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Many modern anti-icing and anti-fouling coatings rely on soft, low surface energy elastomeric materials such as polydimethylsiloxane for their functionality. While the low surface energy is desirable for reducing adhesion, very little work considers the larger contribution to adhesive failure caused by the viscoelastic nature of elastomers. Here we examine several different siloxane elastomers using a JKR adhesion test, which was operated over a range of different speeds and temperatures. Additionally, we characterize the dynamic mechanical modulus over a large range of frequencies for each material. We note that surface energies of the materials are all similar, but variation in adhesion strength is clear in the data. The variation at low speeds is related to elastomer architecture but the speed dependence itself is independent of architecture. Qualitative correlations are noted between the JKR adhesion measurements and the dynamic moduli. Finally, an attempt is made to directly compare moduli and adhesion through the recent Persson–Brener model. Approximations of the model are shown to be inaccurate. The full model is found to be accurate at low speeds, although it fails to precisely capture higher speed behaviour. [ABSTRACT FROM AUTHOR]

Cutting of soft materials is a complex problem, which is still not well understood at the fundamental level, especially for soft materials. The cutting process we consider is slicing, which starts with indentation, followed by sliding of a knife on the material to be cut. Here, we describe cutting experiments on PDMS elastomers with three different moduli. Our experiments reveal typical stages of this cutting process, starting with indentation and ending at steady state cutting. The process starts with a pre-cutting phase in which the blade does not slip grossly relative to the solid to be cut, and deformation is mostly elastic. Slip of the blade initiates suddenly and is often accompanied by initiation of cutting. Cutting is relatively smooth in the next stage, which requires a continuous increase in shear force. For soft PDMS, this smooth cutting stage is followed by one in which folds or creases form on the cutting surface. The corresponding shear force response is no longer smooth as "steady" sliding occurs in a stick–slip fashion with oscillatory forces. The average shear force reaches a plateau and no longer increases with shear displacement. Experimental observations of the various cutting stages are interpreted quantitatively. [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]

The industry's mechanical equipment often faces a significant demand for damping rubber. Simultaneously improving damping and toughness of rubber materials is a challenging task. It was achieved by incorporating crystal particles into the chlorinated butyl rubber (CIIR) network, inspired by the "sliding crystal mechanism". To create the elastomers with high damping and toughness, polyurethane was used along with polyethylene glycol as a soft segment. The combination factors, including coordination and hydrogen bonds, played a crucial role in facilitating the formation of crystal particles within the material. These crystal particles acted as rigid fillers, enhancing the material's toughness. Additionally, the sacrificial reversible bonds present in the crystal particles allowed for energy dissipation during stress. These bonds can be repeatedly broken and regenerated, enabling the material to dissipate energy efficiently. Comparing these elastomers to pure CIIR, they exhibited a tensile strength and elongation at break of 5.76 MPa and 1973%, a fracture energy of 28.73 MJ/m3, a damping factor of 1.52, and a damping temperature range of 80 °C. These results indicate significant improvements in both damping and toughness properties. This advancement could have valuable implications for the industry's mechanical equipment, which often relies on effective damping rubber. [ABSTRACT FROM AUTHOR]

The emergence of stretchable electronic technology has led to the development of many industries and facilitated many unprecedented applications, owing to its ability to bear various deformations. However, conventional solid elastomer substrates and encapsulation can severely restrict the free motion and deformation of patterned interconnects, leading to potential mechanical failures and electrical breakdowns. To address this issue, we propose a design strategy of porous elastomer substrate and encapsulation to improve the stretchability of serpentine interconnects in island-bridge structures. The serpentine interconnects are fully bonded to the elastomer substrate, while segments above circular pores remain suspended, allowing for free deformation and a substantial improvement in elastic stretchability compared to the solid substrates. The pores ensure unimpeded interconnect deformations, and moderate porosity provides support while maintaining the initial planar state. Compared to conventional solid configurations, finite element analysis (FEA) demonstrates a substantial enhancement of elastic stretchability (e.g. ≈9 times without encapsulation and ≈ 7 times with encapsulation). Uniaxial cyclic loading fatigue experiments validate the enhanced elastic stretchability, indicating the mechanical stability of the porous design. With its intrinsic advantages in permeability, the proposed strategy has the potential to offer insightful inspiration and novel concepts for advancing the field of stretchable inorganic electronics. [ABSTRACT FROM AUTHOR]

Liquid Crystal Elastomers (LCEs) are renowned for their reversible deformation capabilities. Yet, enhancing their mechanical strength while retaining such flexibility has posed a considerable challenge. To overcome this, we utilized 4D printing to develop an innovative composite of LCE with carbon fiber fabric (LCEC). This approach has notably increased the tensile strength of LCE by eightfold, all the while maintaining its exceptional capacity for reversible deformation. By adjusting the alignment angle between carbon fiber and the LCE printing direction from 0° to 90°, the LCEC demonstrates an array of new deformation patterns, including bending, twisting, wrapping, and S-shaped transformations, which are distinct from pure LCE materials. Our study unveils that LCE composites exhibit deformation processes markedly different from their pure material counterparts, with the ability of pure LCE to sustain tensile strains exceeding 1900%. These findings, previously undocumented and unexplored, represent a substantial contribution to the field of smart materials. Employing finite element analysis, we explored the carbon fiber and LCE matrix dynamics, revealing bending mechanics in LCECs. This combined experimental and simulation approach yields crucial insights for crafting durable, high-strength LCECs with diverse deformational properties, advancing smart material technology. [ABSTRACT FROM AUTHOR]

Regulation of phase structure has been recognized as one of the most effective ways to fabricate self-healing polymers with high mechanical strength. The mechanical properties of the resultant polymers are certainly affected by the size of separated phase domain. However, the study on this aspect is absence, because it can hardly exclude the influence of variation in monomer proportion required for tuning the separated phase size. Here, we report the first study on tuning the phase size through reversible addition-fragmentation chain transfer (RAFT) polymerization without changing the proportion of monomers. As expected, the size of separated phase has been successfully mediated from 15 nm to 9 nm by tuning the molecular weight of the chain transfer agent. It is found that the mechanical strength and the self-healing efficiency of the resultant polymers increase simultaneously with the decrease of phase size. The study on the formation kinetics of hydrogen bonds reveals that the decrease of phase size can facilitate the re-bonding rate of hydrogen bonds, even if the migration of polymer chains is restricted. [ABSTRACT FROM AUTHOR]

