited, leading to lower dc conductivity compared to the unfilled elastomer, and 1 and 2 vol. % nanocomposites. These findings are based on the model materials used in this study, TiO2 nanoparticles and polydimethylsiloxane, and can be extended to other nanoparticulate-filled elastomer composites to design lightweight dielectrics, actuators, and sensors with improved capabilities. Judicious manipulation of interfacial phenomena in polymer nanocomposites—especially those with a dilute content of nanoparticles—provides a promising path forward for the design of materials with exceptional electrical and other physical properties. [ABSTRACT FROM AUTHOR]

In this paper, a series of novel trans-1, 4-polyisoprene/isotactic polybutene (TPI/iPB) in-reactor blends were synthesized by isoprene and butene sequential two-stage polymerization technology with spherical Ti[Cl.sub.4]/Mg[Cl.sub.2] type Ziegler-Natta catalyst. The components, structures, and properties of the asobtained TPI/iPB reactor blends were characterized by gel permeation chromatography, Fourier transform Infrared spectroscopy, and differential scanning calorimetry. The active trans-1, 4-polyisoprene (TPI) particles obtained in the initial isoprene polymerization by the Z-N catalyst can be acted as microreactors to initiate butene polymerization subsequently. The TPI/iPB reactor blends with varied components were in situ synthesized within the reactor. The preparative-temperature rising elution fractionation (p-TREF) technique was used to fractionate the TPI/iPB reactor blends based on the elution temperature ranged from -40[degrees]C to 90[degrees]C. The weight distribution and microstructure of each fraction were investigated. The reactor blends are composed of crystallizable high trans-1, 4-uint polyisoprene obtained from the first-stage isoprene polymerization, high isotactic polybutene obtained from the secondstage butene polymerization and TPI-b-iPB block copolymer with different sequence structure obtained from the initial time of the second stage. This work is expected to propose the possible polymerizations of a-olefins and conjugated dienes by using heterogeneous Ziegler-Natta catalyst and provide a kind of novel rubber/plastic reactor blend materials. Highlights * The first synthesis of the trans-1,4-polyisoprene/isotactic polybutene reactor blends. * p-TREF technique was used to analyze the composition of TPI/iPB reactor blends. * Detailed structure characterization of the fractions including GPC and NMR * TPI-b-iPB block copolymer can be obtained through the sequential polymerization. * Rubber/plastic reactor blend materials were fabricated by the Z-N catalyst. KEYWORDS 4-polyisoprene, in-reactor blends, polybutene, temperature rising elution fractionation, trans-1, Ziegler-Natta catalyst, 1 | INTRODUCTION The discovery of Ziegler-Natta catalysts has been one of the greatest developments in the synthesis of stereospecific polymers in both academy and modern industry. (1-4) The first [...]

Polymeric materials have long been at the forefront of materials science due to their exceptional physical and chemical properties. Designing new polymeric materials traditionally relies on a combination of physical and chemical principles along with empirical trial and error methods. A big issue in this approach is that the traditional trial and error experiments/simulations are often time consuming and sometimes inefficient in order to achieve targeted properties. Machine learning (ML) offers a promising solution to this issue. By leveraging ML algorithms, researchers can accelerate the design process, predict material properties more rapidly, and optimize formulations. ML approaches can analyze vast amounts of data, uncover hidden patterns, and generate predictive models that significantly reduce the time needed to develop materials with desired properties. This paradigm shift allows for more efficient exploration of the material space and faster innovation in polymeric material design. The current review article focuses on the application of ML methods to help design polymeric materials, more especifically, thermosets, thermoplastics and elastomers. Additionally, the review explores future possibilities and opportunities arising from the state-of-the-art advancements in ML, offering perspectives on how these technologies might evolve and influence the polymer science domain.

The development of rigid yet fatigue‐resistant elastomers possess a critical challenge, necessitating materials capable of enduring substantial mechanical loads while maintaining structural integrity through cycles of deformations. Despite soft materials achieving a fatigue threshold of ∼1000 J m−2, their modulus, typically ∼1 MPa, restricts their applications. This study presents a breakthrough in designing rigid, fatigue‐resistant elastomers by controlling nanosheet orientation within the network using a shear force strategy. The elastomers achieve a high fatigue threshold of 1900 J m−2 while maintaining a high elastic modulus of 8 MPa. These superior mechanical properties are attributed to the synergistic effects of microscale alignment of nanosheets and robust interfacial bonding between the polymer chains and nanosheets at the nanoscale. When the nanosheet volume fraction is below the percolation threshold, well‐dispersed nanosheets transfer load effectively through strong interfacial bonding with the polymer, significantly suppressing fatigue crack propagation. Conversely, above the percolation threshold, agglomerated nanosheets create defects in the matrix, reducing load‐bearing capacity. The innovative elastomers demonstrate potential for a wide range of applications, including automotive components, actuators, and stretchable electronic devices, where high mechanical stability and load‐bearing capacity are essential. [ABSTRACT FROM AUTHOR]

The exploitation of bio‐based materials derived from renewable resources represents a pivotal strategic approach in addressing environmental pollution and alleviating the scarcity of fossil resources. 2,5‐Furandicarboxylic acid (FDCA) is the most potential substitute for terephthalic acid. Lignin is the most abundant aromatic biomass resource. However, the preparation of high‐performance lignin/FDCA‐based bio‐polyesters remains a formidable challenge. Herein, a multifunctional lignin‐modified polyester elastomer (LFPEe) is designed using FDCA‐based polyester oligomer (PPeF) and lignin (AOH) as building blocks. The LFPEe exhibits superior mechanical properties with the optimum tensile strength, fracture strain, and elastic recovery ratio up to 58.9 MPa, 610% and 88.9%, respectively, attributing to the formation of dual cross‐linking network with nanophase separation structure. Furthermore, leveraging the inherent characteristics of lignin, the LFPEe demonstrates excellent light‐controlled shape memory and excellent UV shielding performance. This innovative work not only breaks the performance dependence of FDCA‐based polyester on high molecular weight but also highlights a novel paradigm for value‐added utilization of lignin in sustainable bio‐polyesters. [ABSTRACT FROM AUTHOR]

