Three-dimensional(3 D)printing has revolutionized the design and production of customized scaffolds,but the minimally invasive implantation of 3 D-printed structures into the human body remains challenging.This has pr...Three-dimensional(3 D)printing has revolutionized the design and production of customized scaffolds,but the minimally invasive implantation of 3 D-printed structures into the human body remains challenging.This has prompted the exploration of innovative materials and technical solutions.Shape-memory polymers,as advanced intelligent materials,exhibit considerable potential in minimally invasive surgical applications.Herein,we developed a novel thermosetting shape-memory polymer,poly(L-lactic acid)-trimethylene carbonate-glycolic acid(PLLA-TMC-GA),for the fabrication of bioengineered scaffolds with body temperature-activated shape-memory functionality.We comprehensively evaluated the mechanical properties,thermal stability,shape-memory capabilities,biocompatibility,biodegradability,and 3 D printing performance of PLLA-TMC-GA terpolymers with various compositions.The results indicate that PLLA-TMC-GA exhibits exceptional shape-memory performance,adjustable material properties,favorable biocompatibility,and the potential for controlled biodegradation and reabsorption.The use of PLLA-TMC-GA as a biodegradable shape-memory polymer allows the reduction of implant volume,simplifies implantation,and enables on-demand activation at body temperature.These characteristics present new opportunities for the advancement of minimally invasive surgical techniques.展开更多
Shape-memory polymers(SMPs)and their composite materials are stimuliresponsive materials that have the unique characteristics of lightweight,large deformation,variable stiffness,and biocompatibility.This paper reviews...Shape-memory polymers(SMPs)and their composite materials are stimuliresponsive materials that have the unique characteristics of lightweight,large deformation,variable stiffness,and biocompatibility.This paper reviews the research status of the mechanical models for SMPs,shape-memory nanocomposites and shape-memory polymer composites(SMPCs);it also introduces some spatially deployable structures,such as hinges,beams,and antennae based on SMPCs.In addition,the deformation types of 4D printing structures and the potential applications of this technology in robots and medical devices are also summarized.展开更多
Elemental titanium(Ti)and nickel(Ni)powders were consolidated by spark plasma sintering(SPS)to fabricate Ti-51%Ni(mole fraction)shape-memory alloys(SMAs).The objective of this study is to enhance the superelasticity o...Elemental titanium(Ti)and nickel(Ni)powders were consolidated by spark plasma sintering(SPS)to fabricate Ti-51%Ni(mole fraction)shape-memory alloys(SMAs).The objective of this study is to enhance the superelasticity of SPS produced Ti-Ni alloy using free forging as a secondary process.Products from two processes(with and without free forging)were compared in terms of microstructure,transformation temperature and superelasticity.The results showed that,free forging effectively improved the tensile and shape-memory properties.Ductility increased from 6.8%to 9.2%after forging.The maximum strain during superelasticity increased from 5%to 7.5%and the strain recovery rate increased from 72%to 92%.The microstructure of produced Ti-51%Ni SMA consists of the cubic austenite(B2)matrix,monoclinic martensite(B19′),secondary phases(Ti3Ni4,Ti2Ni and TiNi3)and oxides(Ti4Ni2O and Ti3O5).There was a shift towards higher temperatures in the martensitic transformation of free forged specimen(aged at 500°C)due to the decrease in Ni content of B2 matrix.This is related to the presence of Ti3Ni4 precipitates,which were observed using transmission electron microscope(TEM).In conclusion,free forging could improve superelasticity and mechanical properties of Ti-51%Ni SMA.展开更多
Nature has been inspiring material researchers to fabricate biomimetic functional devices for various applications, and shape-memory polymer materials(SMPMs) have received tremendous attention since the promising inte...Nature has been inspiring material researchers to fabricate biomimetic functional devices for various applications, and shape-memory polymer materials(SMPMs) have received tremendous attention since the promising intelligent materials possess more advantages over others for the fabrication of biomimetic functional devices. As is well-known, SMPMs can be stimulated by heat, electricity, magnetism, pH, solvent and light. From the viewpoint of practical applications, ultraviolet(UV)-visible(Vis)-near infrared(NIR) light-responsive SMPMs are undoubtedly more advantageous. However, up to now, UV-Vis-NIR light-deformable SMPMs by combining photothermal and photochemical effects are still rarely reported. Here we designed a UV-Vis-NIR light-deformable SMP composite film via incorporating a liquid crystal(LC) mixture and graphene oxide(GO) into a shape-memory polyurethane matrix. The elongated composite films exhibited interesting photomechanical bending deformations with different light-triggered mechanisms,(1) photochemically induced LC phase transition upon UV exposure,(2) photochemically and photothermally induced LC phase transition upon visible-light irradiation,(3) photothermally triggered LC phase transition and partial stress relaxation upon low-intensity NIR exposure. All the deformed objects could recover to their original shapes by high-intensity NIR irradiation.Moreover, the biomimetic circadian rhythms of acacia leaves and the biomimetic bending/spreading of fingers were successfully achieved, which could blaze a way in the field of biomimetic functional devices due to the excellent light-deformable and shape-memory properties of the SMP composite films.展开更多
3D porous scaffold could provide suitable bone-like structure for cell adhesion and proliferation;however,surgical suffering from large volume implantation is a great challenge for patients.In this study,a shape progr...3D porous scaffold could provide suitable bone-like structure for cell adhesion and proliferation;however,surgical suffering from large volume implantation is a great challenge for patients.In this study,a shape programmable porous poly(ε-caprolactone)(PCL)-based polyurethane scaffold with memory effect was synthesized via gas foaming method,using Citrate modified Amorphous calcium Phosphate(CAP)as bioactive factor.The bending experiments indicated that the scaffolds achieved excellent shape-memory effect,which could be influenced by particle weight content.In vitro mineralization results suggested that the deposition of hydroxyapatite was promoted by scaffolds.Additionally,cell assay showed that composite scaffolds presented good cell toxicity and osteogenicity by the differentiation of rat Mesenchymal Stem Cells(rMSCs)into the osteogenic lineage.In the model of rat cranial implantation,the reparative tissue covered the defect site and bone-like structure deposited on the scaffold due to the formation of new bones.In summary,the porous smart shape-memory composite scaffolds could be a potential candidate in future distinctive bone repair applications.展开更多