Rubbers or elastomers play an important role in hi-tech technology and civilian daily life because of their unique and strategical properties. Generally, the rubber additives are essential components for rubbers' practical application. Nowadays, developing novel multifunctional additives has attracted increasing research attention. In this work, low-cost crude carbon dots (CCDs) were used as multifunctional additives for natural rubber/silica system (without any additional modification) through industrial compatible melt-mixing method. The results revealed that the CCDs could disperse well in the NR/silica system, and they could not only endow the rubber compound with excellent anti-aging capability due to CCDs' radical scavenging activity because of their plenty of nitrogen-containing species, but also improve the curing rate and mechanical performance of the rubber composite. Also, the CCDs could reduce the rolling resistance of the rubber composites (tanδ value at 7% strain of the rubber composite could be decreased by 34%), which is promising for the application of energy-saving tire industry. Lastly, the addition of CCDs could effectively reduce the ZnO dosage by at least 40% in the rubber composite without deteriorating its performance. Overall, this work provides valuable guidance to develop novel cheap yet effective additives for the elastomer. [ABSTRACT FROM AUTHOR]

Thermoplastic elastomer gels based on styrenic triblock copolymers have been increasingly used as dielectric elastomers, particularly due to the possibility of tailoring their properties based on their composition. However, these materials have a low relative permittivity, primarily attributed to their low dipole moment. Consequently, this characteristic poses a challenge for their application as dielectric elastomers. In this work, we aim to assess the impact of adding kraft lignin on the dielectric properties of thermoplastic elastomer gels. Additionally, we investigate the effects of kraft lignin dispersion on their viscoelastic and mechanical properties. For this purpose, we used two types of kraft lignin: acidic and alkaline (ac-KL and alk-KL). The alk-KL demonstrated higher dispersibility in the polymer, mainly attributed to the deprotonation of its structure during its production process. As a result, the dielectric elastomer with alk-KL showed a 50% increase in relative permittivity compared to the pristine polymer without compromising its mechanical and viscoelastic properties. Moreover, these samples demonstrated a greater actuation strain capability in response to an electrical stimulus. Thus, the incorporation of lignin demonstrates promise as a valuable reinforcement in the development of advanced dielectric materials, enhancing their electro-mechanical performance. [ABSTRACT FROM AUTHOR]

In classical experiments, it has been found that a rigid cylinder can roll both on and under an inclined rubber plane with a friction force that depends on a power law of velocity, independent of the sign of the normal force. Further, contact area increases significantly with velocity with a related power law. We try to model qualitatively these experiments with a numerical boundary element solution with a standard linear solid and we find for sufficiently large Maugis–Tabor parameter λ qualitative agreement with experiments. However, friction force increases linearly with velocity at low velocities (like in the case with no adhesive hysteresis) and then decays at large speeds. Quantitative agreement with the Persson–Brener theory of crack propagation is found for the two power law regimes, but when Maugis–Tabor parameter λ is small, the cut-off stress in Persson–Brener theory depends on all the other dimensionless parameters of the problem. [ABSTRACT FROM AUTHOR]

Recycling of carbon fiber‐reinforced polymer composites (CFRCs) based on thermosetting plastics is difficult. In the present study, high‐performance CFRCs are fabricated through complexation of aromatic pinacol‐cross‐linked polyurethane (PU−AP) thermosets with carbon fiber (CF) cloths. PU−AP thermosets exhibit a breaking strength of 95.5 MPa and toughness of 473.6 MJ m−3 and contain abundant hydrogen‐bonding groups, which can have strong adhesion with CFs. Because of the high interfacial adhesion between CF cloths and PU−AP thermosets and high toughness of PU−AP thermosets, CF/PU−AP composites possess a high tensile strength of >870 MPa. Upon heating in N,N‐dimethylacetamide (DMAc) at 100 °C, the aromatic pinacols in the CF/PU−AP composites can be cleaved, generating non‐destructive CF cloths and linear polymers that can be converted to high‐performance elastomers. The elastomers are mechanically robust, healable, reprocessable, and damage‐resistant with an extremely high tensile strength of 74.2 MPa and fracture energy of 149.6 kJ m−2. As a result, dissociation of CF/PU−AP composites enables the recovery of reusable CF cloths and high‐performance elastomers, thus realizing the upcycling of CF/PU−AP composites. [ABSTRACT FROM AUTHOR]

Recycling of carbon fiber‐reinforced polymer composites (CFRCs) based on thermosetting plastics is difficult. In the present study, high‐performance CFRCs are fabricated through complexation of aromatic pinacol‐cross‐linked polyurethane (PU−AP) thermosets with carbon fiber (CF) cloths. PU−AP thermosets exhibit a breaking strength of 95.5 MPa and toughness of 473.6 MJ m−3 and contain abundant hydrogen‐bonding groups, which can have strong adhesion with CFs. Because of the high interfacial adhesion between CF cloths and PU−AP thermosets and high toughness of PU−AP thermosets, CF/PU−AP composites possess a high tensile strength of >870 MPa. Upon heating in N,N‐dimethylacetamide (DMAc) at 100 °C, the aromatic pinacols in the CF/PU−AP composites can be cleaved, generating non‐destructive CF cloths and linear polymers that can be converted to high‐performance elastomers. The elastomers are mechanically robust, healable, reprocessable, and damage‐resistant with an extremely high tensile strength of 74.2 MPa and fracture energy of 149.6 kJ m−2. As a result, dissociation of CF/PU−AP composites enables the recovery of reusable CF cloths and high‐performance elastomers, thus realizing the upcycling of CF/PU−AP composites. [ABSTRACT FROM AUTHOR]

Liquid crystal elastomers (LCEs) are responsive materials that can undergo large reversible deformations upon exposure to external stimuli, such as electrical and thermal fields. Controlling the alignment of their liquid crystals mesogens to achieve desired shape changes unlocks a new design paradigm that is unavailable when using traditional materials. While experimental measurements can provide valuable insights into their behavior, computational analysis is essential to exploit their full potential. Accurate simulation is not, however, the end goal; rather, it is the means to achieve their optimal design. Such design optimization problems are best solved with algorithms that require gradients, i.e., sensitivities, of the cost and constraint functions with respect to the design parameters, to efficiently traverse the design space. In this work, a nonlinear LCE model and adjoint sensitivity analysis are implemented in a scalable and flexible finite element-based open source framework and integrated into a gradient-based design optimization tool. To display the versatility of the computational framework, LCE design problems that optimize both the material, i.e., liquid crystal orientation, and structural shape to reach a target actuated shapes or maximize energy absorption are solved. Multiple parameterizations, customized to address fabrication limitations, are investigated in both 2D and 3D. The case studies are followed by a discussion on the simulation and design optimization hurdles, as well as potential avenues for improving the robustness of similar computational frameworks for applications of interest. [ABSTRACT FROM AUTHOR]

Poly (glycerol sebacate) is a widely studied elastomeric copolymer obtained from the polycondensation of two bioresorbable monomers, glycerol and sebacic acid. Due to its biocompatibility and the possibility to tailor its biodegradability rate and mechanical properties, PGS has gained lots of interest in the last two decades, especially in the soft tissue engineering field. Different synthetic approaches have been proposed, ranging from classic thermal polyesterification and curing to microwave-assisted organic synthesis, UV crosslinking and enzymatic catalysis. Each technique, characterized by its advantages and disadvantages, can be tailored by controlling the crosslinking density, which depends on specific synthetic parameters. In this work, classic and alternative synthetic methods, as well as characterisation and tailoring techniques, are critically reviewed with the aim to provide a valuable tool for the reproducible and customized production of PGS for tissue engineering applications. [ABSTRACT FROM AUTHOR]