In the rapidly evolving field of human-machine interfaces (HMIs), high-resolution wearable electronic skin (e-skin) is essential for user interaction. However, traditional array-structured tactile interfaces require increased number of interconnects, while soft material-based computational methods have limited functionalities. Here, we introduce a thin and soft e-skin for tactile interfaces, offering high mapping capabilities through electrical impedance tomography (EIT). We employed an organic/inorganic hybrid structure with simple, cost-effective fabrication processes, ensuring flexibility and stability. The conductive and stretchable sensing domain includes a micropatterned multiwall carbon nanotube and elastomer composite. The skin-like tactile interface effectively detects pressure-induced conductivity changes, offering superior spatiotemporal resolution with fewer interconnects (pixel/interconnects >57). This EIT-based tactile interface discerns external pressures to a submillimeter degree and vertical deformations of a few hundred micrometers. It sustains stable functions under external damage or environmental changes, confirming its suitability for persistent wearable use. We demonstrate practical applications in real-time HMIs: handwriting recognition and drone control. [ABSTRACT FROM AUTHOR]

Flexible and stretchable ion‐conductive elastomers have shown promising applications in wearable flexible sensor devices, biopotential detection, electroluminescent devices, and other areas. However, the currently employed gel‐based ion‐conductive materials encounter issues such as solvent volatilization or leakage. Herein, there is an urgent requirement to develop a solid‐state ionic conductor material that is both safe and reliable, free from issues of liquid leakage. Here, the study reports a solid‐state ion‐conductive elastomer with excellent mechanical properties and high ionic conductivity based on a synergistic strategy of multiple interaction forces. The solid‐state ion−conductive elastomer exhibits high ionic conductivity (1.42 × 10−4 S cm−1 at 25 °C), superior stretchability (≈1550% elongation) and strength (1.48 MPa). Moreover, the solid‐state ion‐conductive elastomer exhibits high resilience and possesses excellent self‐healing ability. The wearable sensor, prepared based on the solid‐state ion‐conductive elastomer with excellent comprehensive performance, not only demonstrates high strain sensitivity but also captures high‐quality epidermal biopotential signals from the human body in biopotential detection. Additionally, the solid‐state ion‐conductive elastomer can serve as an electrode in ionic electroluminescent devices for human wearable applications. It is believed that the solid‐state ion‐conductive elastomer can provide novel opportunities for the advancement of wearable devices and soft ionotronics. [ABSTRACT FROM AUTHOR]

Wearable sensors for high temperatures (WSHT) applications pose a significant challenge in the electronics field due to the inherent inability of most electronics to function in harsh environments. Triboelectric nanogenerators (TENG) present a substantial potential for applications in such challenging conditions. Herein, a fully‐recyclable flame‐retardant triboelectric elastomer is developed, which exhibits superior charge stability under high temperature conditions and proposes the specially designed synergistic fillers that play a dual role by trapping more charges into the interface and stabilizing the char layers via layer‐ball‐layer structure. An efficient flame‐retardant system is presented, which exhibits a 31% lower fire growth index than the individual components. The maximum surface charge density of this triboelectric elastomer can reach 361 µC m−2, while this surface charge density can be preserved to 70.9% after 16 s of combustion (≈520 °C) and to 37.9% by continuously working at 130 °C. At last, utilizing this flame‐retardant triboelectric elastomer, smart firemen's boots featuring gait analysis for identification and second level early warning systems have been developed. This work paves the way for the development of triboelectric materials and intelligent wearable devices suitable for applications in harsh environments. [ABSTRACT FROM AUTHOR]

Stretchable organic photovoltaics (OPVs) are pivotal for advancing conformable electronics, yet achieving both efficient and intrinsically stretchable OPVs remains a significant challenge. The main issue is maintaining electronic and mechanical properties under deformation. Here, a ternary blend system, PTzBI‐oF:PYIT:EVA is presented, incorporating ethylene‐vinyl acetate (EVA) to establish a conjugated and elastomeric dual‐network morphology. The elastomer network dissipates applied stress, preserving the crystalline packing of the conjugated network and enabling improved mechanical stability of charge carrier generation and transport. Specifically, with 15% EVA content, the ternary blend achieved a power conversion efficiency (PCE) of 15.28% in rigid devices and exhibited a crack onset strain of 17.23%. Notably, the stretchable OPVs retained over 80% of their initial PCE under 30% strain. These findings underscore the potential of conjugated and elastomeric dual‐network morphology in developing high‐performance stretchable electronics for various applications. [ABSTRACT FROM AUTHOR]

Liquid metal or liquid metal microparticles (LMP) based conductive inks, though promising for fabrication of circuits for use in soft and stretchable electronics, are constrained by a few drawbacks such as need for encapsulation, need for sintering to induce conductivity, and smearing. To address these issues, herein, a stretchable conductive composite ink is developed by combining LMPs with carbon black (CB) in highly entangled polysiloxane elastomer. LMP‐dispersed elastomer lacks conductivity because of its non‐percolated network, however, the CB can interconnect LMPs to act as a bridge, thereby imparting conductivity to the elastomer. Due to presence of fluidic LMPs, the LMPs‐dispersed elastomer lies in soft regime with initial conductivity of 5.6 S m−1, aided by the presence of CB in the interstitial spaces between the LMPs. The highly entangled molecular network of the encapsulating elastomer endows the resulting composite with high stretchability (≈286%) and softness (0.648 MPa) and its long pot life enables rheological modulation of the ink to achieve pressure‐driven direct printed non‐smearing traces. The LMPs‐based conductive ink developed in this work is expected to be further utilized in the fabrication of soft robotics and electronic skin and integrated into electronic modules by facile direct 3D printing. [ABSTRACT FROM AUTHOR]

It remains enormous challenges to balance the conflict between high strength and toughness mechanical properties and excellent room‐temperature self‐healing abilities of polyurethane elastomers. In this work, we report a recyclable room‐temperature self‐healing polyurethane elastomer with excellent mechanical properties. The prepared polyurethane elastomer (PU‐DA‐Zn0.50) exhibits high tensile strength of 15.33 MPa, high toughness of 76.77 MJ m−3, and high elongation at break of 1604.46% by introducing isophorone diamine (IPDA), 1‐(3‐aminopropyl) imidazole (IMZ) and zinc ions into polymer system to form a dynamic double‐cross‐linked structure (hydrogen bonds and Zn2+‐imidazole coordination bonds). In addition, the tensile strength of fractured polyurethane can reach more than 80% of the original sample after 48 h of self‐healing at room temperature without external stimuli, which is attributed to the kinetics of rapid exchange of Zn2+‐imidazole coordination bonds at room temperature. It is worth noting that the balance between excellent mechanical properties and outstanding room‐temperature self‐healing ability can be optimized by adjusting the Zn2+‐imidazole coordination bond density in the system. Moreover, the dynamic nature of the double‐cross‐linking network endows polyurethane with favorable recyclability. The above remarkable comprehensive performances reveal a great potential of PU‐DA‐Znx elastomer in the fields of wearable flexible electronic devices such as bionic skin, human motion monitoring, and soft robots. [ABSTRACT FROM AUTHOR]