Shape-memory poly（p-dioxanone）–poly（e-caprolactone）/sepiolite（PPDO–PCL/OSEP） nanocomposites with different OSEP nanofiber loading were fabricated by chain-extending the PPDO-diol and PCL/OSEP precursors. The p...Shape-memory poly（p-dioxanone）–poly（e-caprolactone）/sepiolite（PPDO–PCL/OSEP） nanocomposites with different OSEP nanofiber loading were fabricated by chain-extending the PPDO-diol and PCL/OSEP precursors. The precursors and the composites were characterized by1 H NMR, FT-IR, GPC, SEM and TEM.The results demonstrate that a part of PCL segments grafted on the surface of OSEP and composites display a fine dispersion of OSEP fiber in nanoscale with low OSEP content. The shape memory effect（SME） was evaluated by DMA, the results reveal that the PPDO–PCL/OSEP nanocomposites exhibit desirable shape-memory performance. The reinforcement of composites by incorporation of trace OSEP nanofiber evokes an effective improvement in shape-memory recovery stress.展开更多
BACKGROUND Comminuted manubrium sterni fractures are rare,and internal fixation methods are limited.This report explored a practical and feasible method of internal fixation for comminuted manubrium sterni fractures.C...BACKGROUND Comminuted manubrium sterni fractures are rare,and internal fixation methods are limited.This report explored a practical and feasible method of internal fixation for comminuted manubrium sterni fractures.CASE SUMMARY A 17-year-old female was injured in a car accident for which she underwent debridement and suturing of her head and anterior chest wounds in another hospital.Eight days later,the patient was transferred to our hospital for surgical treatment.The manubrium sterni was found intraoperatively to be split into three irregular fragments with obvious overlap and separation displacement.Meanwhile,a manubriosternal joint dislocation and left first rib cartilage fracture were observed.The retraction force of the shape-memory alloy staples was used to pull the fracture fragments together.Two more titanium locking plates were then used to fix the manubrium sterni and corpus sterni longitudinally,and the left first rib cartilage fracture was repositioned and fixed with a titanium locking plate.A postoperative computed tomography scan showed reduced and rigid fixation of the comminuted manubrium sterni fractures.The patient recovered well with no significant complaints of discomfort.The patient was discharged 10 days postoperatively after the stitches had been removed.CONCLUSION Shape-memory alloy staples had the advantage of being safe and effective during the repositioning and internal fixation of comminuted manubrium sterni fractures.Therefore,they provided a new surgical option for comminuted manubrium sterni fractures.展开更多
Droplet manipulation plays a significant role in the fields of biomedical detection,microfluidics,and chemical engineering.However,it still remains a great challenge to simultaneously achieve remote,selective,and in s...Droplet manipulation plays a significant role in the fields of biomedical detection,microfluidics,and chemical engineering.However,it still remains a great challenge to simultaneously achieve remote,selective,and in situ droplet manipulation on the same surface.Here,Fe_(3)O_(4)nanoparticles were doped in a shape-memory polymer(SMP)to prepare a photothermal-responsive Fe_(3)O_(4)-SMP composite which showed remarkable near-infrared(NIR)light-triggered shape-memory property.Superhydrophobic micropillar array was constructed on such Fe_(3)O_(4)-SMP composite through femtosecond laser microfabrication and fluoroalkylsilane modification.The surface wettability of the as-prepared surface can transform from a low-adhesive sliding state to a high-adhesive pinning state as the micropillars are deformed by pressing.Interestingly,the deformed micropillars can stand up and restore to their original morphology under remote NIR light irradiation,resulting in the reversible and repeatable recovery of the ultralow-adhesive superhydrophobicity.With such light-triggered wettability switching,the droplets pinning on the sample surface can be remotely,selectively,and in situ released.Furthermore,the superhydrophobic Fe_(3)O_(4)-SMP surface is successfully applied in lossless liquid transfer,selective droplet release,and droplet-based microreactor.The as-fabricated superhydrophobic surfaces with NIR light-controlled reversible wettability will hold great promise in the fields of liquid manipulation,lab-on-a-chip,and microfluidics.展开更多
Structural colors,derived from existing natural creatures,have aroused widespread attention in the materials regulation for different applications.Here,inspired by the color adjusting mechanism of hummingbird,we prese...Structural colors,derived from existing natural creatures,have aroused widespread attention in the materials regulation for different applications.Here,inspired by the color adjusting mechanism of hummingbird,we present a novel shape-memory structural color hydrogel film by introducing shape memory polymers(SMPs)into synthetic inverse opal scaffold structure.The excellent flexibility as well as the inverse opal structure of the hydrogel films imparts them with stable stretchability and brilliant structural colors.Benefiting from the transient structural anisotropy of copolymers,the hybrid films are possessed with shape-morphing behaviors capability.Based on the shape transformations and color responsiveness performance,we have demonstrated diverse structural color actuators with complex shapes for different tasks.Notably,as the photothermal responsive graphene quantum dots were integrated into the hydrogel,the hybrid films could also be endowed with the feature of light-controlled reversible deformation with synchronous structural color variation.These features demonstrate that the presented shape-memory structural color hydrogel film is valuable for soft robotics with multifunctions of sensing,communication and disguise.展开更多