Elastomers are made of chain-like molecules to form networks that can sustain large deformation. Rubbers are thermosetting elastomers that are obtained from irreversible curing reactions. Curing reactions create permanent bonds between the molecular chains. On the other hand, thermoplastic elastomers do not need curing reactions. Incorporation of appropriated filler particles, as has been practiced for decades, can significantly enhance mechanical properties of elastomers. However, there are fundamental questions about polymer matrix composites (PMCs) that still elude complete understanding. This is because the macroscopic properties of PMCs depend not only on the overall volume fraction (ϕ) of the filler particles, but also on their spatial distribution (i.e., primary, secondary, and tertiary structure). This work aims at reviewing how the mechanical properties of PMCs are related to the microstructure of filler particles and to the interaction between filler particles and polymer matrices. Overall, soft rubbery matrices dictate the elasticity/hyperelasticity of the PMCs while the reinforcement involves polymer–particle interactions that can significantly influence the mechanical properties of the polymer matrix interface. For ϕ values higher than a threshold, percolation of the filler particles can lead to significant reinforcement. While viscoelastic behavior may be attributed to the soft rubbery component, inelastic behaviors like the Mullins and Payne effects are highly correlated to the microstructures of the polymer matrix and the filler particles, as well as that of the polymer–particle interface. Additionally, the incorporation of specific filler particles within intelligently designed polymer systems has been shown to yield a variety of functional and responsive materials, commonly termed smart materials. We review three types of smart PMCs, i.e., magnetoelastic (M-), shape-memory (SM-), and self-healing (SH-) PMCs, and discuss the constitutive models for these smart materials. [ABSTRACT FROM AUTHOR]

Magnetorheological elastomers (MREs) are a class of smart materials with rubber-like qualities, demonstrating revertible magnetic field-dependent viscoelastic properties, which makes them an ideal candidate for development of the next generation of adaptive vibration absorbers. This research study aims at the development of a finite element model using microscale representative volume element (RVE) approach to predict the field-dependent shear behavior of MREs. MREs with different elastomeric matrices, including silicone rubber Ecoflex 30 and Ecoflex 50, and carbonyl iron particles (CIPs) have been considered as magnetic particles. The stress–strain characteristic of the pure silicon rubbers was evaluated experimentally to formulate the nonlinear Ogden strain energy function to describe hyper-elastic behavior of the rubbery matrix. The obtained mechanical and magnetic properties of the matrix and inclusions were integrated into COMSOL Multiphysics to develop the RVE for the MREs, in 2D and 3D configurations, with CIP volume fraction varying from 5% to 40%. Periodic boundary condition (PBC) was imposed on the RVE boundaries, while undergoing shear deformation subjected to magnetic flux densities of 0–0.4 T. Comparing the results from 2D and 3D modeling of isotropic MRE-RVE with the experimental results from the literature suggests that the 3D MRE-RVE can be effectively used to accurately predict the influence of varying factors including matrix type, volume fraction of magnetic particles, and applied magnetic field on the mechanical behavior of MREs. [ABSTRACT FROM AUTHOR]

The development of stretchable electronic devices is a critical area of research for wearable electronics, particularly electronic textiles (e-textiles), where electronic devices embedded in clothing need to stretch and bend with the body. While stretchable electronics technologies exist, none have been widely adopted. This work presents a novel and potentially transformative approach to stretchable electronics using a ubiquitous structure: the helix. A strip of flexible circuitry ('e-strip') is twisted to form a helical ribbon, transforming it from flexible to stretchable. A stretchable core—in this case rubber cord—supports the structure, preventing damage from buckling. Existing helical electronics have only extended to stretchable interconnects between circuit modules, and individual components such as printed helical transistors. Fully stretchable circuits have, until now, only been produced in planar form: flat circuits, either using curved geometry to enable them to stretch, or using inherently stretchable elastomer substrates. Helical e-strips can bend along multiple axes, and repeatedly stretch between 30 and 50%, depending on core material and diameter. LED and temperature sensing helical e-strips are demonstrated, along with design rules for helical e-strip fabrication. Widely available materials and standard fabrication processes were prioritized to maximize scalability and accessibility. [ABSTRACT FROM AUTHOR]

The progress of stretchable and wearable photovoltaics relies heavily on intrinsically stretchable active layer films. Nevertheless, there is a paucity of research clarifying the connections between their microstructure, performance, and their adaptation to large strain in polymer electronic films. The current study utilizes multiple synchrotron X‐ray scattering methods to collectively examine the correlations between morphology and stretchability, as well as the microstructural evolution induced by stretching in three sample cases of highly stretchable ternary blend films. These blends contain over 30% by weight of a polymer elastomer, such as styrene‐ethylene‐butylene‐styrene block copolymer, integrated into the high‐performance polymer:nonfullerene small molecule mixture. Specifically, the real‐time microstructural changes of these durable organic photovoltaic films with elastomers are monitored when subjected to tensile stretching through in situ synchrotron X‐ray scattering. The experiments demonstrate that polymeric elastomers can effectively lower the degree of crystallinity in films and deform the crystallites of semiconductor molecules. The elastomeric component aids in stress dispersion during stretching, thereby improving the microstructural durability of blend films. This study provides new recommendations for advancing stretchable organic optoelectronic devices. [ABSTRACT FROM AUTHOR]

Loops are prevalent topological structures in cross‐linked polymer networks, resulting from the folding of polymer chains back onto themselves. Traditionally, they have been considered as defects that compromise the mechanical properties of the network, leading to extensive efforts in synthesis to prevent their formation. In this study, we introduce the inclusion of cyclic dibenzo‐24‐crown‐8 (DB24C8) moieties within the polymer network strands to form CCNs, and surprisingly, these loops enhance the mechanical performances of the network, leading to tough elastomers. The toughening effect can be attributed to the unique cyclic structure of DB24C8. The relatively small size and the presence of rigid phenyl rings provide the loops with relatively stable conformations, allowing for substantial energy dissipation upon the application of force. Furthermore, the DB24C8 rings possess a broad range of potential conformations, imparting the materials with exceptional elasticity. The synergistic combination of these two features effectively toughens the materials, resulting in a remarkable 66‐fold increase in toughness compared to the control sample of covalent networks. Moreover, the mechanical properties, particularly the recovery performance of the network, can be effectively tuned by introducing guests to bind with DB24C8, such as potassium ions and secondary ammonium salts. [ABSTRACT FROM AUTHOR]

