Conductive elastomers combining micromechanical sensitivity,lightweight adaptability,and environmental sustainability are critically needed for advanced flexible electronics requiring precise responsiveness and long-t...Conductive elastomers combining micromechanical sensitivity,lightweight adaptability,and environmental sustainability are critically needed for advanced flexible electronics requiring precise responsiveness and long-term wearability;however,the integration of these properties remains a significant challenge.Here,we present a biomass-derived conductive elastomer featuring a rationally engineered dynamic crosslinked network integrated with a tunable microporous architecture.This structural design imparts pronounced micromechanical sensitivity,an ultralow density(~0.25 g cm^(−3)),and superior mechanical compliance for adaptive deformation.Moreover,the unique micro-spring effect derived from the porous architecture ensures exceptional stretchability(>500%elongation at break)and superior resilience,delivering immediate and stable electrical response under both subtle(<1%)and large(>200%)mechanical stimuli.Intrinsic dynamic interactions endow the elastomer with efficient room temperature self-healing and complete recyclability without compromising performance.First-principles simulations clarify the mechanisms behind micropore formation and the resulting functionality.Beyond its facile and mild fabrication process,this work establishes a scalable route toward high-performance,sustainable conductive elastomers tailored for next-generation soft electronics.展开更多
Laminated elastomeric bearings used in seismic isolation rely on the mechanical properties of their constituent elastomers to ensure effective performance.However,despite their resistance to temperature fluctuations a...Laminated elastomeric bearings used in seismic isolation rely on the mechanical properties of their constituent elastomers to ensure effective performance.However,despite their resistance to temperature fluctuations and environmental aggressors,silicone elastomers exhibit relatively low stiffness,limiting their direct applicability in seismic isolation.This study investigates the effect of fumed silica as a reinforcing filler to enhance the mechanical properties of laminated silicone elastomeric bearings.Elastomeric samples were fabricated with varying fumed silica proportions and subjected to Shore A hardness,uniaxial tensile,and lap shear tests to assess the influence of filler content.Additionally,quasi-static tests were conducted on reduced-scale bearing prototypes under combined vertical compression and cyclic horizontal shear to evaluate their seismic isolation performance.The results demonstrate that fumed silica reinforcement significantly increases stiffness,as evidenced by higher Shore A hardness values.However,a trade-off was observed in tensile properties,with reductions in tensile strength and elongation at break.Despite this,the equivalent elastic modulus did not show substantial variation up to large deformations,indicating that stiffness is preserved under most working conditions.Lap shear tests showed that fumed silica improves shear resistance,while quasi-static tests revealed inelastic behavior with small increases in equivalent shear coefficients but no substantial loss in damping ratios.These findings suggest that fumed silica reinforcement enhances silicone elastomers’stiffness and shear resistance while maintaining moderate damping properties,making it a promising approach for improving the mechanical performance of elastomeric bearings in seismic isolation applications.展开更多
Smart elastomers have attracted great interest due to their excellent adaptability to changing environments and affinity to living organisms,characterized by their ability to undergo programmable deformations or prope...Smart elastomers have attracted great interest due to their excellent adaptability to changing environments and affinity to living organisms,characterized by their ability to undergo programmable deformations or property changes in response to external stimuli(e.g.,heat,light,pH,or electric/magnetic fields).They exhibit huge potential to drive the innovation of soft actuators,robotics,biomedical devices,and wearable electronics.This special issue of Chinese Journal of Polymer Science(CJPS)is dedicated to showcasing cutting-edge advancements in liquid crystal elastomers,hydrogels and the related soft actuators,with a focus on the design,synthesis,characterization,and application of stimuli-responsive soft elastomers and their integration into functional actuation systems.展开更多
Herein,we reported a Tb-carboxyl-imidazole coordination-crosslinked carboxylated nitrile butadiene rubber(XNBR)elastomer design that exhibits high mechanical robustness,fluorochromism,and white-light emission.Imidazol...Herein,we reported a Tb-carboxyl-imidazole coordination-crosslinked carboxylated nitrile butadiene rubber(XNBR)elastomer design that exhibits high mechanical robustness,fluorochromism,and white-light emission.Imidazole(Im),a toughening,sensitizing,and self-emissive ligand,highly intensified the fluorescence emission,remarkably toughened the elastomer,and imparted multistimuli responsiveness to the elastomer.The Tb^(3+)ions acted as cross-linking centers and provided high-temperature sensitivity of fluorescence emission(more sensitive than Eu^(3+)ions).The as-prepared XNBR/Tb/Im elastomer,with excellent puncture resistance,exhibited an ultimate extensibility of about 3100%and the highest tensile strength of 22 MPa.Experimental and theoretical investigations have demonstrated that Tb^(3+)ions are more likely to interact with Im ligands with increasing amounts of Im.The number of coordination cross-links with higher cross-linking functionalities showed an increasing trend during stretching.The elastomer exhibited an excitation wavelength and temperature-dependent green emission.By introducing redemissive Eu^(3+)into the elastomer,a white-light-emitting XNBR/Tb/Eu/Im elastomer with chemo-fluorochromism was fabricated.The XNBR/Tb/Eu/Im elastomer exhibited stable white-light emission during both heating and stretching.Changing the temperature only resulted in a variation in the intensity of the white light.We demonstrated the potential applications of these elastomers in patterning and information anticounterfeiting/encryption.This coordination crosslinked tough elastomer with fluorochromism and white-light emission paves a new way to fabricate soft devices and sensors,where optical information displays and optical signal responses are required.展开更多
Elastomers are widely used in various fields owing to their excellent tensile properties.Recyclable and self-healing properties are key to extending the service life of elastomers.Accumulating evidence indicates that ...Elastomers are widely used in various fields owing to their excellent tensile properties.Recyclable and self-healing properties are key to extending the service life of elastomers.Accumulating evidence indicates that dynamic covalent chemistry has emerged as a powerful tool for constructing recyclable and self-healing materials.In this work,we demonstrate the preparation of a recyclable and self-healable polydimethylsiloxane(PDMS)elastomer based on the Knoevenagel condensation(KC)reaction.This PDMS elastomer was prepared by the KC reaction catalyzed by 4-dimethylaminopyridine(DMAP).The obtained PDMS elastomer exhibited an elongation at break of 266%,a tensile strength of 0.57 MPa,and a good thermal stability(Td=357℃).In addition,because of the presence of dynamic C=C bonds formed by the KC reaction and low glass transition temperature(Tg=-117℃).This PDMS exhibited good self-healing and recycling properties at room temperature and could be reprocessed by hot pressing.In addition,the PDMS elastomer exhibits good application prospects in the fields of adhesives and flexible electronic devices.展开更多