Severe ischemic stroke damages neuronal tissue,forming irregular-shaped stroke cavities devoid of supporting structure.Implanting biomaterials to provide structural and functional support is thought to favor ingrowth ...Severe ischemic stroke damages neuronal tissue,forming irregular-shaped stroke cavities devoid of supporting structure.Implanting biomaterials to provide structural and functional support is thought to favor ingrowth of regenerated neuronal networks.Injectable hydrogels capable of in situ gelation are often utilized for stroke repair,but challenged by incomplete gelation and imprecise control over end-macrostructure.Injectable shape-memory scaffolds might overcome these limitations,but are not explored for stroke repair.Here,we report an injectable,photoluminescent,carbon-nanotubes-doped sericin scaffold(CNTs-SS)with programmable shape-memory property.By adjusting CNTs’concentrations,CNTs-SS′recovery dynamics can be mathematically calculated at the scale of seconds,and its shapes can be pre-designed to precisely match any irregular-shaped cavities.Using a preclinical stroke model,we show that CNTs-SS with the customized shape is successfully injected into the cavity and recovers its pre-designed shape to well fit the cavity.Notably,CNTs-SS’near-infrared photoluminescence enables non-invasive,real-time tracking after in vivo implantation.Moreover,as a cell carrier,CNTs-SS not only deliver bone marrow mesenchymal stem cells(BMSCs)into brain tissues,but also functionally promote their neuronal differentiation.Together,we for the first time demonstrate the feasibility of applying injectable shape-memory scaffolds for stroke repair,paving the way for personalized stroke repair.展开更多
Space masts are widely used in the aerospace engineering as one type of deployable space structures.In this paper,based on the stimuli-responsive effects of shape-memory polymers(SMPs),an intelligent mast with shape-m...Space masts are widely used in the aerospace engineering as one type of deployable space structures.In this paper,based on the stimuli-responsive effects of shape-memory polymers(SMPs),an intelligent mast with shape-memory function is studied.The thermos-mechanical constitutive model of SMPs is associated with the finite element(FE)software,and then the deployable deformation and shape-memory effect of the intelligent mast are investigated by the FE method.It is demonstrated that the mast can automatically deploy due to the shape recovery characteristics of SMPs.Furthermore,the effects of structure parametric of the mast and temperature are also investigated.The results can contribute to the design and application of novel SMP masts.展开更多
A conductive carbon nanofiber(CNF)paper is described for the actuation of shape recovery of a shape-memory polymer(SMP)by electrically resistive Joule heating.The CNF paper was manufactured using a traditional physica...A conductive carbon nanofiber(CNF)paper is described for the actuation of shape recovery of a shape-memory polymer(SMP)by electrically resistive Joule heating.The CNF paper was manufactured using a traditional physical vapor deposition process and the microscale morphology and structure of the CNF paper were observed using a scanning electron microscope.The CNF paper was found to be porous,with the pore size determined by the weight concentration of CNF.The excellent electrical properties of pure CNF papers and their SMP composites were characterized by the four-point probe method.Shape recovery actuation of this type of SMP composite induced by electrically resistive heating was achieved with a 12 V voltage.Additionally,the thermomechanical properties of the SMP composite were studied with respect to the volume fraction of CNF paper.展开更多
Thermal energy storage has been a pivotal technology to fill the gap between energy demands and energy supplies.As a solid-solid phase change material,shape-memory alloys(SMAs)have the inherent advantages of leakage f...Thermal energy storage has been a pivotal technology to fill the gap between energy demands and energy supplies.As a solid-solid phase change material,shape-memory alloys(SMAs)have the inherent advantages of leakage free,no encapsulation,negligible volume variation,as well as superior energy storage properties such as high thermal conductivity(compared with ice and paraffin)and volumetric energy density,making them excellent thermal energy storage materials.Considering these characteristics,the design of the shape-memory alloy based the cold thermal energy storage system for precooling car seat application is introduced in this paper based on the proposed shape-memory alloy-based cold thermal energy storage cycle.The simulation results show that the minimum temperature of the metal boss under the seat reaches 26.2°C at 9.85 s,which is reduced by 9.8°C,and the energy storage efficiency of the device is 66%.The influence of initial temperature,elastocaloric materials,and the shape-memory alloy geometry scheme on the performance of car seat cold thermal energy storage devices is also discussed.Since SMAs are both solid-state refrigerants and thermal energy storage materials,hopefully the proposed concept can promote the development of more promising shape-memory alloy-based cold and hot thermal energy storage devices.展开更多
Shape-memory polymers(SMPs)are one of the most popular smart materials due to their light weight and high elastic deformation capability.The synergistic effect of carbon nanofiber(CNF)and carbon nanofiber paper(CNFP)o...Shape-memory polymers(SMPs)are one of the most popular smart materials due to their light weight and high elastic deformation capability.The synergistic effect of carbon nanofiber(CNF)and carbon nanofiber paper(CNFP)on the electro-actuation of SMP nanocomposites was studied.The electrical conductivity of SMPs was significantly improved by incorporating CNF and CNFP into them.The dynamic mechanical analysis result reveals good thermal stability of SMP nanocomposites even after they were mixed with CNFs.A vision-based control system is designed to precisely control the shape recovery of SMP composites.Any quasi-state shape between the permanent shape and a temporary shape can be achieved by adjusting the electrical energy input.Experimental results demonstrated that(1)compared with the baseline material,the full recovery time of the SMP nanocomposites was decreased by 1000%to less than 80 s;(2)a good repeatability was shown in the developed vision system in 10 experimental trials and the accuracy of the controlled deflection angle of SMPs was within a 5%error bound.展开更多