Vibrations with various frequencies in daily life and industry can cause health hazards and fatigue failure of critical structures, which requires the development of elastomers with high energy dissipation at desired frequencies. Current strategies relying on tuning characteristic relaxation time of polymer chains are mostly qualitative empirical methods, and it is difficult to precisely control damping performances. Here, we report a general strategy for constructing dynamic crosslinked polymer fluid gels that provide controllable ultrahigh energy dissipation. This is realized by dynamic‐bond‐mediated chain reptation of polymer fluids in a crosslinked network, where the characteristic time of chain reptation is dominated by the presence of well‐defined dissociation time of dynamic bonds and almost independent of their molar mass. Using prototypical supramolecular polydimethylsiloxane elastomers, we demonstrate that dynamic crosslinked polymer fluid gels exhibit a controllable ultrahigh damping performance at desired frequencies (10−2~102 Hz), exceeding that of typical state‐of‐the‐art silicone damping materials. Their shock absorption is over 300 % higher than that of commercial silicone rubber under the same impact force. [ABSTRACT FROM AUTHOR]

Loops are prevalent topological structures in cross‐linked polymer networks, resulting from the folding of polymer chains back onto themselves. Traditionally, they have been considered as defects that compromise the mechanical properties of the network, leading to extensive efforts in synthesis to prevent their formation. In this study, we introduce the inclusion of cyclic dibenzo‐24‐crown‐8 (DB24C8) moieties within the polymer network strands to form CCNs, and surprisingly, these loops enhance the mechanical performances of the network, leading to tough elastomers. The toughening effect can be attributed to the unique cyclic structure of DB24C8. The relatively small size and the presence of rigid phenyl rings provide the loops with relatively stable conformations, allowing for substantial energy dissipation upon the application of force. Furthermore, the DB24C8 rings possess a broad range of potential conformations, imparting the materials with exceptional elasticity. The synergistic combination of these two features effectively toughens the materials, resulting in a remarkable 66‐fold increase in toughness compared to the control sample of covalent networks. Moreover, the mechanical properties, particularly the recovery performance of the network, can be effectively tuned by introducing guests to bind with DB24C8, such as potassium ions and secondary ammonium salts. [ABSTRACT FROM AUTHOR]

Vibrations with various frequencies in daily life and industry can cause health hazards and fatigue failure of critical structures, which requires the development of elastomers with high energy dissipation at desired frequencies. Current strategies relying on tuning characteristic relaxation time of polymer chains are mostly qualitative empirical methods, and it is difficult to precisely control damping performances. Here, we report a general strategy for constructing dynamic crosslinked polymer fluid gels that provide controllable ultrahigh energy dissipation. This is realized by dynamic‐bond‐mediated chain reptation of polymer fluids in a crosslinked network, where the characteristic time of chain reptation is dominated by the presence of well‐defined dissociation time of dynamic bonds and almost independent of their molar mass. Using prototypical supramolecular polydimethylsiloxane elastomers, we demonstrate that dynamic crosslinked polymer fluid gels exhibit a controllable ultrahigh damping performance at desired frequencies (10−2~102 Hz), exceeding that of typical state‐of‐the‐art silicone damping materials. Their shock absorption is over 300 % higher than that of commercial silicone rubber under the same impact force. [ABSTRACT FROM AUTHOR]

[Display omitted] As ideal and smart stimuli-responsive materials for soft actuators, artificial muscles, etc., liquid crystalline elastomers (LCEs) can respond to external stimuli, including heat, light, electricity, magnetism, humidity, etc., and make corresponding deformations. Among these external stimuli, magnetic stimulus is featured by remote and contactless control, fast, precise, extremely strong penetration, safe, easy tunability, and so on. By doping magnetic nanoparticles into LCEs, their actuation and motion can be triggered by magnetic fields or forces untetheredly, remotely, and highly precisely. Therefore, the magnetic nanoparticles endow LCEs with magneto-responsiveness, opening doors to LCEs for many unique potential uses, such as magnetic read-out, magnetic valves, magnetic switches, and so on. This review summarizes recent advances in magneto-responsive LCE nanocomposites. Their fabrication is comprehensively discussed. New properties of magneto-responsive LCEs brought by magnetic nanoparticles are also thoroughly reviewed. Their promising applications are subsequently summarized and explored. [ABSTRACT FROM AUTHOR]

A Dielectric Elastomer Actuator (DEA) consists of electrodes with a dielectric layer between them. By controlling the design of the electrodes, voltage, and frequency, the operating range and speed of the DEA can be adjusted. These DEAs find applications in biomimetic robots, artificial muscles, and similar fields. When voltage is applied to the DEA, the dielectric layer undergoes compression and expansion due to electrostatic forces, which can lead to electrical breakdown. This phenomenon is closely related to the performance and lifespan of the DEA. To enhance stability and improve dielectric properties, a DEA Reservoir layer is introduced. Here, stability refers to the ability of the DEA to perform its functions even as the applied voltage increases. The Reservoir layer delays electrical breakdown and enhances stability due to its enhanced thickness. The proposed DEA in this paper is composed of a Reservoir layer and electrode layer. The Reservoir layer is placed between the electrode layers and is independently configured, not subjected to applied voltage like the electrode layers. The performance of the DEA was evaluated by varying the number of polymer layers in the Reservoir and electrode designs. Introducing the Reservoir layer improved the dielectric properties of the DEA and delayed electrical breakdown. Increasing the dielectric constant through the DEA Reservoir can enhance output characteristics in response to electrical signals. This approach can be utilized in various applications in wearable devices, artificial muscles, and other fields. [ABSTRACT FROM AUTHOR]

The rapid development of 3D printing technology and the emerging applications of shape memory elastomer have greatly stimulated the research of photocurable polymers. In this work, glycerol (Gly) was polycondensed with sebacic, dodecanedioic, or tetradecanedioic acids to provide precursor polyesters with hydroxyl or carboxyl terminal groups, which were further chemically functionalized by acryloyl chloride to introduce sufficient, photocurable, and unsaturated double bonds. The chemical structures of the acrylated polyesters were characterized by FT IR and NMR spectroscopies. The photoinitiated crosslinking behavior of the acrylated polyesters under ultraviolet irradiation without the addition of any photoinitiator was investigated. The results showed that the precursor polyesters that had a greater number of terminated hydroxyls and a less branched structure obtained a relatively high acetylation degree. A longer chain of aliphatic dicarboxylic acids (ADCAs) and higher ADCA proportion lead to a relatively lower photopolymerization rate of acrylated polyesters. However, the photocured elastomers with a higher ADCA proportion or longer-chain ADCAs resulted in better mechanical properties and a lower degradation rate. The glass transition temperature (Tg) of the elastomer increased with the alkyl chain length of the ADCAs, and a higher Gly proportion resulted in a lower Tg of the elastomer due to its higher crosslinking density. Thermal gravimetric analysis (TGA) showed that the chain length of the ADCAs and the molar ratio of Gly to ADCAs had less of an effect on the thermal stability of the elastomer. As the physicochemical properties can be adjusted by choosing the alkyl chain length of the ADCAs, as well as changing the ratio of Gly:ADCA, the photocurable polyesters are expected to be applied in multiple fields. [ABSTRACT FROM AUTHOR]