Theoretically, separating the positive and negative charge centers of the chain segments of dielectric elastomers (DEs) is a viable alternative to the conventional decoration of chain backbone with polar handles, since it can dramatically increase the dipole vector and hence the dielectric constant (ε′) of the DEs while circumvent the undesired impact of the decorated polar handles on the dielectric loss (tan δ). Herein, a novel and universal method is demonstrated to achieve effective separation of the charge centers of chain segments in homogeneous DEs by steric hindrance engineering, i.e., by incorporating a series of different included angle‐containing building blocks into the networks. Both experimental and simulation results have shown that the introduction of these building blocks can create a spatially fixed included angle between two adjacent chain segments, thus separating the charge center of the associated region. Accordingly, incorporating a minimal amount of these building blocks (≈5 mol%) can lead to a considerably sharp increase (≈50%) in the ε′ of the DEs while maintaining an extremely low tan δ (≈0.006@1 kHz), indicating that this methodology can substantially optimize the dielectric performance of DEs based on a completely different mechanism from the established methods. [ABSTRACT FROM AUTHOR]

Dielectric elastomer actuators (DEAs) are emerging as promising candidates for various applications in robotics and optical devices due to their lightweight, miniaturization potential, high energy density, simple structure, and low power consumption. However, their effective actuation always demands sophisticated high-voltage driving circuits that are compact and responsive. DEAs need to be capable of generating intricate high-voltage waveforms or simultaneously controlling multiple quadrants with distinct high-voltage levels. This paper proposes a high-voltage power supply for DEAs, featuring a four-quadrant high-voltage driving circuit. The circuit is capable of independently generating high-voltage signals ranging from 100 V to 6000 V and producing arbitrary waveforms with adjustable frequencies. The independent operation of the quadrants without crosstalk showcases the system's integration and potential for cross-disciplinary applications. [ABSTRACT FROM AUTHOR]

In this paper, anisotropic magnetorheological (MR) elastomers have been prepared using a magneto-thermal coupling process. The composition of these elastomers includes a silicone rubber matrix, carbonyl iron particles (CIP), and assorted additives. We have conducted experimental and modeling studies to analyze the dynamic mechanical properties of MREs under varying conditions of temperatures, magnetic field strengths, displacement amplitudes, and frequencies. Furthermore, to explore the variations in shear storage modulus and loss factor under diverse loading conditions, two MRE vibration mitigation devices with varying CIP weight fractions have been prepared and tested in shear mode. The findings indicate that the MRE devices exhibit pronounced temperature-dependent and magnetorheological effects. Notably, both the shear storage modulus and loss factor increase with rising magnetic field strength, excitation frequency, and CIP weight fraction, whereas they decrease as ambient temperature and displacement amplitude rise. Building on these results, a modified fractional order derivative microstructure (MFMS) model which integrates the molecular chain network of MREs with the temperature–frequency equivalence principle has been proposed to predict and characterize the dynamic viscoelastic properties of MREs under various working conditions. A comparative analysis of experimental and model-calculated data confirms that the proposed model accurately describes the dynamic viscoelastic properties of MREs. [ABSTRACT FROM AUTHOR]

Poly(eutectic) elastomers, as an emerging category of flexible electronic materials, have garnered growing interest for their cost-effectiveness, non-volatility, and biocompatibility. Nonetheless, they encounter challenges including limited functionalities, sensitivity, durability, and mechanical properties. This study involved synthesizing various MXene-doped poly(eutectic) elastomers using robust acrylamide and soft acrylic acid as organic monomers, minor MXene nanosheets as inorganic fillers and physical crosslinkers, and a rapid in-situ photopolymerization method within 2 min. Owing to the synergistic effect of thermodynamic self-assembly, high-density hydrogen bonding, and cation-dipole interactions in the matrix networks, the resulting non-covalently crosslinked elastomers exhibited remarkable mechanical strength (up to ∼ 16.2 MPa) and impressive tensile properties (nearly 700 %), along with rapid electrical self-healing (within 0.046 s) and the ability to withstand loads up to 2500 times their weight following self-healing without fracturing. Notably, these elastomers also demonstrated excellent microstrain (1 %–10 %) sensitivity with a gauge factor of 2.02, wide temperature tolerance (−20 °C ∼ 60 °C), outstanding harsh temperature durability (−20 °C) exceeding 22,000 cycles, and antibacterial properties. Furthermore, these elastomers-assembled strain sensors displayed real-time and rapid response in human motion detection and wireless signal transmission, presenting a promising approach for designing functionally integrated elastomeric materials. [Display omitted] • A novel MXene-doped poly(eutectic) conductive elastomers are facilely fabricated. • Tunable mechanical properties by adjusting ratios of soft monomer, hard monomer and physical crosslinker. • Dynamic non-covalent interactions confer rapid electrical self-healing (<46 m s). • Over 22,000 cycles durability in harsh temperatures (−20 °C). • Real-time response to strain, human motion and wireless signal transmission. [ABSTRACT FROM AUTHOR]

The implementation of hot melt adhesives reaching structural adhesion with both impact resistance and detachability is of prospective industry value but still remains challenging. In this work, 2‐amino‐4‐hydroxy‐6‐methylpyrimidine serving as both chain extender and end‐capping reagent due to its isomerism, was developed to construct a supramolecular polyurethane‐derived hot melt structural adhesive. The as‐synthesized PUM elastomers occurs obvious decrease of molecular weight at 80°C compared to room temperature, revealing the existence of self‐complementary 2‐ureido‐4[1H]‐pyrimidinone (UPy) motifs at chain ends. This unique structure allows to chemically incorporate abundant hierarchical and quadruple hydrogen bonding moieties, which results in remarkable enhancement of shear strength, ranging from 6.4 to 16.6 MPa. More importantly, it also exhibits unique impact‐strengthening and reproducible adhering ability. The Hopkinson‐press‐bar and cyclic tensile tests manifest that quadruple hydrogen bonds play a pivotal role in buffering external forces and increasing energy dissipation when exposed to high velocity impacts. The true stress and strain synchronously increase as the strain rate augments while the shear strength can even roar up to ~18 MPa at high tensile speed. With regard to mild synthetic conditions, atomic economic use of reactants, it is promising that this material has industrial potential to be utilized in applications referred to energy‐absorption and reproducible structural adhesion. [ABSTRACT FROM AUTHOR]