A shape-memory double network hydrogel consists of two polymer networks:a chemically crosslinked primary network that is responsible for the permanent shape and a physically crosslinked secondary network that is used ...A shape-memory double network hydrogel consists of two polymer networks:a chemically crosslinked primary network that is responsible for the permanent shape and a physically crosslinked secondary network that is used to fix the temporary shapes.The formation/melting transition of the secondary network serves as an effective mechanism for the double network hydrogel’s shape-memory effect.When the crosslinks in the secondary network are dissociated by applying an external stimulus,only the primary network is left to support the load.When the secondary network is re-formed by removing the stimulus,both the primary and secondary networks support the load.In the past,models have been developed for the constitutive behaviors of double network hydrogels,but the model of shape-memory double network hydrogels is still lacking.This work aims to build a constitutive model for the polyacrylamide-gelatin double network shape-memory hydrogel developed in our previous work.The model is first calibrated by experimental data of the double network shape-memory hydrogel under uniaxial loading and then employed to predict the shape-fixing performance of the hydrogel.The model is also implemented into a three-dimension finite element code and utilized to simulate the shape-memory behavior of the double network hydrogel with inhomogeneous deformations related to applications.展开更多
The four-dimensional(4D) printing technology, as a combination of additive manufacturing and smart materials, has attracted increasing research interest in recent years. The bilayer structures printed with smart mater...The four-dimensional(4D) printing technology, as a combination of additive manufacturing and smart materials, has attracted increasing research interest in recent years. The bilayer structures printed with smart materials using this technology can realize complicated deformation under some special stimuli due to the material properties.The deformation prediction of bilayer structures can make the design process more rapid and thus is of great importance. However, the previous works on deformation prediction of bilayer structures rarely study the complicated deformations or the influence of the printing process on deformation. Thus, this paper proposes a new method to predict the complicated deformations of temperature-sensitive 4D printed bilayer structures,in particular to the bilayer structures based on temperature-driven shape-memory polymers(SMPs) and fabricated using the fused deposition modeling(FDM) technology. The programming process to the material during printing is revealed and considered in the simulation model. Simulation results are compared with experiments to verify the validity of the method. The advantages of this method are stable convergence and high efficiency,as the three-dimensional(3D) problem is converted to a two-dimensional(2D) problem.The simulation parameters in the model can be further associated with the printing parameters, which shows good application prospect in 4D printed bilayer structure design.展开更多
The structures, the martensitic transformations, and the magnetic properties are studied systematically in Mn50Ni40-xCuxIn10, Mn50-xCuxNi40In10, and Mn50Ni40In10-xCux alloys. The partial substitution of Ni by Cu reduc...The structures, the martensitic transformations, and the magnetic properties are studied systematically in Mn50Ni40-xCuxIn10, Mn50-xCuxNi40In10, and Mn50Ni40In10-xCux alloys. The partial substitution of Ni by Cu reduces the martensitic transformation temperature, but has little influence on the Curie temperature of austenite. Comparatively, the martensitic transformation temperature increases and the Curie temperature of austenite decreases with the partial replacement of Mn or In by Cu. The magnetization difference between the austenite phase and the martensite phase reaches 70 emu/g in Mn50Ni39Cu1In10; a field-induced martensite-to-austenite transition is observed in this alloy.展开更多
The microstructure of CosoNi22Ga28 ribbon with the L10 structure is examined. The band-like morphology is observed. These bands with the width in a range of 40-200 nm appear along the transverse direction of the ribbo...The microstructure of CosoNi22Ga28 ribbon with the L10 structure is examined. The band-like morphology is observed. These bands with the width in a range of 40-200 nm appear along the transverse direction of the ribbon. The giant magnetoimpedance （GMI） effect in this alloy is measured. The results show that Co5oNi22Ga28 exhibits a sharp peak of the GAI effect. The maximum GAH ratio up to 360% is detected. The GMI effect measured versus temperature shows large jumps of the magnetoimpedance amplitude at the reversal martensitic transformation temperature 240℃ and Curie temperature 375℃C respectively. The jump ratios of the magnetoimpedance amplitude examined at these temperatures are about 5 and 10, respectively.展开更多
Non-stoichiometric Ni50Mn27 Ga23 polycrystalline ribbons are prepared by melt-spinning technique. The magneticfield-induced strain （MFIS） of Ni-Mn-Ga bulk alloy prepared by bonding the melt-spun ribbons is obtained....Non-stoichiometric Ni50Mn27 Ga23 polycrystalline ribbons are prepared by melt-spinning technique. The magneticfield-induced strain （MFIS） of Ni-Mn-Ga bulk alloy prepared by bonding the melt-spun ribbons is obtained. The experimental results show that Ni50Mn27Ga23 bonded ribbons exhibit a typical thermal-elastic shape memory effect in the thickness direction. The martensitic transformation strain of bonded ribbons is an expansive strain of about 0.3% without the magnetic field and a contractive strain of about -0.46% at the magnetic field of 1 T. The field can not only enhance the value of the martensitic transformation strain of the bonded ribbons, but can also change the direction of the strain. The bonded ribbons alloy presents negative MFIS and obtains a larger value of the strain though influenced by the adhesive between the ribbons. Therefore, the preparation technique of the Ni-Mn-Ga bulk alloy by bonding melt-spun ribbons is helpful to get rid of the size restriction of the ribbon and to broaden the applications of the ribbons.展开更多
基金supported by the National Natural Science Foundation of China(Nos.82402822,82360427,82372425,82072443,and 32200559)the Priority Union Foundation of Yunnan Provincial Science and Technology Department and Kunming Medical University(No.202301AY070001-164)+1 种基金the Natural Science Foundation of Sichuan Province(No.23NSFSC5880)the Central Government of Sichuan Province Guiding the Special Project of Local Science and Technology Development(No.2024ZYD0155).