Transparent polysiloxane elastomers with good self-healing and reprocessing abilities have attracted significant attention in the field of artificial skin and flexible displays. Herein, we propose a simple one-pot method to fabricate a room temperature self-healable polysiloxane elastomer (HPDMS) by introducing dynamic and reversible imine bonds and boroxine into polydimethylsiloxane (PDMS) networks. The presence of imine bonds and boroxine is proved by FT−IR and NMR spectra. The obtained HPDMS elastomer is highly transparent with a transmittance of up to 80%. The TGA results demonstrated that the HPDMS elastomer has good heat resistance and can be used in a wide temperature range. A lower glass transition temperature (Tg, −127.4 °C) was obtained and revealed that the elastomer is highly flexible at room temperature. Because of the reformation of dynamic reversible imine bonds and boroxine, the HPDMS elastomers exhibited excellent autonomous self-healing properties. After healing for 3 h, the self-healing efficiency of HPDMS reached 96.3% at room temperature. Moreover, the elastomers can be repeatedly reprocessed multiple times under milder conditions. This work provides a simple but effective method to prepare transparent self-healable and reprocessable polysiloxane elastomers. [ABSTRACT FROM AUTHOR]

Elastomer composites for dynamic mechanical applications with a low dissipation of energy are of great importance in view of their application in tire compounds. In this work, furnace carbon black functionalized with 2-2,5-dimethyl-1H-pyrrol-1-yl-1,3-propanediol (SP) was used in place of silica in an elastomer composite based on poly(styrene-co-butadiene) from solution anionic polymerization and poly(1,4-cis-isoprene) from Hevea Brasiliensis. The traditional coupling agent used for silica was also used for the CB/SP adduct: 3,3′-bis(triethoxysilylpropyl)tetrasulfide (TESPT). The composite with the CB/SP + TESPT system revealed a lower Payne effect, higher dynamic rigidity, and lower hysteresis, compared to the composite with CB + TESPT, although the latter composite had a higher crosslinking density. The properties of the silica and the CB/SP + TESPT-based composites appear similar, though in the presence of slightly higher hysteresis and lower ultimate properties for the CB/SP-based composite. The use of CB in place of silica allows us to prepare lighter compounds and paves the way for the preparation of tire compounds with lower environmental impacts. [ABSTRACT FROM AUTHOR]

Silicone elastomers are high-performance plastics. In the extrusion process, only high-consistency silicone rubbers were used. In order to reduce the cost and weight, silicone rubbers can be foamed during processing. In this study, high-consistency silicone rubber is processed with different physical and chemical blowing agents. The resulting reaction kinetics, as well as the mechanical and morphological properties, had been investigated and compared with each other. This showed that the chemical blowing agent significantly influenced the crosslinking reaction compared to the microspheres and the water/silica mixture tested, but it also achieved the lowest density compared to the physical blowing agents. When evaluating the foam morphology, it became clear that the largest number of pores was achieved with the microspheres and the largest pores when using the water/silica mixture. Furthermore, it has been shown that the different mechanisms of action of the blowing agents have a major influence on the mechanical properties, such as the micro shore hardness and the foam morphology. [ABSTRACT FROM AUTHOR]

In nature, spider web is an interwoven network with high stability and elasticity from silk threads secreted by spider. Inspired by the structure of spider webs, light‐driven liquid crystal elastomer (LCE) active yarn is designed with super‐contractile and robust weavability. Herein, a novel biomimetic gold nanorods (AuNRs) @LCE yarn soft actuator with hierarchical structure is fabricated by a facile electrospinning and subsequent photocrosslinking strategies. Meanwhile, the inherent mechanism and actuation performances of the as‐prepared yarn actuator with interleaving network are systematically analyzed. Results demonstrate that thanks to the unique "like‐spider webs" structure between fibers, high molecular orientation within the LCE microfibers and good flexibility, they can generate super actuation strain (≈81%) and stable actuation performances. Importantly, benefit from the robust covalent bonding at the organic–inorganic interface, photopolymerizable AuNRs molecules are uniformly introduced into the polymer backbone of electrospun LCE yarn to achieve tailorable shape‐morphing under different light intensity stimulation. As a proof‐of‐concept illustration, light‐driven artificial muscles, micro swimmers, and hemostatic bandages are successfully constructed. The research disclosed herein can offer new insights into continuous production and development of LCE‐derived yarn actuator that are of paramount significance for many applications from smart fabrics to flexible wearable devices. [ABSTRACT FROM AUTHOR]

To date, a diverse array of smart materials, drawing inspiration from nature, is developed, exhibiting remarkable shape or color‐changing capabilities, which hold great promise in applications such as bionic soft robots and information encryption platforms. Achieving reversible shape‐shifting and color variation harmoniously within a single material is a particularly appealing prospect. Herein, a facile approach to creating such materials is presented, capable of undergoing reversible shape and color‐change synchronously. This is achieved by harnessing the stress‐free two‐way shape‐memory effect (2W‐SME) of a liquid crystal elastomer (LCE), meticulously programmed at both macro and micro scales. Specifically, the LCE with stress‐free 2W‐SME is fabricated, and permanent grating nanostructures are meticulously constructed through UV‐assisted nanoimprinting. By enabling reversible shape alterations at multiple dimensions, encompassing both macro and micro scales, the LCE material concurrently exhibits reversible changes in shape and color, triggered by heat. As a result, intelligent information encryption and decryption platforms that leverage the unique capabilities of LCE are demonstrated. The outcomes of this research endeavor are poised to pave the way for the advancement of smart materials in the realms of data storage and encryption. [ABSTRACT FROM AUTHOR]

The electrically‐directed, isothermal response of liquid crystal elastomers (LCEs) to an applied electric field is a compelling approach to realize spatially tailorable, sequence‐controllable, and high‐frequency deformation. The electromechanical response is facilitated by coating aligned LCEs with compliant electrodes. Upon application of an electric field, the electrodes attract and generate Maxwell stress. The directional difference in moduli for aligned LCEs produces directional deformation of the material and does not require mechanical bias or framing. Here, LCEs prepared from a newly reported thiol‐ene reaction are explored as DEAs with improved mechanical and dielectric properties. This report details that incorporating a difunctional liquid crystalline monomer composed of allyl ether functional groups reduces Young's modulus, increases the dielectric constant, and improves cyclic recovery compared to an analogous LCE prepared by thiol‐ene polymerization. Electrically‐induced, isothermal deformation of as much as 30% strain is reported. The facile chemistry and enhanced electromechanical response reported here may enable the functional integration of LCEs in applications such as robotics. [ABSTRACT FROM AUTHOR]