Intrinsic stretchability is a promising attribute of polymer organic solar cells(OSCs).However,rigid molecular blocks typically exhibit poor tensile properties,rendering polymers vulnerable to mechanical stress.In thi...Intrinsic stretchability is a promising attribute of polymer organic solar cells(OSCs).However,rigid molecular blocks typically exhibit poor tensile properties,rendering polymers vulnerable to mechanical stress.In this study,we introduce a different approach utilizing all-small-molecule donors and acceptors to fabricate stretchable OSCs.An elastomer,styrene-b-ethylene-butylene-styrene(SEBS),was embedded to modulate film crystallization and stretchability.SEBS effectively confines the growth process of donors and acceptors,leading to enhancement of the crystallization quality,thus contributing to enhanced device efficiencies.Meanwhile,SEBS can absorb and release mechanical stress during stretching,thereby preventing mechanical degradation of donors and acceptors.The mechanical properties of the OSCs were significantly improved by the incorporation of SEBS.Notably,the crack-onset strain increased from 1.03% to 5.99% with SEBS embedding.These findings present a straightforward strategy for achieving stretchable OSCs using all small molecules,offering a different perspective for realizing stretchable devices.展开更多
Recent experiments have found that a liquid crystal elastomer(LCE)rod supported in the middle can rotate continuously under horizontal illumination due to the combined impacts of gravity and light-fueled lateral bend-...Recent experiments have found that a liquid crystal elastomer(LCE)rod supported in the middle can rotate continuously under horizontal illumination due to the combined impacts of gravity and light-fueled lateral bend-ing deformation.Similar to traditional gravity-driven systems,it is constrained by the direction of gravity and cannot be applied in microgravity environments.This study introduces a lateral constraint to a liquid crystal elastomer rod system,enabling self-rotation under lighting from any direction,including horizontal and vertical illumination.Through theoretical modeling,the results indicate that the system can steadily rotate under the combined impacts of lateral forces and vertical illumination.Factors like thermal energy flux,thermal conduc-tivity coefficient,the LCE rod length,contraction coefficient,and friction coefficient affect the angular velocity of the self-rotation.The numerical computations align closely with the experimental data.Our proposed steadily self-rotating system features a simple structure with constant self-rotation.It operates independently of gravity direction,making it an excellent choice for special environments,such as the microgravity conditions on the Moon.The lateral constraint strategy presented in this study offers a general approach to expanding the applica-tions of gravity-driven self-sustained motion,with promising potential,especially in microgravity settings,where its versatility under varying lighting conditions could yield valuable insights.展开更多
Fibers with deformation-triggered responses are essential for smart textiles and wearable electronics.Here,smart core-shell elastomer fibers with a conductive core and a liquid crystal elastomer shell showing simultan...Fibers with deformation-triggered responses are essential for smart textiles and wearable electronics.Here,smart core-shell elastomer fibers with a conductive core and a liquid crystal elastomer shell showing simultaneous resistance and color responses are designed and prepared.The conductive core is consisted of interconnected liquid metal nanodroplets dispersed in a polymer matrix and the elastomer shell is made of cholesteric liquid crystals.When stretched,the fiber resistance increases as the interconnected pathways of liquid metal nanodroplets along the fiber axis become narrower,and the selective reflection color from the fiber surface blueshifts since the cholesteric pitch decreases.The smart elastomer fibers could be woven into smart textiles and respond to various mechanical deformations,including stretching,bending,compression and twisting.The average resistance change is 51%under 100%strain and its variation is smaller than 4%over 500 cycles,showing remarkable fatigue resistance.The simultaneous resistance and color responses to mechanical deformations make the fibers attractive for broad applications,such as flexible electronics.展开更多
With the rise in environmental awareness,the development of smart polymer materials is gradually becoming environmentally friendly and sustainable.Fluorescent liquid crystal elastomers(LCE)can change their shape or op...With the rise in environmental awareness,the development of smart polymer materials is gradually becoming environmentally friendly and sustainable.Fluorescent liquid crystal elastomers(LCE)can change their shape or optical properties in response to external stimuli,showing great potential for applications in sensing,information storage,and encryption.However,their life cycle is often unsustainable and not in line with the circular economy model.Based on the principle of green chemistry,a fluorescent LCE was developed through the co-polymerization of multiple monomers with 1,2-dithiolane end groups,which exhibited excellent self-healing,reprocessing,and closed-loop recyclability.In addition,by tailoring the phase transition temperature of the LCE,the transparency and fluorescence intensity of the resulting material can change at a low temperature of 8.0℃.By further integrating light or acid/base-triggered fluorescence information,a proof-of-concept for temperature monitoring during short-time vaccine transportation using the reusable fluorescent LCE film is demonstrated.This study establishes a new environmentally friendly manufacturing strategy for multifunctional LCE materials.展开更多
Bio-polyol is considered as a core material to synthesize eco-friendly polyurethane products.However,one of the popular bio-polyols,polytrimethylene ether glycol(PO3G),is reluctant to crystallize and therefore exhibit...Bio-polyol is considered as a core material to synthesize eco-friendly polyurethane products.However,one of the popular bio-polyols,polytrimethylene ether glycol(PO3G),is reluctant to crystallize and therefore exhibits a cold crystallization behavior.This abnormal behavior causes unstable mechanical properties at low-temperature and limits its applications in shape memory devices where crystallization is an essential mechanism.To analyze the unusual phenomenon,we compared different ether polyols focusing on symmetry characteristics and the evenodd effect of carbon backbones.It is found that PO3G has a slow crystallization rate because its ether linkages require specific chain arrangement for attractive interactions.Consequently,a thermal learning mechanism is developed to restore the normal crystallization behavior of elastomers synthesized from the bio-polyol.Repetitive heating and cooling cycles with high-temperature annealing induce urethane exchange reaction and reconstruct the chain orientations for fast crystallization.Results suggest the degree of crystallizations in polyurethane elastomer can be precisely controlled by introducing repetitive thermal treatments to enhance the potential applications of bio-polyols in polymer industries.展开更多
Poly(octamethylene citrate)(POC)is a promising bioelastomer material in the biomedical field.However,its thermosetting nature poses a significant challenge to processing and molding,especially manufacturing the POC-ba...Poly(octamethylene citrate)(POC)is a promising bioelastomer material in the biomedical field.However,its thermosetting nature poses a significant challenge to processing and molding,especially manufacturing the POC-based elastomer particles as potential,degradable and toughened fillers.Firstly,a Pickering emulsion with a pre-polymer(pre-POC)solution in dimethyl carbonate as a dispersed oil phase,a Pullulan(PUL)aqueous solution as a continuous water phase,and chitin nanocrystal(ChiNC)as a particle-type emulsifier was constructed.Secondly,the POC-based core/shell structured microspheres were prepared by spray-drying of the emulsions,and characterized by a scanning electron microscope and a transmission electron microscope.Finally,the POC-based core/shell structured microspheres were used as elastomer fillers to strengthen and toughen a chitosan film,resulting in 26%increase in the tensile strength and 45%increase in the strain at break;the POC-based core/shell structured microsphere as a double-layer drug release system was built in which the hydrophilic drug of tetracycline hydrochloride(TCH)was released from the outer layer and the hydrophobic drug of curcumin was released from the inner layer,roughly following the Ritger-Peppas model.展开更多