文摘Three-dimensional(3 D)printing has revolutionized the design and production of customized scaffolds,but the minimally invasive implantation of 3 D-printed structures into the human body remains challenging.This has prompted the exploration of innovative materials and technical solutions.Shape-memory polymers,as advanced intelligent materials,exhibit considerable potential in minimally invasive surgical applications.Herein,we developed a novel thermosetting shape-memory polymer,poly(L-lactic acid)-trimethylene carbonate-glycolic acid(PLLA-TMC-GA),for the fabrication of bioengineered scaffolds with body temperature-activated shape-memory functionality.We comprehensively evaluated the mechanical properties,thermal stability,shape-memory capabilities,biocompatibility,biodegradability,and 3 D printing performance of PLLA-TMC-GA terpolymers with various compositions.The results indicate that PLLA-TMC-GA exhibits exceptional shape-memory performance,adjustable material properties,favorable biocompatibility,and the potential for controlled biodegradation and reabsorption.The use of PLLA-TMC-GA as a biodegradable shape-memory polymer allows the reduction of implant volume,simplifies implantation,and enables on-demand activation at body temperature.These characteristics present new opportunities for the advancement of minimally invasive surgical techniques.
基金This work is supported by the National Natural Science Foundation of China(Grant Nos.11772109,11632005 and 11672086)the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(Grant No.11421091).
文摘Shape-memory polymers(SMPs)and their composite materials are stimuliresponsive materials that have the unique characteristics of lightweight,large deformation,variable stiffness,and biocompatibility.This paper reviews the research status of the mechanical models for SMPs,shape-memory nanocomposites and shape-memory polymer composites(SMPCs);it also introduces some spatially deployable structures,such as hinges,beams,and antennae based on SMPCs.In addition,the deformation types of 4D printing structures and the potential applications of this technology in robots and medical devices are also summarized.
基金the Ministry of Higher Education of Malaysia for the Malaysian International Scholarship and research funding under FRGS vote No. R.J13000.7824.4F810
文摘Elemental titanium(Ti)and nickel(Ni)powders were consolidated by spark plasma sintering(SPS)to fabricate Ti-51%Ni(mole fraction)shape-memory alloys(SMAs).The objective of this study is to enhance the superelasticity of SPS produced Ti-Ni alloy using free forging as a secondary process.Products from two processes(with and without free forging)were compared in terms of microstructure,transformation temperature and superelasticity.The results showed that,free forging effectively improved the tensile and shape-memory properties.Ductility increased from 6.8%to 9.2%after forging.The maximum strain during superelasticity increased from 5%to 7.5%and the strain recovery rate increased from 72%to 92%.The microstructure of produced Ti-51%Ni SMA consists of the cubic austenite(B2)matrix,monoclinic martensite(B19′),secondary phases(Ti3Ni4,Ti2Ni and TiNi3)and oxides(Ti4Ni2O and Ti3O5).There was a shift towards higher temperatures in the martensitic transformation of free forged specimen(aged at 500°C)due to the decrease in Ni content of B2 matrix.This is related to the presence of Ti3Ni4 precipitates,which were observed using transmission electron microscope(TEM).In conclusion,free forging could improve superelasticity and mechanical properties of Ti-51%Ni SMA.
基金financially supported by the National Natural Science Foundation of China(Nos.51373025,51773002 and 51921002)。
文摘Nature has been inspiring material researchers to fabricate biomimetic functional devices for various applications, and shape-memory polymer materials(SMPMs) have received tremendous attention since the promising intelligent materials possess more advantages over others for the fabrication of biomimetic functional devices. As is well-known, SMPMs can be stimulated by heat, electricity, magnetism, pH, solvent and light. From the viewpoint of practical applications, ultraviolet(UV)-visible(Vis)-near infrared(NIR) light-responsive SMPMs are undoubtedly more advantageous. However, up to now, UV-Vis-NIR light-deformable SMPMs by combining photothermal and photochemical effects are still rarely reported. Here we designed a UV-Vis-NIR light-deformable SMP composite film via incorporating a liquid crystal(LC) mixture and graphene oxide(GO) into a shape-memory polyurethane matrix. The elongated composite films exhibited interesting photomechanical bending deformations with different light-triggered mechanisms,(1) photochemically induced LC phase transition upon UV exposure,(2) photochemically and photothermally induced LC phase transition upon visible-light irradiation,(3) photothermally triggered LC phase transition and partial stress relaxation upon low-intensity NIR exposure. All the deformed objects could recover to their original shapes by high-intensity NIR irradiation.Moreover, the biomimetic circadian rhythms of acacia leaves and the biomimetic bending/spreading of fingers were successfully achieved, which could blaze a way in the field of biomimetic functional devices due to the excellent light-deformable and shape-memory properties of the SMP composite films.