The Rivlin-Thomas classical energy balance model for tearing tests suggests that the fracture energy G is proportional to the work of the external load in the legs (potential energy), for not too large stretches in the legs, so the increase of G with loading rate is observed or measured, but not really explained by the model. Shrimali and Lopez-Pamies (SLP) have recently built a theory on viscoelastic fracture from recent experimental evidence of a critical (stretch rate-independent) stretch on nucleation of cracks in the pure shear tests. The theory in other words incorporates this evidence in an otherwise energy-based criterion. In the paper "The trousers fracture test for viscoelastic elastomers" (ASME J. Appl. Mech., 2023, 90(7), p. 071010), they seem to obtain the critical (stretch rate-independent) stretch condition for the case of trouser tests (applying their theory from a long enough crack) both in nucleation and steady-state propagation. This outcome seems reasonable since for a linear material, looking at the elastic limit cases of very slow and very fast rates, it would produce an increase of the load, and hence of the fracture energy, proportional to the increase of the modulus, which is in line with what has been found experimentally, although possibly in contrast with classical rate-independent cohesive models, at least for crack nucleation. [ABSTRACT FROM AUTHOR]

Snap-through instabilities in single and interconnected dielectric elastomer actuators have demonstrated their potential in enabling many functionalities such as large deformation, high-speed actuation, and enhanced flowrates in fluid pumps. However, the nonlinear nature of dielectric elastomers and the complex interplay of mechanics in interconnected inflated actuators, make the modeling of such systems challenging. In this paper, we present a methodology to analytically model the instabilities in a system of three interconnected homogeneous spherical dielectric elastomer actuators through graphical and numerical approaches. The simulation results reveal the presence of a locus of initial stable states that the interconnected actuators can achieve at zero voltage. In specific loading conditions, the system exhibits multiple stable states which can be cyclically transitioned between by selectively applying voltage to specific actuators. In other conditions, the system may undergo two successive instabilities when the voltage applied to a single actuator in the system is increased monotonically. These results retrieve existing experimental results theoretically for the first time and identify a new behavior of cascading instabilities in inflated dielectric elastomer actuators. We hope this work will pave the way for programmable design of multistable systems to unravel new capabilities in dielectric elastomer actuators and soft robotics. [ABSTRACT FROM AUTHOR]

Stretchable inorganic electronics have been of growing interest over the past decades due to their various attractive potential applications. The island-bridge structure is the most widely used structural design, where rigid inorganic devices (islands) and interconnects (bridges) are attached to an elastomer substrate, and large deformations in the structure are accommodated by the large stretchability of the interconnects and the elastomer underneath them. Due to the large modulus mismatch of more than five orders of magnitude between the rigid island and elastomer substrate, there is a severe stress and strain concentration at the interface between the island and the substrate during large deformations, which may cause the interface fracture and delamination. In this work, the analytical solution of the interfacial shear and peel stress between the island and the substrate is derived to reveal the mechanism of interface fracture and agrees well with finite element analysis (FEA) results. A simple porous partition substrate design strategy is proposed to alleviate this stress and strain concentration at the boundary of the interface, where the porous region can undergo larger deformation due to the reduced stiffness of the material. FEA obtains the key parameters affecting the pore layout. The digital image correlation (DIC) experiment verifies the design strategy. The results show that, compared to the solid substrate, the porous partition substrate strategy can significantly reduce the maximum normal strain of the substrate around the island, thus effectively reducing the risk of structural interface failure. [ABSTRACT FROM AUTHOR]

In this study, a novel iron-based catalyst system, Fe(acac)3/(isocyanoimino) triptenylphosphorane (IITP)/AlR3, was employed for the synthesis of syndiotactic 1,2-polybutadiene in hexane. This catalyst system exhibits remarkably high catalytic activity, achieving a polymerization activity of 762 kgpolymer·molcatalyst−1·h−1 at 50 °C with a [BD]/[Fe] molar ratio of 20000. Furthermore, living polymerization characteristic were observed during the investigation of the polymerization kinetics of 1,3-butadiene polymerization. These characteristics were well demonstrated by a narrow molecular weight distribution (PDI≈2.0) of the resulting polybutadiene and a linear relationship between–ln(1 − c) and polymerization time as well as number average molecular weight and polymer yield. The resultant polymer showed a 1,2-selectivity of approximately 76% and stereoregularity ranging from 62% to 73%(rrrr). Additionally, through kinetic studies on polymerization reaction, an apparent activation energy Ea value of this catalytic system was calculated to be 84.98 kJ·mol−1, which suggests that high polymerization temperature favors efficient polymerization. [ABSTRACT FROM AUTHOR]

For practicable elastomeric polyethylene, achieving high catalyst thermal stability and activity, along with precise control of polymer properties such as branching density, molecular weights, and distribution, is crucial but challenging. In this study, two sets of symmetrical α-diimine nickel complexes, each comprising four nickel bromide or chloride complexes, were synthesized and investigated their performance for ethylene polymerization under various reaction conditions. Upon activation with either Et2AlCl or MMAO cocatalysts, these complexes displayed not only high activity but also generated high molecular weight polyethylenes with controlled polydispersity and a substantial number of branches. The catalyst with the least steric hindrance displayed the remarkable high activity (up to 1.2×107 g·mol−1·h−1). Notably, nickel bromides demonstrated higher activity compared to their chloride counterparts. The investigation into the effect of reaction temperature on catalytic performance revealed that NiBrMe-MMAO system displayed high thermal stability (activity up to 2.51×106 g·mol−1·h−1 at 100 °C) and consistently yielded high polymer molecular weights with narrow polydispersity over a broad temperature range of 30–100 °C. Of significant note, mechanical analysis of the resulting polyethylene demonstrated excellent ultimate tensile strength and high strain at break. Particularly, the polyethylene sample prepared at 100 °C exhibited ultimate tensile strength up to 10 MPa with 1863% maximum strain at break and a strain recovery of up to 54.9% after ten cycles at a fixed strain of 300%, indicating excellent material properties of prepared thermoplastic polyethylene elastomers (TPE). [ABSTRACT FROM AUTHOR]

Polyurethane (PU) is a versatile polymer with many applications in a wide range of products. A novel 3D printing technology called liquid additive manufacturing (LAM) extended its possibilities by generating PU elastomers with gradient properties in continuous processing. LAM, being a relatively new technique, has not been extensively researched, particularly in terms of the curing behavior of the liquid resin. In this work, we investigated the effect of composition on gelation time tGP as measured by time-resolved mechanical spectroscopy (TRMS) and analyzed using the Winter–Chambon criterion with the assistance of the IRIS software. This method is more accurate than the previous approach, which involved time sweeps with a constant frequency. It was found that the gel time tGP first decreased and then increased with increasing polyol ratio, ranging from 231 to 378 min. Furthermore, the crosslink densities of the different PU elastomers measured from the rheological and tensile tests were calculated and compared based on the theory of rubber elasticity. The crosslink density decreased with an increasing polyol ratio in both methods. However, the crosslink density values obtained from the rheological measurements were higher than those from the tensile tests. These findings demonstrate that adjusting the polyol ratio is an effective means of achieving gradient properties. The composition effects we measured offer valuable insights for the design of LAM–PU elastomers. [ABSTRACT FROM AUTHOR]