Stretchable strain sensors are a crucial component in various applications,such as wearable devices,human-machine interfaces,and soft robotics.Hence,strain sensors with low hysteresis,high fidelity,and accurate sensin...Stretchable strain sensors are a crucial component in various applications,such as wearable devices,human-machine interfaces,and soft robotics.Hence,strain sensors with low hysteresis,high fidelity,and accurate sensing ability are urgently required for the precise measurement of large and high-frequency dynamic deformations.However,the existing hysteresis of the current functional materials utilized in strain sensors significantly impedes the achievement of these properties.Herein,we introduce an ultralow dynamic hysteresis capacitive strain sensor using a low-hysteresis and high-relative-permittivity ionic liquid-elastomer composite as the dielectric material.Based on the low-hysteresis dielectric,the prepared capacitive strain sensors exhibit ultralow electrical hysteresis(2.20%at a strain rate of 100% s^(-1)and strain of100%)and maintain low electrical hysteresis(4.35%)even under extremely high strain rates and large dynamic strain loads(a strain rate of 500% s^(-1)and strain of 100%).Moreover,the strain sensor manifests exceptional cyclic stability under 50,000 cycles of 100%strain at a strain rate of 200% s^(-1);the response curves remain nearly identical throughout these 50,000 cycles.Furthermore,the ultralowhysteresis strain sensor was successfully applied to accurate and reliable real-time human-machine interactions,revealing its great potential in various fields,including electronic skin,flexible robotics,wearable electronics,and virtual reality.展开更多
Conventional liquid crystal elastomer(LCE)-based robots are limited by the need for complex controllers and bulky power supplies,restricting their use in microrobots and soft robots.This paper introduces a novel light...Conventional liquid crystal elastomer(LCE)-based robots are limited by the need for complex controllers and bulky power supplies,restricting their use in microrobots and soft robots.This paper introduces a novel light-powered dicycle that uses an LCE rod,enabling self-rolling by harvesting energy from the environment.The LCE rod serves as the driving force,with energy being supplied by a line light source.Employing a dynamic LCE model,we calculate the transverse curvature of the LCE rod after deformation,as well as the driving moment generated by the shift in a rod’s center of gravity,which allows the dicycle to roll on its own.Through extensive numerical simulations,we identify the correlations between the angular velocity of the dicycle and the key system parameters,specifically the light intensity,LCE rod length,light penetration depth,overall mass of the dicycle,rolling friction coefficient,and wheel radius.Further,the experimental verification is the same as the theoretical result.This proposed light-powered self-rolling dicycle comes with the benefits of the simple structure,the convenient control,the stationary light source,and the small luminous area of the light source.It not only demonstrates self-sustaining oscillations based on active materials,but also highlights the great potential of light-responsive LCE rods in applications such as robotics,aerospace,healthcare,and automation.展开更多
Self-vibrating systems comprised of active materials have great potential for application in the fields of energy harvesting,actuation,bionic instrumentation,and autonomous robotics.However,it is challenging to obtain...Self-vibrating systems comprised of active materials have great potential for application in the fields of energy harvesting,actuation,bionic instrumentation,and autonomous robotics.However,it is challenging to obtain analytical solutions describing these systems,which hinders analysis and design.In this work,we propose a self-vibrating liquid crystal elastomer(LCE)fiber-spring system exposed to spatially-constant gradient light,and determine analytical solutions for its amplitude and period.First,using a dynamic model of LCE,we obtain the equations governing the self-vibration.Then,we analyze two different motion states and elucidate the mechanism of self-vibration.Subsequently,we derive analytical solutions for the amplitude and frequency using the multi-scale method,and compare the solutions with numerical results.The analytical outcomes are shown to be consistent with the numerical calculations,while taking far less computational time.Our findings reveal the utility of the multi-scale method in describing self-vibration,which may contribute to more efficient and accurate analyses of self-vibrating systems.展开更多
In recent years,flexible ionic conductors have made remarkable progress in the fields of energy storage devices and flexible sensors.However,most of these materials still face challenges such as the difficult trade-of...In recent years,flexible ionic conductors have made remarkable progress in the fields of energy storage devices and flexible sensors.However,most of these materials still face challenges such as the difficult trade-off between stretchability and high mechanical strength,as well as insufficient ionic conductivity.Among them,polymerizable deep eutectic solvents(PDES),which possess both hydrogen bond network construction capabilities and ionic conduction properties,have demonstrated great advantages in the synthesis of flexible ionic conductors.Herein,we report an ionic conductive elastomer(ICE)named PCHS-X based on PDES composed of 2-(methacryloyloxy)-N,N,N-trimethylammonium methyl sulfate(MA-MS),choline chloride(ChCl),and 2-hydroxyethyl acrylate(HEA).The introduction of MA-MS enabled the polymer network to form abundant hydrogen bonds,endowing PCHS-X with excellent mechanical strength,high transparency,favorable ionic conductivity,self-adhesiveness,and self-healing efficiency.When used as a strain sensor,the PCHS-X exhibits highly sensitive strain response,along with good stability and durability,allowing it to accurately monitor the movement of human body parts such as fingers,wrists,elbows,and knees.Additionally,owing to the enhanced ionic mobility at higher temperatures,this material also possesses excellent temperature sensing performance,enabling the fabrication of simple temperature sensors that can sensitively respond to temperature changes.This research provides new strategies for the practical applications of flexible electronic devices in fields such as wearable health monitoring and intelligent human-machine interaction.展开更多