基金supported by the National Natural Science Foundation of China(NO.41673109)Sichuan Science and Technology Program(2021YFH0098)+2 种基金Sichuan University Panzhihua school city strategic cooperation special fund project(2019CDPZH-6)the Science and Technology Department Project of Sichuan Province(2018SZDZX0022)Key Project of Sichuan Vanadium and Titanium Industry Development Research Center(2018VTCY-Z-01).
文摘3D porous scaffold could provide suitable bone-like structure for cell adhesion and proliferation;however,surgical suffering from large volume implantation is a great challenge for patients.In this study,a shape programmable porous poly(ε-caprolactone)(PCL)-based polyurethane scaffold with memory effect was synthesized via gas foaming method,using Citrate modified Amorphous calcium Phosphate(CAP)as bioactive factor.The bending experiments indicated that the scaffolds achieved excellent shape-memory effect,which could be influenced by particle weight content.In vitro mineralization results suggested that the deposition of hydroxyapatite was promoted by scaffolds.Additionally,cell assay showed that composite scaffolds presented good cell toxicity and osteogenicity by the differentiation of rat Mesenchymal Stem Cells(rMSCs)into the osteogenic lineage.In the model of rat cranial implantation,the reparative tissue covered the defect site and bone-like structure deposited on the scaffold due to the formation of new bones.In summary,the porous smart shape-memory composite scaffolds could be a potential candidate in future distinctive bone repair applications.
基金supported financially by the National Science Foundation of China (Nos. 51473096, 51421061, J1103315)Program for Changjiang Scholars and Innovative Research Team in University of Ministry of Education of China (No. IRT 1026)
文摘Shape-memory poly（p-dioxanone）–poly（e-caprolactone）/sepiolite（PPDO–PCL/OSEP） nanocomposites with different OSEP nanofiber loading were fabricated by chain-extending the PPDO-diol and PCL/OSEP precursors. The precursors and the composites were characterized by1 H NMR, FT-IR, GPC, SEM and TEM.The results demonstrate that a part of PCL segments grafted on the surface of OSEP and composites display a fine dispersion of OSEP fiber in nanoscale with low OSEP content. The shape memory effect（SME） was evaluated by DMA, the results reveal that the PPDO–PCL/OSEP nanocomposites exhibit desirable shape-memory performance. The reinforcement of composites by incorporation of trace OSEP nanofiber evokes an effective improvement in shape-memory recovery stress.
基金Supported by Shenyang Medical College Youth Scientific Research Fund,No.20202027.
文摘BACKGROUND Comminuted manubrium sterni fractures are rare,and internal fixation methods are limited.This report explored a practical and feasible method of internal fixation for comminuted manubrium sterni fractures.CASE SUMMARY A 17-year-old female was injured in a car accident for which she underwent debridement and suturing of her head and anterior chest wounds in another hospital.Eight days later,the patient was transferred to our hospital for surgical treatment.The manubrium sterni was found intraoperatively to be split into three irregular fragments with obvious overlap and separation displacement.Meanwhile,a manubriosternal joint dislocation and left first rib cartilage fracture were observed.The retraction force of the shape-memory alloy staples was used to pull the fracture fragments together.Two more titanium locking plates were then used to fix the manubrium sterni and corpus sterni longitudinally,and the left first rib cartilage fracture was repositioned and fixed with a titanium locking plate.A postoperative computed tomography scan showed reduced and rigid fixation of the comminuted manubrium sterni fractures.The patient recovered well with no significant complaints of discomfort.The patient was discharged 10 days postoperatively after the stitches had been removed.CONCLUSION Shape-memory alloy staples had the advantage of being safe and effective during the repositioning and internal fixation of comminuted manubrium sterni fractures.Therefore,they provided a new surgical option for comminuted manubrium sterni fractures.
基金This work was supported by the National Key Research and Development Program of China(2017YFB1104700)the National Natural Science Foundation of China(61875158)the International Joint Research Laboratory for Micro/Nano Manufacturing and Measurement Technologies,the Fundamental Research Funds for the Central Universities.
文摘Droplet manipulation plays a significant role in the fields of biomedical detection,microfluidics,and chemical engineering.However,it still remains a great challenge to simultaneously achieve remote,selective,and in situ droplet manipulation on the same surface.Here,Fe_(3)O_(4)nanoparticles were doped in a shape-memory polymer(SMP)to prepare a photothermal-responsive Fe_(3)O_(4)-SMP composite which showed remarkable near-infrared(NIR)light-triggered shape-memory property.Superhydrophobic micropillar array was constructed on such Fe_(3)O_(4)-SMP composite through femtosecond laser microfabrication and fluoroalkylsilane modification.The surface wettability of the as-prepared surface can transform from a low-adhesive sliding state to a high-adhesive pinning state as the micropillars are deformed by pressing.Interestingly,the deformed micropillars can stand up and restore to their original morphology under remote NIR light irradiation,resulting in the reversible and repeatable recovery of the ultralow-adhesive superhydrophobicity.With such light-triggered wettability switching,the droplets pinning on the sample surface can be remotely,selectively,and in situ released.Furthermore,the superhydrophobic Fe_(3)O_(4)-SMP surface is successfully applied in lossless liquid transfer,selective droplet release,and droplet-based microreactor.The as-fabricated superhydrophobic surfaces with NIR light-controlled reversible wettability will hold great promise in the fields of liquid manipulation,lab-on-a-chip,and microfluidics.