Mechanism models based on chain-like structures are often used to characterize the morphology of magneto-rheological elastomer (MRE) and provide theoretical guidance for MRE preparation. However, widely used shear and tension mechanism models based on oblique straight chain or bent-chain structures have the limitation of insufficient accuracy in characterization, mainly because the internal particle chains of anisotropic MRE are not simple oblique straight or bent from scanning electron microscope (SEM) results. Therefore, the particle chain formation and particle interaction mechanism within MRE are revealed firstly. The theoretical results shows that particles tend to form S-like chain structures due to complex attraction and extrusion. On this basis, a novel "S" chain mechanism model is proposed, which is confirmed to have higher accuracy than the ideal shear model and tension model by comparing with the experimental results. The main reason is that the "S" chain mechanism model has realized the unification of shear, compressive, or tension mode, and integrates the fully coupled magnetic field, distribution parameters and interface stretching. The "S" chain mechanism model also takes into account the radius and volume fraction of the particles in MRE preparation, which makes it a more accurate guide to subsequent preparation. [ABSTRACT FROM AUTHOR]

Stretchable organic light-emitting diodes (SOLEDs) have been the challenging class of OLEDs as they have limited processability to fabricate a design that can withstand external deformation. Herein, we demonstrated the highly efficient top-emitting geometrical stretchable OLED (GSOLED) by incorporating the prestretched elastomer with optical adhesive film. The experimental and theoretical characterizations verified the enhancement of device efficiencies with the light extraction phenomenon brought by nanowavy corrugated structures. Furthermore, GSOLED shows stability in stretchable conditions and displays narrower emission spectrum with improved color purity. The full width at half maximum (FWHM) of 21 nm shows narrowband emission with a high current efficiency and EQE of 221 cd A−1 and 39.50%. This work marks a significant step forward, providing unprecedented insights into the factors influencing device performance in current and future material systems for stretchable organic light-emitting diodes. [ABSTRACT FROM AUTHOR]

Understanding how dangling fragments of polyurethanes (PU) affect its microphase separation structure and damping properties can provide insights for designing desired materials at the molecular scale. By varying the types of diol extenders (such as 1,2‐ethyleneglycol, 1,2‐propanediol, and 1,2‐butanediol), PU samples with different dangling residues were successfully synthesized. Using atomic force microscopy and small‐angle x‐ray scattering, we confirmed that the introduction of dangling chains disrupts microphase separation and demonstrated a correlation between the degree of suppressed microphase separation and the size of the dangling residues. Fourier transform infrared spectroscopy and molecular dynamics simulations confirmed that dangling chains reduce the hydrogen bonding index while increasing the phase compatibility between soft and hard segments. Differential scanning calorimetry (DSC) measurements revealed an increased glass transition temperature (Tg), indicating hindered movement of backbone segments due to dangling chains. Moreover, lengthening the dangling chains further decreased Tg. Dynamic mechanical analysis (DMA) demonstrated improved damping properties with the introduction of dangling chains, although increasing chain length led to deteriorating damping properties, consistent with observations from DSC. These findings suggest that the variations in macroscopic properties of PU induced by dangling chains are linked to hydrogen bonding interactions and micromorphology at the molecular level. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) cellular assemblies, such as cancer spheroids and organoids, are increasingly valued for their physiological relevance, and versatility in biological applications. Nanopatterns that mimic the extracellular matrix provide crucial topological cues, creating a physiologically relevant cellular environment and guiding cellular behaviors. However, the high cost and complex, time-consuming nature of the nanofabrication process have limited the widespread adoption of nanopatterns in diverse biological applications. In this study, we present a straightforward and cost-effective elastomer replica molding method utilizing commercially available optical discs to generate various nanopatterns, such as nanogroove/ridge, nanoposts, and nanopits, varying in spacing and heights. Using the nanopatterned well chips (NW-Chips), we demonstrated the efficient formation of 3D multicellular self-assemblies of three different types of cancer cells. Our findings highlight the accessibility and affordability of optical discs as tools for nanopattern generation, offering promising avenues for modulating cell behaviors and advancing diverse biological applications. [ABSTRACT FROM AUTHOR]

An analysis and modeling of the linear viscoelastic behavior of maltenes (M) blended with styrene–butadiene–styrene block copolymer (SBS) are presented in this study. M were mixed with different amounts of SBS (Elastomer, E) (0.25–80 wt%) to investigate the effect of polymer concentration on linear viscoelastic response of the blends; storage and loss moduli were obtained from small amplitude oscillatory shear tests (SAOS). Time–temperature superposition master curves were analyzed by a Maxwell multi-modal model with up to nine relaxation times. Han, Cole–Cole and Van Gurp-Palmen diagrams were prepared from the rheological data. Two different responses were observed: At low E contents, a dispersed system rheological response was observed and verified by microscopy with elastomer as the dispersed phase and maltenes as the matrix, while at high E content the response was that of a co-continuous system. Mixtures with E > 2 wt% exhibited change in their thermomechanical properties with a phase inversion at E > 50 wt%. Furthermore, at low E concentration resins stabilize the dispersed phase by diminishing the magnitude of the viscoelastic moduli, conversely, at high E concentration a swelled polymer-rich phase creates a network that significantly influences of the viscoelastic properties. [ABSTRACT FROM AUTHOR]