Soft underwater swimming robots driven by smart materials show unique advantages in ocean exploration,such as low noise,high flexibility and good environmental interaction ability.The dielectric elastomer(DE),as a new...Soft underwater swimming robots driven by smart materials show unique advantages in ocean exploration,such as low noise,high flexibility and good environmental interaction ability.The dielectric elastomer(DE),as a new kind of soft intelligent material,has the characteristics of a low elastic modulus,large deformation range,high energy density and fast response speed.DE actuator(DEA)drive systems use the deformation characteristics of dielectric materials to drive the mechanical system,which has become a research hotspot in the field of soft robots.In this paper,a tubular actuator based on DEs is designed and its performance is studied.Firstly,the structure and driving process of a DEA are described,and a tubular DEA is designed.Studying the elongation ratio of the DEA pre-stretching shows that when the axial elongation ratio is 3 times and the circumferential elongation ratio is 4 times,the maximum deformation effect can be obtained under voltage excitation.At a voltage of 6.0 k V,a single pipe section DEA achieves a bending angle of 25.9°and a driving force of 73.8 m N.Secondly,the effect of the DEA series on the bending angle and response characteristics is studied.The experimental results show that the maximum bending angle of the three joint actuators in series can reach 59.3°under6.0 k V voltage,which significantly improves the overall bending performance.In addition,the truncation frequency of the drive module after the series is increased to 0.62 Hz,showing better frequency response capability.The excellent performance of the pipe joint actuator in its bending angle,response characteristic and driving force is verified.展开更多
The development of high-performance functional composites has become a research hotspot in response to the hazards of over-heating and electromagnetic radiation in modern electronic devices.Herein,we grew magnetic Fe_...The development of high-performance functional composites has become a research hotspot in response to the hazards of over-heating and electromagnetic radiation in modern electronic devices.Herein,we grew magnetic Fe_(3)O_(4)particles in situ on the MXene layer to obtain an MXene@Fe_(3)O_(4)composite with rich heterogeneous interfaces.Owing to the unique heterostructure and the synergistic effects of multiple electromagnetic wave absorption mechanisms,the composite achieved a minimum reflection loss of-27.14 dB and an effect-ive absorption bandwidth of 2.05 GHz at an absorption thickness of 2 mm.Moreover,the MXene@Fe_(3)O_(4)composite could be encapsu-lated in thermoplastic polyurethane(TPU)via thermal curing.The obtained composite elastomer exhibited a strong tensile strength,and its thermal diffusivity was 113%higher than that of pure TPU.Such additional mechanical properties and thermal conduction features render this composite elastomer an advanced electromagnetic absorber to adapt to the ever-changing environment for expanding practical applications.展开更多
Liquid crystal elastomers(LCEs)exhibit exceptional reversible deformation and unique physical properties owing to their order-disorder phase transition under external stimuli.Among these deformations,helical structure...Liquid crystal elastomers(LCEs)exhibit exceptional reversible deformation and unique physical properties owing to their order-disorder phase transition under external stimuli.Among these deformations,helical structures have attracted attention owing to their distinctive configurations and promising applications in biomimetics and microelectronics.However,the helical deformation behavior of fiber actuators is critically influenced by their morphologies and alignments;yet,the underlying mechanisms are not fully understood.Through a two-step azaMichael addition reaction and direct ink writing(DIW)4D printing technology,fiber-based LCE actuators with a core-sheath alignment structure were fabricated and exhibited reversible helical deformation upon heating.By adjusting the printing parameters,the filament number,width,thickness,and core-sheath structure of the fiber actuators can be precisely controlled,resulting in deformation behaviors,such as contraction,bending,and helical twisting.Finite element simulations were performed to investigate the deformation behaviors of the fiber actuators,providing insights into the variations in stress and strain during the shape-changing process,which can be used to explain the shape-morphing mechanism.These findings demonstrate that the precise tuning of printing parameters enables the controllable construction of LCE actuator morphology and customization of their functional properties,paving the way for advanced applications in smart fabrics,biomedical engineering,and flexible electronics.展开更多
Liquid crystal elastomers(LCEs)are advanced materials characterized by their rubber-like hyperelasticity and liquid crystal phase transitions,offering exceptional mechanical properties.The development of smart mechani...Liquid crystal elastomers(LCEs)are advanced materials characterized by their rubber-like hyperelasticity and liquid crystal phase transitions,offering exceptional mechanical properties.The development of smart mechanical metamaterials(SMMs)from LCEs expands the potential for controlling mechanical responses and achieving nonlinear behaviors not possible with traditional metamaterials.However,the challenge lies in managing the interplay between nonlinear material responses and structural complexity,making the inverse design of LCE-based SMMs exceptionally demanding.In this paper,we introduce a design framework for LCE smart mechanical metamaterials that leverages neural networks and evolution strategies(ES)to optimize designs with nonlinear mechanical responses.Our approach involves constructing a flexible,unit-cell-based metamaterial model that integrates the soft elastic behavior and thermo-mechanical coupling of LCEs.The combination of microscopic liquid crystal molecule rotation and macroscopic block rotation enables highly tunable and nonlinear mechanical behaviors,of which the precise inverse design of stress-stretch responses is obtained via neural networks combined with ES.In addition,stimuli responses in the liquid crystal elastomers enable real-time adaptability and achieve tailored stress plateaus that are not possible with traditional metamaterials.Our findings provide new pathways in the design and optimization of advanced materials in flexible electronic devices,intelligent actuators,and systems for energy absorption and dissipation.展开更多
Integrated conductive elastomers with excellent mechanical performance,stable high conductivity,self-healing capabilities,and high transparency are critical for advancing wearable devices.Nevertheless,achieving an opt...Integrated conductive elastomers with excellent mechanical performance,stable high conductivity,self-healing capabilities,and high transparency are critical for advancing wearable devices.Nevertheless,achieving an optimal balance among these properties remains a significant challenge.Herein,through in situ free-radical copolymerization of 2-[2-(2-methoxyethoxy)ethoxy]ethyl acrylate(TEEA)and vinylimidazole(VI)in the presence of polyethylene glycol(PEG;Mn=400),tough P(TEEA-co-VI)/PEG elastomers with multiple functionalities were prepared,in which P(TEEA-co-VI)was dynamically cross-linked by imidazole-Zn^(2+)metal coordination crosslinks,and physically blended with PEG as polymer electrolyte to form a homogeneous mixture.Notably,Zn^(2+)has a negligible impact on the polymerization process,allowing for the in situ formation of numerous imidazole-Zn^(2+)metal coordination crosslinks,which can effectively dissipate energy upon stretching to largely reinforce the elastomers.The obtained P(TEEA-co-VI)/PEG elastomers exhibited a high toughness of 10.0 MJ·m^(-3) with a high tensile strength of 3.3 MPa and a large elongation at break of 645%,along with outstanding self-healing capabilities due to the dynamic coordination crosslinks.Moreover,because of the miscibility of PEG with PTEEA copolymer matrix,and Li+can form weak coordination interactions with the ethoxy(EO)units in PEG and PTEEA,acting as a bridge to integrate PEG into the elastomer network.The resulted P(TEEA-co-VI)/PEG elastomers showed high transparency(92%)and stable high conductivity of 1.09×10_(-4) S·cm^(-1).In summary,the obtained elastomers exhibited a well-balanced combination of high toughness,high ionic conductivity,excellent self-healing capabilities,and high transparency,making them promising for applications in flexible strain sensors.展开更多
基金supported by National Natural Science Foundation of China(No.52103044)Double First-Class Initiative University of Science and Technology of China(KY2400000037)the Young Talent Programme(GG2400007009).