The emerging self-healing concept in rubber materials appears to be a good option for reducing rubber waste since it can enhance the longevity of the product's structure in conjunction with standard development goals to ensure sustainable consumption and efficient use of resources. Self-healing elastomers are fabricated to heal cracks and damage both at the micro and macroscopic levels to restrict failure by incorporating healing agents extrinsically or intrinsically. The major successful techniques to fabricate self-healing rubber were reviewed. The review also focuses on testing and analysis methods to understand the healing phenomena and quantification methods to measure the healing performance. The review also includes an overview of the self-healing elastomers for tyre applications. [ABSTRACT FROM AUTHOR]

The aim of this study is to explore a method for modifying waste brick powder (WBP) in order to reapply it to rubber products for effective resource recycling. Firstly, we use the auto polymerization of catechol/polyamine (CPA) on the surface of WBP to form a poly catechol/polyamine (PCPA) coating as an intermediate reaction platform. And then the macromolecular modifier, epoxy-functionalized elastomer (ethylene vinyl acetate-glycidyl methacrylate terpolymer) (EVMG), is further grafted onto the PCPA coating to prepare the WBP@EVMG hybrid materials. During the preparation of the WBP@EVMG hybrid materials, a ring-opening reaction between the amine group of PCPA and the epoxy group of EVMG occurs. The NR/WBP@EVMG composites are prepared by mechanical blending. The interfacial interactions between WBP@EVMG and NR are analyzed and verified in detail by dynamic mechanical analysis (DMA) and rubber process analyzer (RPA). It is shown that the modified NR/WBP composites show increased vulcanization rate and better mechanical properties, and the tensile strength, abrasion resistance, cracking strength, and wet slip resistance of NR/WBP@EVMG-15 are increased by 29%, 6%, 16%, and 11%, respectively, compared with that of NR/WBP composites, which provides a unique idea for the reuse of waste brick powder in rubber. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Poly(3‐hydroxybutyrate), a crucial member of the large biodegradable polyhydroxyalkanoate family, suffers from its brittleness. To enhance its performance, we employed a straightforward approach involving the ring‐opening copolymerization of racemic‐β‐butyrolactone (rac‐β‐BL) and β‐propiolactone (β‐PL) using the syndio‐selective amino‐alkoxy‐bis(phenolate)‐yttrium complex as a catalyst, thanks to the excellent ductility of poly(3‐hydroxypropionate). Control over the rac‐β‐BL/β‐PL feeding ratios and polymerization time yielded random or block copolymers with tunable thermal and mechanical properties comparable to traditional fossil‐based plastics. Furthermore, we achieved one‐pot synthesis of hard‐soft‐hard triblock copolymers by exploiting monomers' different copolymerization rates and a bifunctional initiator, thus transforming polyhydroxyalkanoates from hard and tough plastics to soft and ductile thermoplastic elastomers. [ABSTRACT FROM AUTHOR]

A viscoelastic constitutive model constructed with fractional derivatives can accurately describe the mechanical phenomena caused by materials with time-dependent and memory properties. Using this model, the vibration characteristics and stability of a functionally graded fractional derivative viscoelastic fluid–conveying pipe with initial geometric defects are investigated in this study. First, the differential equation of motion for a functionally graded fractional derivative viscoelastic fluid–conveying pipe with initial geometric defects is derived by applying the Hamilton principle. Dimensionless differential equations and boundary conditions are discretized using a differential quadrature method, and numerical solutions of the equations under three boundary conditions are obtained. Further, the effects of geometric defect types, fractional order, power law exponent, and other factors on the complex frequency of this fluid-conveying pipe are discussed. The findings revealed that the geometric defects of the fluid-conveying pipe can significantly affect the complex frequency of the system. Moreover, the pipe's damping characteristics vary with the fractional order of the viscoelastic material. In other words, the higher the vibration mode of the pipe, the more susceptible it is to the fractional order. Because the fractional derivative relates to values near the current moment and overall history, it can effectively describe the temporal effect of materials, such as polymers, synthetic rubber, and coatings. Many naturally occurring materials (including geological materials such as soil, oil, and minerals and biological materials such as muscle, bone, and blood) exhibit time-dependent properties. The deformation of such materials relates to the current stress level and their overall history. Because the fractional derivative constitutive relation can describe the dynamic properties of a structure in a wide frequency range with only a few parameters and terms, it represents a potential candidate for addressing the mechanical problems of viscoelastic materials and structures. In this study, functionally graded fractional derivative viscoelastic materials were applied to a fluid-conveying pipe with initial geometric curvature, as common in practical engineering. The effects of the initial geometric defect type, dimensionless delay time, power law exponent, and other parameters on the stability of the fluid-conveying pipe were discussed, providing some theoretical reference for the design of such fluid-conveying pipes. [ABSTRACT FROM AUTHOR]

In this study, the vibration characteristics of a bullet-loaded recorder's vibration damping system under various preload conditions are investigated through theoretical analysis, numerical simulations, and experimental verification. The findings indicate that the inclusion of a polyurethane elastomer vibration damping buffer layer between the cartridge and the recorder, along with the application of a specific preload, significantly reduces the amplitude of vibration acceleration transmitted to the recorder's interior. This, in turn, enhances the overload resistance of the cartridge's internal circuit. Numerical simulation results and theoretical analysis suggest that increasing the preload on the buffer material between the elastomer and the recorder reduces both the frequency ratio and damping ratio of the damping system. This reduction further decreases the amplitude of vibration transmitted to the recorder. However, excessively high preload generates substantial compressive stress within the recorder under static conditions, intensifying during the projectile's accelerated movement. As a consequence, deformation and damage occur to the internal circuitry. Therefore, ensuring that the recorder possesses the structural strength necessary to withstand increased preload is crucial. This balancing act improves the recorder's resistance to shock, vibration, and overload, while also preventing excessive stress-induced damage. [ABSTRACT FROM AUTHOR]