For probing the structure–property relationships of the polyurea elastomers, we synthesize the siloxane polyurea copolymer elastomer by using two aminopropyl-terminated polysiloxane monomers with low and high number-average molecular weight (Mn), i.e., L-30D and H-130D. To study the influence of the copolymer structures on the film properties, these films are analyzed to obtain the tensile performance, UV-vis spectra, cross-sectional topographies, and glass transition temperature (Tg). The two synthetic thermoplastic elastomer films are characterized by transparency, ductility, and the Tg of the hard domains, depending on the reacting compositions. Furthermore, the film elasticity behavior is studied by the strain recovery and cyclic tensile test, and then, the linear fitting of the tensile data is used to describe the film elasticity based on the Mooney–Rivlin model. Moreover, the temperature-dependent infrared (IR) spectra during heating and cooling are conducted to study the strength and recovery rate of the hydrogen bonding, respectively, and their influence on the film performance is further analyzed; the calculated Mn of the hard segment chains is correlated to the macroscopic recovery rate of the hydrogen bonding. These results can add deep insight to the structure–property relationships of the siloxane polyurea copolymer. [ABSTRACT FROM AUTHOR]

Cholesteric liquid crystal elastomers (CLCEs) has garnered significant attention in the field of information display and storage. Obtaining multiple structural colours in a single elastomer film is highly desirable but presents a considerable challenge. Here, we have successfully achieved manipulable range of structural colours in a CLCE film by ingeniously introducing the photopolymerisation during thiol-acrylate reaction process. This particular strategy involves triggering spatial shrinkage of the polymer network in a pre-designed region following solvent evaporation, resulting in a blue shift of the structural colour compared to the background. Consequently, we can construct multi-colour and multi-pattern elastomer films by precisely controlling the localised polymerisation. Notably, these patterns can be concealed in a reversible manner as the film undergoes a specific degree of elongation and can be restored when external force is removed. This work demonstrates a straightforward method of programming structural-colour modulation range, eliminating the need for material changes or intricate preparation processes, broadening the applications of stretchable elastomers in information storage, encryption, anti-counterfeiting, and dynamic photonics. [ABSTRACT FROM AUTHOR]

For blending immiscible polymers, such as in the toughening modification of polylactide (PLA) via blending with rubbery materials, interfacial compatibilization is of great significance while the mechanism, especially the role of interfacial rheology, remains elusive. In this study, styrene-butadiene block copolymer elastomer (SBC) was employed to toughen PLA and a dumbbell-shaped Janus nanoparticle (JNP) consisting of polymethyl methacrylate and polystyrene spheres with equal size (∼80 nm) was used as the compatibilizer. Located at the interface, JNPs exhibited a great compatibilization efficiency in PLA/SBC blends, as demonstrated by the good morphology stabilization against droplet coalescence under static annealing and low shear flow conditions, as well as by the resistance against droplet breakup under high shear flow conditions. Moreover, as revealed from the linear viscoelasticity of JNP compatibilized blends, when JNP loading is more than 2 phr, aside from shape relaxation, an interfacial relaxation dominated by Marangoni stress was observed, indicating the possibility of particle redistribution on droplet surfaces. However, when loading is more than 4 phr, relaxations in the terminal zone no longer exist, implying the possible formation of a particle network on the droplet surface. This is consistent with the mechanical properties. The blend shows the greatest toughness at JNP loading around 3 phr, while the toughness is very poor when JNP loading is either too low or too high. This suggests interfacial relaxation to be crucial to guarantee a good toughening effect of SBC in PLA. [ABSTRACT FROM AUTHOR]

Styrene-Isobutylene-Styrene (SIBS) is a high-performance biocompatible elastomeric material. However, its low surface energy and hydrophobic nature limit its widespread application in the field of implantable materials within the human body. In this study, UV-initiated polymerization was employed to prepare SIBS-acrylic acid surface-grafted co-polymer. Subsequently, collagen protein (Coll) surface modification of SIBS was achieved through a coupling reaction with acrylic acid, resulting in the production of Collagen Surface-Modified SIBS, denoted as SIBS-AA-Coll. Characterization was carried out using techniques such as infrared spectroscopy, thermal analysis, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS), and water contact angle measurements. The results demonstrated that, with a UV exposure time of 4 min and a nBP:nAA ratio of 15:100, the grafting ratio reached 9.4%, significantly improving the hydrophilicity of the SIBS surface. In vitro cytotoxicity tests and in vivo animal implantation experiments indicated that Collagen Surface-Modified SIBS exhibited excellent biocompatibility. [ABSTRACT FROM AUTHOR]

Carbon nanotubes (CNTs) are often regarded as semi-rigid, all-carbon polymers. However, unlike conventional polymers that can form 3D networks such as hydrogels or elastomers through crosslinking in solution, CNTs have long been considered non-crosslinkable under mild conditions. This perception changed with our recent discovery of UV-defluorination-driven direct crosslinking of CNTs in solution. In this study, we further investigate the thermal stability of UV-defluorination-driven crosslinked CNTs, revealing that they are metastable and decompose more readily than either pristine or fluorinated CNTs under Raman laser irradiation. Using Raman spectroscopy under controlled laser power, we examined both single-walled and multi-walled fluorinated CNTs. The results demonstrate that UV-defluorinated CNTs exhibit reduced thermal stability compared to their pristine or untreated fluorinated counterparts. This instability is attributed to the strain on the intertube crosslinking bonds resulting from the curved carbon lattice of the linked CNTs. The metallic CNTs in the crosslinked CNT networks decompose and revert to their pristine state more readily than the semiconducting ones. The inherent instability of crosslinked CNTs leads to combustion at temperatures approximately 100 °C lower than those required for non-crosslinked fluorinated CNTs. This property positions crosslinked CNTs as promising candidates for applications where mechanically robust, lightweight materials are needed, along with feasible post-use removal options. [ABSTRACT FROM AUTHOR]

A new anisotropic visco-hyperelastic constitutive model has been developed to predict the time-dependent deformation response of flexible, knitted fabric-reinforced elastomer composites. These composites exhibit a time-dependent response due to the viscoelastic behavior of the elastomer, while the anisotropic reinforcement effect is attributed to the knitted fabrics. The proposed modeling approach features an invariant-based strain energy density function that incorporates the architecture of knitted fabrics and the hyper-viscoelastic behavior of elastomers. In this study, the elastomer is considered as a viscous neo-Hookean material, and the knitted fabrics are modeled as cords with negligible stiffness in bending. The proposed material model is implemented in commercial Finite Element Analysis (FEA) software, Abaqus (version 2017), through a user-defined material subroutine, UMAT. This approach enables the determination of the constitutive behavior of the composite based on the constituent elastomer, fiber properties, and fabric architectures. The proposed model is verified through a discrete 3D FEA model, in which the elastomer and fabric reinforcement are modeled explicitly. The approach is further validated through physical testing including uniaxial tension, torsion, and three-point bending. Since the proposed strain energy-based constitutive model can predict the deformation response of knitted fabric-reinforced elastomer composites based on the fabric architecture, it can be employed as an efficient modeling tool to aid the design of knitting pattern for target mechanical properties. [ABSTRACT FROM AUTHOR]