基金supported by the National Key Research and Development Program of China(2020YFA0908200)the National Natural Science Foundation of China(52073060 and 61927805)+1 种基金the Shenzhen Fundamental Research Program(JCYJ20190813152616459)the Project funded by China Postdoctoral Science Foundation。
文摘Structural colors,derived from existing natural creatures,have aroused widespread attention in the materials regulation for different applications.Here,inspired by the color adjusting mechanism of hummingbird,we present a novel shape-memory structural color hydrogel film by introducing shape memory polymers(SMPs)into synthetic inverse opal scaffold structure.The excellent flexibility as well as the inverse opal structure of the hydrogel films imparts them with stable stretchability and brilliant structural colors.Benefiting from the transient structural anisotropy of copolymers,the hybrid films are possessed with shape-morphing behaviors capability.Based on the shape transformations and color responsiveness performance,we have demonstrated diverse structural color actuators with complex shapes for different tasks.Notably,as the photothermal responsive graphene quantum dots were integrated into the hydrogel,the hybrid films could also be endowed with the feature of light-controlled reversible deformation with synchronous structural color variation.These features demonstrate that the presented shape-memory structural color hydrogel film is valuable for soft robotics with multifunctions of sensing,communication and disguise.
基金This work was supported by the National Key Basic Research Program of China[2015CB5540007]the National Natural Science Foundation of China[81671904,81572866,81773104,and 81873931]+3 种基金the Science and Technology Program of Chinese Ministry of Education[113044A]the Major Scientific and Technological Innovation Projects in Hubei Province[2018ACA136]the Integrated Innovative Team for Major Human Diseases Program of Tongji Medical College of HUSTthe Academic Doctor Supporting Program of Tongji Medical College of HUST.
文摘Severe ischemic stroke damages neuronal tissue,forming irregular-shaped stroke cavities devoid of supporting structure.Implanting biomaterials to provide structural and functional support is thought to favor ingrowth of regenerated neuronal networks.Injectable hydrogels capable of in situ gelation are often utilized for stroke repair,but challenged by incomplete gelation and imprecise control over end-macrostructure.Injectable shape-memory scaffolds might overcome these limitations,but are not explored for stroke repair.Here,we report an injectable,photoluminescent,carbon-nanotubes-doped sericin scaffold(CNTs-SS)with programmable shape-memory property.By adjusting CNTs’concentrations,CNTs-SS′recovery dynamics can be mathematically calculated at the scale of seconds,and its shapes can be pre-designed to precisely match any irregular-shaped cavities.Using a preclinical stroke model,we show that CNTs-SS with the customized shape is successfully injected into the cavity and recovers its pre-designed shape to well fit the cavity.Notably,CNTs-SS’near-infrared photoluminescence enables non-invasive,real-time tracking after in vivo implantation.Moreover,as a cell carrier,CNTs-SS not only deliver bone marrow mesenchymal stem cells(BMSCs)into brain tissues,but also functionally promote their neuronal differentiation.Together,we for the first time demonstrate the feasibility of applying injectable shape-memory scaffolds for stroke repair,paving the way for personalized stroke repair.
基金supported by the National Natural Science Foundation of China[Project Number 11632005,11772012,and 11872079].
文摘Space masts are widely used in the aerospace engineering as one type of deployable space structures.In this paper,based on the stimuli-responsive effects of shape-memory polymers(SMPs),an intelligent mast with shape-memory function is studied.The thermos-mechanical constitutive model of SMPs is associated with the finite element(FE)software,and then the deployable deformation and shape-memory effect of the intelligent mast are investigated by the FE method.It is demonstrated that the mast can automatically deploy due to the shape recovery characteristics of SMPs.Furthermore,the effects of structure parametric of the mast and temperature are also investigated.The results can contribute to the design and application of novel SMP masts.
文摘A conductive carbon nanofiber(CNF)paper is described for the actuation of shape recovery of a shape-memory polymer(SMP)by electrically resistive Joule heating.The CNF paper was manufactured using a traditional physical vapor deposition process and the microscale morphology and structure of the CNF paper were observed using a scanning electron microscope.The CNF paper was found to be porous,with the pore size determined by the weight concentration of CNF.The excellent electrical properties of pure CNF papers and their SMP composites were characterized by the four-point probe method.Shape recovery actuation of this type of SMP composite induced by electrically resistive heating was achieved with a 12 V voltage.Additionally,the thermomechanical properties of the SMP composite were studied with respect to the volume fraction of CNF paper.
基金supported by the National Natural Science Foundation of China(Grant No.51976149)the Young Elite Scientists Sponsorship Program by China Association for Science and Technology(Grant No.2019QNRC001).