Improving the energy efficiency of robots remains a crucial challenge in soft robotics, with energy harvesting emerging as a promising approach to address it. This study presents a functional soft robotic composite called OPV-DEA, which integrates flexible organic photovoltaic (OPV) and dielectric elastomer actuator (DEA). The composite can simultaneously generate electrostatic bending actuation and harvest energy from external lights. Owing to its simplicity and inherent flexibility, the OPV-DEA is poised to function as a fundamental building block for soft robots. This study aimed to validate this concept by initially establishing the fabrication process of OPV-DEA. Subsequently, experimental samples are fabricated and characterized. The results show that the samples exhibit a voltage-controllable bending actuation of up to 15.6° and harvested power output of 1.35 mW under an incident power irradiance of 11.7 mW/cm2. These performances remain consistent even after 1000 actuation cycles. Finally, to demonstrate the feasibility of soft robotic applications, an untethered swimming robot equipped with two OPV-DEAs is fabricated and tested. The robot demonstrates swimming at a speed of 21.7 mm/s. The power consumption of the robot is dominated by a high-voltage DC-DC converter, with a value approximately 1.5 W. As a result, the on-board OPVs cannot supply the necessary energy during locomotion simultaneously. Instead, they contribute to the overall system by charging a battery used for the controller on board. Nevertheless, these findings suggest that the OPV-DEA could pave the way for the development of an unprecedented range of functional soft robots. [ABSTRACT FROM AUTHOR]

Degradable biomedical elastomers (DBE), characterized by controlled biodegradability, excellent biocompatibility, tailored elasticity, and favorable network design and processability, have become indispensable in tissue repair. This review critically examines the recent advances of biodegradable elastomers for tissue repair, focusing mainly on degradation mechanisms and evaluation, synthesis and crosslinking methods, microstructure design, processing techniques, and tissue repair applications. The review explores the material composition and cross-linking methods of elastomers used in tissue repair, addressing chemistry-related challenges and structural design considerations. In addition, this review focuses on the processing methods of two- and three-dimensional structures of elastomers, and systematically discusses the contribution of processing methods such as solvent casting, electrostatic spinning, and three-/four-dimensional printing of DBE. Furthermore, we describe recent advances in tissue repair using DBE, and include advances achieved in regenerating different tissues, including nerves, tendons, muscle, cardiac, and bone, highlighting their efficacy and versatility. The review concludes by discussing the current challenges in material selection, biodegradation, bioactivation, and manufacturing in tissue repair, and suggests future research directions. This concise yet comprehensive analysis aims to provide valuable insights and technical guidance for advances in DBE for tissue engineering. [ABSTRACT FROM AUTHOR]

Five types of magneto‐rheological elastomers (MREs) based on natural rubber were synthesized by incorporating carbonyl iron particles (CIP) as the primary filler. The objective was to investigate the influence of carbon fiber and magnetic particle content on the mechanical and magneto‐rheological properties of the MREs. Carbon fibers (CF) were further added as secondary reinforcement pre‐modified with polydopamine. The composite's microstructure was examined through scanning electron microscopy (SEM), while the mechanical and magnetodynamic properties were assessed using an electronic universal testing machine and an advanced rotational rheometer. The addition of appropriate amounts of CIP and CF resulted in increased rubber modulus, indicating the formation of a filler‐rubber network and the synergistic effect between carbon fibers as a supporting structure and CIP. Compared to the unfilled MREs, the mechanical and magnetodynamic properties were further improved by adding 2 and 4 wt% CF. These findings demonstrate that employing carbon fibers as reinforcing fillers and incorporating suitable magnetic fillers can enhance the magnetic and mechanical properties of the materials, providing a theoretical basis for the study of MREs' performance. Highlights: CF and CIP synergistically enhance the strength of the rubber matrix.The MR effect is gradually enhanced with the increase of CIP content.Modified CF has a promoting effect on the magnetic responsivity.Magnetic responsivity increases with increasing modified CF content.Improved mechanical and magnetodynamic properties of composites. [ABSTRACT FROM AUTHOR]

Polymer‐based thermal interface materials (TIMs) with excellent thermal conductivity and heat dissipation capabilities play a crucial role in addressing the issue of heat accumulation in advanced integrated electronics. However, establishing improved surface interactions and complete networks to enhance efficient phonon transfer remains a significant challenge. To tackle this problem, surface modification and ice‐templating techniques are commonly employed to create the robust interface crosslinks and continuously thermal conductive pathways. Herein, 2‐mercaptobenzimidazole (MB) was used as a reducing and modifying agent to functionalize graphene oxide (rGO‐MB) within the three‐dimensional networks, which was prepared using a combination of hydrothermal and ice‐templating methods. As a result, the reduced graphene oxide/natural rubber (rGO‐MB/NR) TIMs exhibited a remarkable through‐plane thermal conductivity of 0.93 W m−1 K−1 with a filler loading of 3 wt%. The enhanced interface interactions between rGO‐MB and NR, combined with the establishment of a three‐dimensional network, significantly contributed to the improved thermal conductivity and heat dissipation capabilities. Moreover, the obtained TIMs demonstrated favorable mechanical properties (5.06 MPa, 502%) and excellent insulation performance (3 × 1013 Ω cm). These findings provide the valuable insights into potential solutions for mitigating heat accumulation issues in next‐generation electronics. Highlights: rGO‐MB with thiol groups was obtained by the hydrothermal method.Interactions between rGO‐MB and NR mainly depended on the chemical bonds.rGO‐MB/NR TIMs owned the improved thermal management performance. [ABSTRACT FROM AUTHOR]

EPDM, HNBR and FKM materials were exposed at 150 °C to air under atmospheric pressure and to hydrogen at 50 bar for different ageing times. All measurements after hydrogen exposure were conducted on samples in degassed condition to assess irreversible effects resulting from that exposure and to compare them to those after ageing in air. Density, hardness, tensile properties, compression set, and hydrogen permeability of all samples were analysed. In both ageing environments, HNBR exhibited the most significant changes of material properties. However, for both EPDM and HNBR, considerably less severe ageing effects were observed under hydrogen in comparison to ageing in air. On the other hand, FKM showed about the same low level of deterioration in both ageing environments but exhibited poor resistance against damage due to rapid gas decompression in hydrogen environment that can lead to seal failure. The obtained results may serve as a guidance toward a better understanding for design and utilisation of elastomeric materials in future hydrogen infrastructure components. • Three different rubber seal materials. • Ageing up to 100 days at 150 °C under 50 bar hydrogen or under air. • Comparison of ageing effects after equilibration. • Depending on the material the ageing ranged from less severe to equal to air ageing. • Rapid gas decompression became obvious for fluorocarbon rubber. [ABSTRACT FROM AUTHOR]

Helical structures of liquid crystal elastomers (LCEs) hold promise in soft robotics for self‐regulated rolling motions. The understanding of their motion paths and potentials for terrain exploration remains limited. This study introduces a self‐adjusting, lateral‐rolling soft robot inspired by sidewinder snakes. The spring‐like LCE helical filaments (HFs) autonomously respond to thermal cues, demonstrating dynamic and sustainable locomotion with adaptive rolling along non‐linear paths. By fine‐tuning the diameter, pitch, and modulus of the LCE HFs, and the environmental temperature, the movements of the LCE HFs, allowing for exploration of diverse terrains over a 600 cm2 area within a few minutes, can be programmed. LCE HFs are showcased to navigate through over nine obstacles, including maze escaping, terrain exploration, target hunting, and successfully surmounting staircases through adaptable rolling. [ABSTRACT FROM AUTHOR]