In this research, twisting behavior of a multi-layered hydrogel-based actuator which is comprised of two temperature-sensitive hydrogel layers and one elastomeric layer as the main core, is studied in different aspects due to the temperature changes. For this purpose, firstly, a suitable model for temperature-sensitive hydrogel is implemented in ABAQUS software by using UHYPER subroutine. Then, twisting behavior of the actuator is simulated due to temperature changes and both twisting angle and reaction torque are obtained for the actuators with different boundary conditions. To study the effect of different material and geometric parameters on the performance of under-study actuator, a comprehensive parameter study is conducted. These parameters include cross-linking density of the hydrogel, volumetric percentage of the hydrogel, geometry of interface line of the layers, and aspect ratio (cross-section dimensions) of the actuator. Considering the obtained results, the actuators with the maximum twisting angle and maximum reaction torque are recognized. Briefly, the reaction torque generated at the ends of the twisting actuator is maximum for the case where the interface line passes through the corners of the actuator cross-section. But the results show that for the maximum twisting angle of the under-study actuator, the so-called interface line should not pass through the actuator corners. [ABSTRACT FROM AUTHOR]

Polymeric elastomers are widely utilized in implantable biomedical devices. Nevertheless, the implantation of these elastomers can provoke a robust foreign body response (FBR), leading to the rejection of foreign implants and consequently reducing their effectiveness in vivo. Building effective anti-FBR coatings on those implants remains challenging. Herein, we introduce a coating-free elastomer with superior immunocompatibility. A super-hydrophilic anti-fouling zwitterionic layer can be generated in situ on the surface of the elastomer through a simple chemical trigger. This elastomer can repel the adsorption of proteins, as well as the adhesion of cells, platelets, and diverse microbes. The elastomer elicited negligible inflammatory responses after subcutaneous implantation in rodents for 2 weeks. No apparent fibrotic capsule formation was observed surrounding the elastomer after 6 months in rodents. Continuous subcutaneous insulin infusion (CSII) catheters constructed from the elastomer demonstrated prolonged longevity and performance compared to commercial catheters, indicating its great potential for enhancing and extending the performance of various implantable biomedical devices by effectively attenuating local immune responses. The foreign body response remains a significant challenge for implants. Complicated coating procedures are usually needed to construct anti-fibrotic coatings on implantable elastomers. Herein, a coating-free elastomer with superior immunocompatibility was achieved using a zwitterionic monomer derivative. A pure zwitterionic layer can be generated on the elastomer surface through a simple chemical trigger. This elastomer significantly reduces protein adsorption, cell and bacterial adhesion, and platelet activation, leading to minimal fibrotic capsule formation even after six months of subcutaneous implantation in rodents. CSII catheters constructed from the PQCBE-H elastomer demonstrated prolonged longevity and performance compared to commercial catheters, highlighting the significant potential of PQCBE-H elastomers for enhancing and extending the performance of various implantable biomedical devices. [Display omitted] [ABSTRACT FROM AUTHOR]

Polymeric elastomers are extensively employed to fabricate implantable medical devices. However, implantation of the elastomers can induce a strong immune rejection known as the foreign body response (FBR), diminishing their efficacy. Herein, we present a group of immunocompatible elastomers, termed easy-to-synthesize vinyl-based anti-FBR dense elastomers (EVADE). EVADE materials effectively suppress the inflammation and capsule formation in subcutaneous models of rodents and non-human primates for at least one year and two months, respectively. Implantation of EVADE materials significantly reduces the expression of inflammation-related proteins S100A8/A9 in adjacent tissues compared to polydimethylsiloxane. We also show that inhibition or knockout of S100A8/A9 leads to substantial attenuation of fibrosis in mice, suggesting a target for fibrosis inhibition. Continuous subcutaneous insulin infusion (CSII) catheters constructed from EVADE elastomers demonstrate significantly improved longevity and performance compared to commercial catheters. The EVADE materials reported here may enhance and extend function in various medical devices by resisting the local immune responses. Fibrous capsule formation limits the lifetime of implanted devices. Here, the authors report on an elastomer designed to reduce the immune response which shows enhanced device utility in both mice and non-human primate models, including in an insulin infusion catheter model. [ABSTRACT FROM AUTHOR]

Attention has recently been given to finding alternative and sustainable raw material sources for wood and metal adhesives, such as polyvinyl alcohol (PVA), corn starch (CS), arabic gum (AG), and dextrins (D). Modifying polymer dispersion using unique substances, such as modifying reactive elastomer liquid (EL) using PVA, CS, AG, or D results in sufficiently moisture-resistant adhesive joins. In the present study, the physical characteristics of EL/blended with the natural polymers PVA, CS, AG, and D, based on high-density fiberboard (HDF) wood and aluminum (Al) adhesives and coatings, were investigated and compared to those of pure EL. The EL was blended with PVA, CS, AG, or D at a ratio of 60/40 (w/w) to form EL/blends. The chemical structures, surface and interface morphology, adhesion strengths (including shear strength and pull-off strength), surface roughness, wettings, color intensity, and thermal insulation of the prepared EL and EL/blends were investigated. A scanning electron microscopy (SEM) investigation confirmed filler dispersion and adhesion between the blends, and coated HDF wood, or Al. The developed EL/AG blend had a pull-off strength of 144±5 and 102±3 MPa and a shear strength of 771±11, and 52±3 N with HDF wood and Al substrate, respectively. The EL/PVA blend had a maximum surface roughness value 4.57 μm, and its average water contact angle (WCA) was 85.6°. A plasma jet was used to treat the surface roughness and hence the wettability of the pure EL and the EL/blends, for example, plasma treatment decreased the roughness of the EL/AG blend from 4.36 to 3.28 μm. WCA, and hence wettability, was also significantly influenced by plasma treatment, for example, plasma treatment decreased the WCA of the pure EL from 71.7±0.4° to 30.7±0.7°. The lightness value of the EL/blends was less than that of the pure EL, indicating that (the color adhesives have darkened). Similarly, the yellowness-blueness and redness-greenness values of the EL/blends were greater than those of the pure EL, (rendering the blended adhesives more reddish and bluish). The EL/AG blend was found to have a minimum thermal conductivity (of 0.27 W/m.K), indicating maximum insulation. [ABSTRACT FROM AUTHOR]