文摘Conductive elastomers combining micromechanical sensitivity,lightweight adaptability,and environmental sustainability are critically needed for advanced flexible electronics requiring precise responsiveness and long-term wearability;however,the integration of these properties remains a significant challenge.Here,we present a biomass-derived conductive elastomer featuring a rationally engineered dynamic crosslinked network integrated with a tunable microporous architecture.This structural design imparts pronounced micromechanical sensitivity,an ultralow density(~0.25 g cm^(−3)),and superior mechanical compliance for adaptive deformation.Moreover,the unique micro-spring effect derived from the porous architecture ensures exceptional stretchability(>500%elongation at break)and superior resilience,delivering immediate and stable electrical response under both subtle(<1%)and large(>200%)mechanical stimuli.Intrinsic dynamic interactions endow the elastomer with efficient room temperature self-healing and complete recyclability without compromising performance.First-principles simulations clarify the mechanisms behind micropore formation and the resulting functionality.Beyond its facile and mild fabrication process,this work establishes a scalable route toward high-performance,sustainable conductive elastomers tailored for next-generation soft electronics.
文摘Laminated elastomeric bearings used in seismic isolation rely on the mechanical properties of their constituent elastomers to ensure effective performance.However,despite their resistance to temperature fluctuations and environmental aggressors,silicone elastomers exhibit relatively low stiffness,limiting their direct applicability in seismic isolation.This study investigates the effect of fumed silica as a reinforcing filler to enhance the mechanical properties of laminated silicone elastomeric bearings.Elastomeric samples were fabricated with varying fumed silica proportions and subjected to Shore A hardness,uniaxial tensile,and lap shear tests to assess the influence of filler content.Additionally,quasi-static tests were conducted on reduced-scale bearing prototypes under combined vertical compression and cyclic horizontal shear to evaluate their seismic isolation performance.The results demonstrate that fumed silica reinforcement significantly increases stiffness,as evidenced by higher Shore A hardness values.However,a trade-off was observed in tensile properties,with reductions in tensile strength and elongation at break.Despite this,the equivalent elastic modulus did not show substantial variation up to large deformations,indicating that stiffness is preserved under most working conditions.Lap shear tests showed that fumed silica improves shear resistance,while quasi-static tests revealed inelastic behavior with small increases in equivalent shear coefficients but no substantial loss in damping ratios.These findings suggest that fumed silica reinforcement enhances silicone elastomers’stiffness and shear resistance while maintaining moderate damping properties,making it a promising approach for improving the mechanical performance of elastomeric bearings in seismic isolation applications.
文摘Smart elastomers have attracted great interest due to their excellent adaptability to changing environments and affinity to living organisms,characterized by their ability to undergo programmable deformations or property changes in response to external stimuli(e.g.,heat,light,pH,or electric/magnetic fields).They exhibit huge potential to drive the innovation of soft actuators,robotics,biomedical devices,and wearable electronics.This special issue of Chinese Journal of Polymer Science(CJPS)is dedicated to showcasing cutting-edge advancements in liquid crystal elastomers,hydrogels and the related soft actuators,with a focus on the design,synthesis,characterization,and application of stimuli-responsive soft elastomers and their integration into functional actuation systems.
基金financially supported by the National Natural Science Foundation of China(Nos.22175100 and 52173020)the Natural Science Foundation of Zhejiang Province(No.LY22E030001)the Natural Science Foundation of Ningbo(No.2022J102)。
文摘Herein,we reported a Tb-carboxyl-imidazole coordination-crosslinked carboxylated nitrile butadiene rubber(XNBR)elastomer design that exhibits high mechanical robustness,fluorochromism,and white-light emission.Imidazole(Im),a toughening,sensitizing,and self-emissive ligand,highly intensified the fluorescence emission,remarkably toughened the elastomer,and imparted multistimuli responsiveness to the elastomer.The Tb^(3+)ions acted as cross-linking centers and provided high-temperature sensitivity of fluorescence emission(more sensitive than Eu^(3+)ions).The as-prepared XNBR/Tb/Im elastomer,with excellent puncture resistance,exhibited an ultimate extensibility of about 3100%and the highest tensile strength of 22 MPa.Experimental and theoretical investigations have demonstrated that Tb^(3+)ions are more likely to interact with Im ligands with increasing amounts of Im.The number of coordination cross-links with higher cross-linking functionalities showed an increasing trend during stretching.The elastomer exhibited an excitation wavelength and temperature-dependent green emission.By introducing redemissive Eu^(3+)into the elastomer,a white-light-emitting XNBR/Tb/Eu/Im elastomer with chemo-fluorochromism was fabricated.The XNBR/Tb/Eu/Im elastomer exhibited stable white-light emission during both heating and stretching.Changing the temperature only resulted in a variation in the intensity of the white light.We demonstrated the potential applications of these elastomers in patterning and information anticounterfeiting/encryption.This coordination crosslinked tough elastomer with fluorochromism and white-light emission paves a new way to fabricate soft devices and sensors,where optical information displays and optical signal responses are required.
基金supported by the National Natural Science Foundation of China(Nos.51973025 and 52222307)Jilin Science and Technology Bureau(Nos.20220204107YY and 20230204086YY)+1 种基金Changchun Science and Technology Bureau(No.21ZGY06)Jilin Province Development and Reform Commission(No.2023C028-4).
文摘Elastomers are widely used in various fields owing to their excellent tensile properties.Recyclable and self-healing properties are key to extending the service life of elastomers.Accumulating evidence indicates that dynamic covalent chemistry has emerged as a powerful tool for constructing recyclable and self-healing materials.In this work,we demonstrate the preparation of a recyclable and self-healable polydimethylsiloxane(PDMS)elastomer based on the Knoevenagel condensation(KC)reaction.This PDMS elastomer was prepared by the KC reaction catalyzed by 4-dimethylaminopyridine(DMAP).The obtained PDMS elastomer exhibited an elongation at break of 266%,a tensile strength of 0.57 MPa,and a good thermal stability(Td=357℃).In addition,because of the presence of dynamic C=C bonds formed by the KC reaction and low glass transition temperature(Tg=-117℃).This PDMS exhibited good self-healing and recycling properties at room temperature and could be reprocessed by hot pressing.In addition,the PDMS elastomer exhibits good application prospects in the fields of adhesives and flexible electronic devices.
基金financially supported by the National Natural Science Foundation of China(Nos.52303239 and 51933001)Natural Science Foundation of Shandong Province(Nos.ZR2022QB141 and 2023HWYQ-087).