The paper presents a parallel between the calculation of deformations for uniaxially compressed rubber spheres, by direct measurement on the experimental stand. Generalities about rubber, definition, properties, main characteristics and examples of use, are presented. The authors' original experimental study is then presented to study the deformability of rubber spherical bodies and to analyze the deviations of rubber behavior from Hertzian model. An experimental rig was designed for this purpose. Its operation and the working method used, as well as the force-strain characteristics for different experimental situations (spheres'arrangement and support) are presented, that being the compression of two or three rubber spheres, with three different ways of supporting them. Considering that a model that accurately describes the behavior of rubber the spheres are made of is the Money-Rivlin model, which is characterized by two constants, C10 and C01, these constants were determined by a simple method, using the hardness of the material as a basic element hyperelastic, measured on the Shore A scale. After determining the material constants, the deformation values were also determined by numerical modeling with the help of Ansys software. For validation, the experimental curve for the deformation of a rubber sphere on a plane and the numerical curve for the similar situation with the experimentally determined mechanical characteristics, were plotted on the same graph. Finally, the conclusions resulting from the conducted research are presented: - highlighting two ways of evaluating the deformation of rubber spheres, experimentally and numerically, determining the specific Mooney-Rivlin constants of the material through a simple, efficient and valid method, - a way to calculate deformations for this case of loading rubber spheres is to model them as an axisymmetric contact (reducing the model to a quarter), - by finite element method, because it uses a lower number of finite elements and saves significant resources, both the calculation method and the experimental methods used are validated by a good correspondence between the experimental curve and numerical results. [ABSTRACT FROM AUTHOR]

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Novel elastomers are made by reaction of hydroxyl‐terminated polyacrylic ester (HyTemp) with polyethylene glycol (PEG, number of ethylene glycol units 1, 3, 6, 9) based cross‐linkers. The influence of the cross‐linker length, the HyTemp/cross‐linker (w/w) ratio and the cross‐linking accelerator trifluoromethanesulfonate scandium salt (ScTFMS) on the structure and the properties of the materials are studied. The cross‐linker length has not influence on the glass transition (Tg) of the products because of the presence of the flexible PEG units that cancels out the cross‐linking effect associated to a shift to higher Tg. A two‐domain structure is seen by the presence of a dual Tg in samples cured with ScTFMS. Mathematical analysis of the modulated differential scanning calorimetry curves offers for the first time the possibility to identify/confirm structural differences in complex three‐dimensional polymeric structures. Scanning electron microscopy and swelling experiments in ethyl acetate respectively reveal an increase in the pore size (1.13 to 5.48 nm) and in the absorption ability of the elastomers cured with different types and quantities of PEG cross‐linker. The new elastomeric materials are exhibiting a rubbery state over a wide temperature range and absorptivity for the potential recovery of pollutants in soil and/or water. [ABSTRACT FROM AUTHOR]

Progress in protecting the equipment of mining and beneficiation enterprises, hydrotechnical structures from hydroabrasive wear is associated with the use and analysis of wear-resistant materials based on various polymer matrices: epoxy resins, polyurethanes, polyureas, and elastomers. The purpose of this study is a test and operational comparative assessment of hydroabrasive wear of up-to-date wear-resistant materials of domestic and foreign production under the action of the flow of solid particles of transported materials in the pulp. The dependence of hydroabrasive wear of wear-resistant materials on their polymer base was established, and it was shown that, taking into account the functionality of the application, the amount of wear during test trials and the performance of the finished products (sand nozzles of the HCC-710 hydrocyclone at the second stage of iron ore classification at the PJSC «Northern Mining and Processing Plant» (Kryvyi Rih)), epoxy composites are preferred. The influence of dispersion, hardness and shape features of hydroabrasive pulp particles on the wear of the best epoxy composites were clarified. It was shown that wear of epoxy composites obeys a linear time dependences in the initial stage of action of the pulp of different composition. A comparative evaluation hydroabrasive wear of the developed epoxy composite with multidisperse silicon carbide was carried out with the best foreign analogues (Belzona 1811, Great Britain, and Loctite 7219, Germany), and it was established that the developed composite is not inferior to them in this respect, being an order of magnitude lower cost. [ABSTRACT FROM AUTHOR]

Near‐infrared (NIR) mechanoluminescence (ML), capable of visualizing internal biological stress, is crucial for advancing in vivo bioimaging applications. Nonetheless, the scope of its applications is significantly constrained by the scarcity of available ML materials as well as unsatisfied ML efficiency. In this work, a NIR‐ML phosphor of Gd3Ga5O12: Cr3+ (GGO: Cr3+) is synthesized, which is characterized by a peak at 725 nm and a full width at half maximum (FWHM) of 100 nm. The NIR‐ML phenomenon of GGO: Cr3+ is demonstrated to stem from contact electrification generated by the interaction between the corresponding oxide powder and the employed elastomer. Accordingly, the NIR‐ML intensity is manipulated to be increased by 340%, attributed to the enhanced surface potential of GGO: Cr3+ for the incorporation of La3+ ions. Furthermore, the NIR‐ML of GGO: Cr3+/polydimethylsiloxane (PDMS) film performs excellent tissue penetration, which indicates its promising potential for in situ monitoring of biological stress. Hence, it paves the way for novel bioimaging within living organisms. [ABSTRACT FROM AUTHOR]

Liquid crystal elastomers (LCEs) are elastomeric networks with anisotropic monomers that reorient in response to applied loads, and in particular, thermomechanical loads. LCE complex microstructures translate into complex behaviors, such as soft elasticity, rate‐dependency, and hysteresis. In this work, we develop a three‐dimensional finite element implementation for monodomain LCEs, with the material modeled as a finite deformation viscoelastic network with a viscous director. The formulation is designed so that the director field can be modeled as an internal variable. Unique to this class of materials is that their deformation response function depends on the full deformation gradient and not just the right‐stretch tensor. This results in the material tangent losing its 'usual' symmetry properties. Accordingly, this makes the use of a first Piola–Kirchhoff finite element formulation advantageous. We utilize this framework to examine a number of nuances associated with the simulation and design of LCE based systems. In particular, we investigate in some detail the importance of a careful characterization of an LCE's initial director field. Via simulations of separate tension and compression experiments, we highlight the possibility of incorrect predictions when even small perturbations to initial conditions occur. The simulations are also used to illustrate the goodness of the model in replicating simple and complex experimental results, including the first‐of‐their‐kind buckling‐like column compression and thick‐walled balloon inflation simulations. [ABSTRACT FROM AUTHOR]

The vibrations generated in the two-wheeled vehicles like motorcycles due to road irregularities such as cracks, potholes, and bumps on the road cause discomfort for the rider as well as the pillion. These vibrations are reported to cause lower back pains, musculoskeletal effects, fatigue, and long-term health issues. Particularly, electric two-wheelers are more susceptible to these vibrations caused by the road and need attention. This paper presents an innovative technique for the reduction of vibrations at prominent locations in the electric two-wheeler to improve the rider's comfort. All measured accelerations are about vertical direction (along z-axis as per ISO 2631-1 standard). Passive and Semi-active damping treatments namely, Room temperature vulcanizing Silicone rubber and Magnetorheological elastomer (MRE) were applied on the test vehicle at strategic locations of vibration. Both were compared for their effectiveness in reducing the vibrations. Results showed that MRE based damping technique proved better vibration isolation at the strategic locations. The weighted root mean square acceleration as well as vibration dose values were found to decrease with the help of damping treatments thus improving the rider's overall comfort level. [ABSTRACT FROM AUTHOR]

Seismic isolation is a highly efficacious method for reducing the seismic load on structures. This technique is widely adopted to safeguard structures from earthquakes. Despite the promising results demonstrated by numerous isolation techniques, their implementation remains a significant challenge, particularly in developing countries, due to the high costs associated with manufacturing. Therefore, a novel and affordable base isolation technique has been proposed, namely unbonded mesh elastomeric layered isolator (UMELI). UMELI consists of steel mesh sandwiched between the unbonded layers of elastomers, resulting in an affordable isolator to be used for lightweight, low-rise structures. One of the crucial characteristics of this novel isolator is that it does not require a specialised manufacturing process unlike other elastomeric isolators. In the present study, experimental investigations are conducted to evaluate the dynamic characteristics such as dynamic vertical stiffness, equivalent lateral stiffness, and equivalent viscous damping ratio of UMELI. Its characteristics were studied for different layered isolators and are compared with the unreinforced elastomeric isolator. The investigations have demonstrated the effectiveness of the UMELI by increasing its vertical stiffness and reducing lateral stiffness, thereby enhancing the isolation period with the addition of a steel mesh layer. [ABSTRACT FROM AUTHOR]

Peripheral neural interfaces facilitate bidirectional communication between the nervous system and external devices, enabling precise control for prosthetic limbs, sensory feedback systems, and therapeutic interventions in the field of Bioelectronic Medicine. Intraneural interfaces hold great promise since they ensure high selectivity in communicating only with the desired nerve fascicles. Despite significant advancements, challenges such as chronic immune response, signal degradation over time, and lack of long-term biocompatibility remain critical considerations in the development of such devices. Here we report on the development and benchtop characterization of a novel design of an intraneural interface based on carbon fiber bundles. Carbon fibers possess low impedance, enabling enhanced signal detection and stimulation efficacy compared to traditional metal electrodes. We provided a 3D-stabilizing structure for the carbon fiber bundles made of PEDOT:PSS hydrogel, to enhance the biocompatibility between the carbon fibers and the nervous tissue. We further coated the overall bundles with a thin layer of elastomeric material to provide electrical insulation. Taken together, our results demonstrated that our electrode possesses adequate structural and electrochemical properties to ensure proper stimulation and recording of peripheral nerve fibers and a biocompatible interface with the nervous tissue. [ABSTRACT FROM AUTHOR]

The diverse applications of magnetorheological elastomer (MRE) drive efforts to understand consistent performance and resistance to failure. Stress relaxation can lead to molecular chain deterioration, degradation in stiffness and rheological properties, and ultimately affect the life cycle of MRE. However, quantifying the energy and molecular dynamics during stress relaxation is challenging due to the difficulty of obtaining atomic-level insights experimentally. This study employs molecular dynamics (MD) simulation to elucidate the stress relaxation in MRE during constant strain. Magnetorheological elastomer models incorporating silicone rubber filled with varying magnetic iron particles (50–80 wt%) were constructed. Experimental results from an oscillatory shear rheometer showed the linear viscoelastic region of MRE to be within 0.001–0.01% strain. The simulation results indicated that stress relaxation has occurred, with stored energies decreased by 8.63–52.7% in all MRE models. Monitoring changes in energy components, the highest final stored energy (12,045 kJ) of the MRE model with 80 wt% Fe particles was primarily attributed to stronger intramolecular and intermolecular interactions, revealed by higher potential energy (3262 kJ) and van der Waals energy (− 2717.29 kJ). Stress relaxation also altered the molecular dynamics of this MRE model as evidenced by a decrease in kinetic energy (9362 kJ) and mean square displacement value (20,318 Å2). The MD simulation provides a promising quantitative tool for elucidating stress relaxation, preventing material failure and offering insights for the design of MRE in the nanotechnology industry. [ABSTRACT FROM AUTHOR]

Polyurea elastomers exhibit superior mechanical properties due to their unique molecular structure, including significant tensile strength, elongation at break, and efficient energy absorption. Many studies have shown that polyurea elastomers can effectively reduce structural damage caused by blast loads, thus attracting widespread attention in the field of blast protection. This review presents a comprehensive analysis of the formulation optimization, energy absorption mechanism and the close relationship between microstructure and macroscopic properties of polyurea elastomers. Additionally, recent research advances in the blast resistance of sprayed polyurea elastomers in various protective structures are summarized. Finally, this review summarizes the current challenges in polyurea elastomer research and provides a forward-looking perspective on its future development. Future research should prioritize the design of formulations and material optimization to systematically study the factors influencing the protective performance of polyurea composite structures. It should also explore the application of advanced technologies in polyurea research to investigate the protection mechanisms at the microlevel. [ABSTRACT FROM AUTHOR]