文摘Intrinsic stretchability is a promising attribute of polymer organic solar cells(OSCs).However,rigid molecular blocks typically exhibit poor tensile properties,rendering polymers vulnerable to mechanical stress.In this study,we introduce a different approach utilizing all-small-molecule donors and acceptors to fabricate stretchable OSCs.An elastomer,styrene-b-ethylene-butylene-styrene(SEBS),was embedded to modulate film crystallization and stretchability.SEBS effectively confines the growth process of donors and acceptors,leading to enhancement of the crystallization quality,thus contributing to enhanced device efficiencies.Meanwhile,SEBS can absorb and release mechanical stress during stretching,thereby preventing mechanical degradation of donors and acceptors.The mechanical properties of the OSCs were significantly improved by the incorporation of SEBS.Notably,the crack-onset strain increased from 1.03% to 5.99% with SEBS embedding.These findings present a straightforward strategy for achieving stretchable OSCs using all small molecules,offering a different perspective for realizing stretchable devices.
基金supported by the University Natural Science Research Project of Anhui Province(Grant Nos.2022AH040042 and 2022AH020029)the National Natural Science Foundation of China(Grant No.12172001)+1 种基金Anhui Provincial Natural Science Foundation(Grant No.2208085Y01)the Housing and Urban-Rural Development Science and Technology Project of Anhui Province(Grant No.2022-YF069).
文摘Recent experiments have found that a liquid crystal elastomer(LCE)rod supported in the middle can rotate continuously under horizontal illumination due to the combined impacts of gravity and light-fueled lateral bend-ing deformation.Similar to traditional gravity-driven systems,it is constrained by the direction of gravity and cannot be applied in microgravity environments.This study introduces a lateral constraint to a liquid crystal elastomer rod system,enabling self-rotation under lighting from any direction,including horizontal and vertical illumination.Through theoretical modeling,the results indicate that the system can steadily rotate under the combined impacts of lateral forces and vertical illumination.Factors like thermal energy flux,thermal conduc-tivity coefficient,the LCE rod length,contraction coefficient,and friction coefficient affect the angular velocity of the self-rotation.The numerical computations align closely with the experimental data.Our proposed steadily self-rotating system features a simple structure with constant self-rotation.It operates independently of gravity direction,making it an excellent choice for special environments,such as the microgravity conditions on the Moon.The lateral constraint strategy presented in this study offers a general approach to expanding the applica-tions of gravity-driven self-sustained motion,with promising potential,especially in microgravity settings,where its versatility under varying lighting conditions could yield valuable insights.
基金supported by the National Natural Science Foundation of China(No.22278352)National Key Research and Development Program of China(No.2021YFC3001100)。
文摘Fibers with deformation-triggered responses are essential for smart textiles and wearable electronics.Here,smart core-shell elastomer fibers with a conductive core and a liquid crystal elastomer shell showing simultaneous resistance and color responses are designed and prepared.The conductive core is consisted of interconnected liquid metal nanodroplets dispersed in a polymer matrix and the elastomer shell is made of cholesteric liquid crystals.When stretched,the fiber resistance increases as the interconnected pathways of liquid metal nanodroplets along the fiber axis become narrower,and the selective reflection color from the fiber surface blueshifts since the cholesteric pitch decreases.The smart elastomer fibers could be woven into smart textiles and respond to various mechanical deformations,including stretching,bending,compression and twisting.The average resistance change is 51%under 100%strain and its variation is smaller than 4%over 500 cycles,showing remarkable fatigue resistance.The simultaneous resistance and color responses to mechanical deformations make the fibers attractive for broad applications,such as flexible electronics.
基金support from the National Natural Science Foundation of China(Nos.52073017 and 51773009)。
文摘With the rise in environmental awareness,the development of smart polymer materials is gradually becoming environmentally friendly and sustainable.Fluorescent liquid crystal elastomers(LCE)can change their shape or optical properties in response to external stimuli,showing great potential for applications in sensing,information storage,and encryption.However,their life cycle is often unsustainable and not in line with the circular economy model.Based on the principle of green chemistry,a fluorescent LCE was developed through the co-polymerization of multiple monomers with 1,2-dithiolane end groups,which exhibited excellent self-healing,reprocessing,and closed-loop recyclability.In addition,by tailoring the phase transition temperature of the LCE,the transparency and fluorescence intensity of the resulting material can change at a low temperature of 8.0℃.By further integrating light or acid/base-triggered fluorescence information,a proof-of-concept for temperature monitoring during short-time vaccine transportation using the reusable fluorescent LCE film is demonstrated.This study establishes a new environmentally friendly manufacturing strategy for multifunctional LCE materials.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(RS-2024-00451587)supported by Post-plastic Specialized Graduate Program through the Korea Environmental Industry&Technology Institute(KEITI)funded by the Ministry of Environment(MOE).
文摘Bio-polyol is considered as a core material to synthesize eco-friendly polyurethane products.However,one of the popular bio-polyols,polytrimethylene ether glycol(PO3G),is reluctant to crystallize and therefore exhibits a cold crystallization behavior.This abnormal behavior causes unstable mechanical properties at low-temperature and limits its applications in shape memory devices where crystallization is an essential mechanism.To analyze the unusual phenomenon,we compared different ether polyols focusing on symmetry characteristics and the evenodd effect of carbon backbones.It is found that PO3G has a slow crystallization rate because its ether linkages require specific chain arrangement for attractive interactions.Consequently,a thermal learning mechanism is developed to restore the normal crystallization behavior of elastomers synthesized from the bio-polyol.Repetitive heating and cooling cycles with high-temperature annealing induce urethane exchange reaction and reconstruct the chain orientations for fast crystallization.Results suggest the degree of crystallizations in polyurethane elastomer can be precisely controlled by introducing repetitive thermal treatments to enhance the potential applications of bio-polyols in polymer industries.
文摘Poly(octamethylene citrate)(POC)is a promising bioelastomer material in the biomedical field.However,its thermosetting nature poses a significant challenge to processing and molding,especially manufacturing the POC-based elastomer particles as potential,degradable and toughened fillers.Firstly,a Pickering emulsion with a pre-polymer(pre-POC)solution in dimethyl carbonate as a dispersed oil phase,a Pullulan(PUL)aqueous solution as a continuous water phase,and chitin nanocrystal(ChiNC)as a particle-type emulsifier was constructed.Secondly,the POC-based core/shell structured microspheres were prepared by spray-drying of the emulsions,and characterized by a scanning electron microscope and a transmission electron microscope.Finally,the POC-based core/shell structured microspheres were used as elastomer fillers to strengthen and toughen a chitosan film,resulting in 26%increase in the tensile strength and 45%increase in the strain at break;the POC-based core/shell structured microsphere as a double-layer drug release system was built in which the hydrophilic drug of tetracycline hydrochloride(TCH)was released from the outer layer and the hydrophobic drug of curcumin was released from the inner layer,roughly following the Ritger-Peppas model.
基金financially supported by the National Natural Science Foundation of China(Nos.52250398,52125205 and U20A20166)the Natural Science Foundation of Beijing Municipality(No.2222088)+1 种基金Shenzhen Science and Technology Program(No.KQTD20170810105439418)the Fundamental Research Funds for the Central Universities
文摘Stretchable strain sensors are a crucial component in various applications,such as wearable devices,human-machine interfaces,and soft robotics.Hence,strain sensors with low hysteresis,high fidelity,and accurate sensing ability are urgently required for the precise measurement of large and high-frequency dynamic deformations.However,the existing hysteresis of the current functional materials utilized in strain sensors significantly impedes the achievement of these properties.Herein,we introduce an ultralow dynamic hysteresis capacitive strain sensor using a low-hysteresis and high-relative-permittivity ionic liquid-elastomer composite as the dielectric material.Based on the low-hysteresis dielectric,the prepared capacitive strain sensors exhibit ultralow electrical hysteresis(2.20%at a strain rate of 100% s^(-1)and strain of100%)and maintain low electrical hysteresis(4.35%)even under extremely high strain rates and large dynamic strain loads(a strain rate of 500% s^(-1)and strain of 100%).Moreover,the strain sensor manifests exceptional cyclic stability under 50,000 cycles of 100%strain at a strain rate of 200% s^(-1);the response curves remain nearly identical throughout these 50,000 cycles.Furthermore,the ultralowhysteresis strain sensor was successfully applied to accurate and reliable real-time human-machine interactions,revealing its great potential in various fields,including electronic skin,flexible robotics,wearable electronics,and virtual reality.
基金supported by the National Natural Science Foundation of China(No.12172001)the University Natural Science Research Project of Anhui Province of China(No.2022AH020029)+1 种基金the Anhui Provincial Natural Science Foundation(Nos.2208085Y01 and 2008085QA23)the Housing and Urban-Rural Development Science and Technology Project of Anhui Province of China(No.2023-YF129)。
文摘Conventional liquid crystal elastomer(LCE)-based robots are limited by the need for complex controllers and bulky power supplies,restricting their use in microrobots and soft robots.This paper introduces a novel light-powered dicycle that uses an LCE rod,enabling self-rolling by harvesting energy from the environment.The LCE rod serves as the driving force,with energy being supplied by a line light source.Employing a dynamic LCE model,we calculate the transverse curvature of the LCE rod after deformation,as well as the driving moment generated by the shift in a rod’s center of gravity,which allows the dicycle to roll on its own.Through extensive numerical simulations,we identify the correlations between the angular velocity of the dicycle and the key system parameters,specifically the light intensity,LCE rod length,light penetration depth,overall mass of the dicycle,rolling friction coefficient,and wheel radius.Further,the experimental verification is the same as the theoretical result.This proposed light-powered self-rolling dicycle comes with the benefits of the simple structure,the convenient control,the stationary light source,and the small luminous area of the light source.It not only demonstrates self-sustaining oscillations based on active materials,but also highlights the great potential of light-responsive LCE rods in applications such as robotics,aerospace,healthcare,and automation.
基金supported by the National Natural Science Foundation of China(No.12172001)the University Natural Science Research Project of Anhui Province(No.2022AH020029)+1 种基金the Anhui Provincial Natural Science Foundation(Nos.2208085Y01 and 2008085QA23)the Housing and Urban-Rural Development Science and Technology Project of Anhui Province(No.2023-YF129),China.
文摘Self-vibrating systems comprised of active materials have great potential for application in the fields of energy harvesting,actuation,bionic instrumentation,and autonomous robotics.However,it is challenging to obtain analytical solutions describing these systems,which hinders analysis and design.In this work,we propose a self-vibrating liquid crystal elastomer(LCE)fiber-spring system exposed to spatially-constant gradient light,and determine analytical solutions for its amplitude and period.First,using a dynamic model of LCE,we obtain the equations governing the self-vibration.Then,we analyze two different motion states and elucidate the mechanism of self-vibration.Subsequently,we derive analytical solutions for the amplitude and frequency using the multi-scale method,and compare the solutions with numerical results.The analytical outcomes are shown to be consistent with the numerical calculations,while taking far less computational time.Our findings reveal the utility of the multi-scale method in describing self-vibration,which may contribute to more efficient and accurate analyses of self-vibrating systems.
基金financially supported by the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.20KJA150009)a Project Funded by the Priority Academic Program Development(PAPD)of Jiangsu Higher Education Institutions。
文摘In recent years,flexible ionic conductors have made remarkable progress in the fields of energy storage devices and flexible sensors.However,most of these materials still face challenges such as the difficult trade-off between stretchability and high mechanical strength,as well as insufficient ionic conductivity.Among them,polymerizable deep eutectic solvents(PDES),which possess both hydrogen bond network construction capabilities and ionic conduction properties,have demonstrated great advantages in the synthesis of flexible ionic conductors.Herein,we report an ionic conductive elastomer(ICE)named PCHS-X based on PDES composed of 2-(methacryloyloxy)-N,N,N-trimethylammonium methyl sulfate(MA-MS),choline chloride(ChCl),and 2-hydroxyethyl acrylate(HEA).The introduction of MA-MS enabled the polymer network to form abundant hydrogen bonds,endowing PCHS-X with excellent mechanical strength,high transparency,favorable ionic conductivity,self-adhesiveness,and self-healing efficiency.When used as a strain sensor,the PCHS-X exhibits highly sensitive strain response,along with good stability and durability,allowing it to accurately monitor the movement of human body parts such as fingers,wrists,elbows,and knees.Additionally,owing to the enhanced ionic mobility at higher temperatures,this material also possesses excellent temperature sensing performance,enabling the fabrication of simple temperature sensors that can sensitively respond to temperature changes.This research provides new strategies for the practical applications of flexible electronic devices in fields such as wearable health monitoring and intelligent human-machine interaction.
基金Project supported by the Science and Technology Research Project of Henan Province in China(Grant No.222102220022)。
文摘Soft underwater swimming robots driven by smart materials show unique advantages in ocean exploration,such as low noise,high flexibility and good environmental interaction ability.The dielectric elastomer(DE),as a new kind of soft intelligent material,has the characteristics of a low elastic modulus,large deformation range,high energy density and fast response speed.DE actuator(DEA)drive systems use the deformation characteristics of dielectric materials to drive the mechanical system,which has become a research hotspot in the field of soft robots.In this paper,a tubular actuator based on DEs is designed and its performance is studied.Firstly,the structure and driving process of a DEA are described,and a tubular DEA is designed.Studying the elongation ratio of the DEA pre-stretching shows that when the axial elongation ratio is 3 times and the circumferential elongation ratio is 4 times,the maximum deformation effect can be obtained under voltage excitation.At a voltage of 6.0 k V,a single pipe section DEA achieves a bending angle of 25.9°and a driving force of 73.8 m N.Secondly,the effect of the DEA series on the bending angle and response characteristics is studied.The experimental results show that the maximum bending angle of the three joint actuators in series can reach 59.3°under6.0 k V voltage,which significantly improves the overall bending performance.In addition,the truncation frequency of the drive module after the series is increased to 0.62 Hz,showing better frequency response capability.The excellent performance of the pipe joint actuator in its bending angle,response characteristic and driving force is verified.
基金supported by the Zhejiang Provincial Natural Science Foundation of China(No.LQ22E030016)the National Natural Science Foundation of China(No.52275137)+1 种基金the China Postdoctoral Science Foundation(No.2022M722831)the Postdoctoral Research Selected Funding Project of Zhejiang Province,China(No.ZJ2022063).
文摘The development of high-performance functional composites has become a research hotspot in response to the hazards of over-heating and electromagnetic radiation in modern electronic devices.Herein,we grew magnetic Fe_(3)O_(4)particles in situ on the MXene layer to obtain an MXene@Fe_(3)O_(4)composite with rich heterogeneous interfaces.Owing to the unique heterostructure and the synergistic effects of multiple electromagnetic wave absorption mechanisms,the composite achieved a minimum reflection loss of-27.14 dB and an effect-ive absorption bandwidth of 2.05 GHz at an absorption thickness of 2 mm.Moreover,the MXene@Fe_(3)O_(4)composite could be encapsu-lated in thermoplastic polyurethane(TPU)via thermal curing.The obtained composite elastomer exhibited a strong tensile strength,and its thermal diffusivity was 113%higher than that of pure TPU.Such additional mechanical properties and thermal conduction features render this composite elastomer an advanced electromagnetic absorber to adapt to the ever-changing environment for expanding practical applications.
基金financially supported by the National Natural Science Foundation of China(Nos.52103145 and 11832007)Science&Technology Department of Sichuan Province(No.2025ZNSFSC0352)State Key Laboratory of Polymer Materials Engineering(No.sklpme-2024-1-03)。
文摘Liquid crystal elastomers(LCEs)exhibit exceptional reversible deformation and unique physical properties owing to their order-disorder phase transition under external stimuli.Among these deformations,helical structures have attracted attention owing to their distinctive configurations and promising applications in biomimetics and microelectronics.However,the helical deformation behavior of fiber actuators is critically influenced by their morphologies and alignments;yet,the underlying mechanisms are not fully understood.Through a two-step azaMichael addition reaction and direct ink writing(DIW)4D printing technology,fiber-based LCE actuators with a core-sheath alignment structure were fabricated and exhibited reversible helical deformation upon heating.By adjusting the printing parameters,the filament number,width,thickness,and core-sheath structure of the fiber actuators can be precisely controlled,resulting in deformation behaviors,such as contraction,bending,and helical twisting.Finite element simulations were performed to investigate the deformation behaviors of the fiber actuators,providing insights into the variations in stress and strain during the shape-changing process,which can be used to explain the shape-morphing mechanism.These findings demonstrate that the precise tuning of printing parameters enables the controllable construction of LCE actuator morphology and customization of their functional properties,paving the way for advanced applications in smart fabrics,biomedical engineering,and flexible electronics.
基金supported by the National Natural Science Foundation of China(Grant Nos.12322207,12202120 and T2293720/T2293722)the Shenzhen Science and Technology Program,China(Grant No.JCYJ20220531095210022)+1 种基金the Fundamental Research Funds for the Central Universities(Grant No.HIT.OCEF.2022037)financial support by the National Key Research and Development Program of China(Grant No.2023YFB3812500)。
文摘Liquid crystal elastomers(LCEs)are advanced materials characterized by their rubber-like hyperelasticity and liquid crystal phase transitions,offering exceptional mechanical properties.The development of smart mechanical metamaterials(SMMs)from LCEs expands the potential for controlling mechanical responses and achieving nonlinear behaviors not possible with traditional metamaterials.However,the challenge lies in managing the interplay between nonlinear material responses and structural complexity,making the inverse design of LCE-based SMMs exceptionally demanding.In this paper,we introduce a design framework for LCE smart mechanical metamaterials that leverages neural networks and evolution strategies(ES)to optimize designs with nonlinear mechanical responses.Our approach involves constructing a flexible,unit-cell-based metamaterial model that integrates the soft elastic behavior and thermo-mechanical coupling of LCEs.The combination of microscopic liquid crystal molecule rotation and macroscopic block rotation enables highly tunable and nonlinear mechanical behaviors,of which the precise inverse design of stress-stretch responses is obtained via neural networks combined with ES.In addition,stimuli responses in the liquid crystal elastomers enable real-time adaptability and achieve tailored stress plateaus that are not possible with traditional metamaterials.Our findings provide new pathways in the design and optimization of advanced materials in flexible electronic devices,intelligent actuators,and systems for energy absorption and dissipation.
基金supported by the National Natural Science Foundation of China(Nos.52273023,51973103,and 21774069).
文摘Integrated conductive elastomers with excellent mechanical performance,stable high conductivity,self-healing capabilities,and high transparency are critical for advancing wearable devices.Nevertheless,achieving an optimal balance among these properties remains a significant challenge.Herein,through in situ free-radical copolymerization of 2-[2-(2-methoxyethoxy)ethoxy]ethyl acrylate(TEEA)and vinylimidazole(VI)in the presence of polyethylene glycol(PEG;Mn=400),tough P(TEEA-co-VI)/PEG elastomers with multiple functionalities were prepared,in which P(TEEA-co-VI)was dynamically cross-linked by imidazole-Zn^(2+)metal coordination crosslinks,and physically blended with PEG as polymer electrolyte to form a homogeneous mixture.Notably,Zn^(2+)has a negligible impact on the polymerization process,allowing for the in situ formation of numerous imidazole-Zn^(2+)metal coordination crosslinks,which can effectively dissipate energy upon stretching to largely reinforce the elastomers.The obtained P(TEEA-co-VI)/PEG elastomers exhibited a high toughness of 10.0 MJ·m^(-3) with a high tensile strength of 3.3 MPa and a large elongation at break of 645%,along with outstanding self-healing capabilities due to the dynamic coordination crosslinks.Moreover,because of the miscibility of PEG with PTEEA copolymer matrix,and Li+can form weak coordination interactions with the ethoxy(EO)units in PEG and PTEEA,acting as a bridge to integrate PEG into the elastomer network.The resulted P(TEEA-co-VI)/PEG elastomers showed high transparency(92%)and stable high conductivity of 1.09×10_(-4) S·cm^(-1).In summary,the obtained elastomers exhibited a well-balanced combination of high toughness,high ionic conductivity,excellent self-healing capabilities,and high transparency,making them promising for applications in flexible strain sensors.