文摘Thermal energy storage has been a pivotal technology to fill the gap between energy demands and energy supplies.As a solid-solid phase change material,shape-memory alloys(SMAs)have the inherent advantages of leakage free,no encapsulation,negligible volume variation,as well as superior energy storage properties such as high thermal conductivity(compared with ice and paraffin)and volumetric energy density,making them excellent thermal energy storage materials.Considering these characteristics,the design of the shape-memory alloy based the cold thermal energy storage system for precooling car seat application is introduced in this paper based on the proposed shape-memory alloy-based cold thermal energy storage cycle.The simulation results show that the minimum temperature of the metal boss under the seat reaches 26.2°C at 9.85 s,which is reduced by 9.8°C,and the energy storage efficiency of the device is 66%.The influence of initial temperature,elastocaloric materials,and the shape-memory alloy geometry scheme on the performance of car seat cold thermal energy storage devices is also discussed.Since SMAs are both solid-state refrigerants and thermal energy storage materials,hopefully the proposed concept can promote the development of more promising shape-memory alloy-based cold and hot thermal energy storage devices.
文摘Shape-memory polymers(SMPs)are one of the most popular smart materials due to their light weight and high elastic deformation capability.The synergistic effect of carbon nanofiber(CNF)and carbon nanofiber paper(CNFP)on the electro-actuation of SMP nanocomposites was studied.The electrical conductivity of SMPs was significantly improved by incorporating CNF and CNFP into them.The dynamic mechanical analysis result reveals good thermal stability of SMP nanocomposites even after they were mixed with CNFs.A vision-based control system is designed to precisely control the shape recovery of SMP composites.Any quasi-state shape between the permanent shape and a temporary shape can be achieved by adjusting the electrical energy input.Experimental results demonstrated that(1)compared with the baseline material,the full recovery time of the SMP nanocomposites was decreased by 1000%to less than 80 s;(2)a good repeatability was shown in the developed vision system in 10 experimental trials and the accuracy of the controlled deflection angle of SMPs was within a 5%error bound.
基金supported by the Air Force Office of Scientific Research under Award(Grant FA9550-19-1-0395)the National Science Foundation(Grant 1935154)。
文摘A shape-memory double network hydrogel consists of two polymer networks:a chemically crosslinked primary network that is responsible for the permanent shape and a physically crosslinked secondary network that is used to fix the temporary shapes.The formation/melting transition of the secondary network serves as an effective mechanism for the double network hydrogel’s shape-memory effect.When the crosslinks in the secondary network are dissociated by applying an external stimulus,only the primary network is left to support the load.When the secondary network is re-formed by removing the stimulus,both the primary and secondary networks support the load.In the past,models have been developed for the constitutive behaviors of double network hydrogels,but the model of shape-memory double network hydrogels is still lacking.This work aims to build a constitutive model for the polyacrylamide-gelatin double network shape-memory hydrogel developed in our previous work.The model is first calibrated by experimental data of the double network shape-memory hydrogel under uniaxial loading and then employed to predict the shape-fixing performance of the hydrogel.The model is also implemented into a three-dimension finite element code and utilized to simulate the shape-memory behavior of the double network hydrogel with inhomogeneous deformations related to applications.
基金the National Natural Science Foundation of China(Nos.52130501 and 52075479)the National Key R&D Program of China(No.2018YFB1700804)。
文摘The four-dimensional(4D) printing technology, as a combination of additive manufacturing and smart materials, has attracted increasing research interest in recent years. The bilayer structures printed with smart materials using this technology can realize complicated deformation under some special stimuli due to the material properties.The deformation prediction of bilayer structures can make the design process more rapid and thus is of great importance. However, the previous works on deformation prediction of bilayer structures rarely study the complicated deformations or the influence of the printing process on deformation. Thus, this paper proposes a new method to predict the complicated deformations of temperature-sensitive 4D printed bilayer structures,in particular to the bilayer structures based on temperature-driven shape-memory polymers(SMPs) and fabricated using the fused deposition modeling(FDM) technology. The programming process to the material during printing is revealed and considered in the simulation model. Simulation results are compared with experiments to verify the validity of the method. The advantages of this method are stable convergence and high efficiency,as the three-dimensional(3D) problem is converted to a two-dimensional(2D) problem.The simulation parameters in the model can be further associated with the printing parameters, which shows good application prospect in 4D printed bilayer structure design.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.51001010 and 11174030)the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20100006120001)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry of China
文摘The structures, the martensitic transformations, and the magnetic properties are studied systematically in Mn50Ni40-xCuxIn10, Mn50-xCuxNi40In10, and Mn50Ni40In10-xCux alloys. The partial substitution of Ni by Cu reduces the martensitic transformation temperature, but has little influence on the Curie temperature of austenite. Comparatively, the martensitic transformation temperature increases and the Curie temperature of austenite decreases with the partial replacement of Mn or In by Cu. The magnetization difference between the austenite phase and the martensite phase reaches 70 emu/g in Mn50Ni39Cu1In10; a field-induced martensite-to-austenite transition is observed in this alloy.
基金Supported by the National High Technology Research and Development Programme of China under Grant No 2003AA327010, and the National Natural Science Foundation of China under Grant No 60271028.
文摘The microstructure of CosoNi22Ga28 ribbon with the L10 structure is examined. The band-like morphology is observed. These bands with the width in a range of 40-200 nm appear along the transverse direction of the ribbon. The giant magnetoimpedance （GMI） effect in this alloy is measured. The results show that Co5oNi22Ga28 exhibits a sharp peak of the GAI effect. The maximum GAH ratio up to 360% is detected. The GMI effect measured versus temperature shows large jumps of the magnetoimpedance amplitude at the reversal martensitic transformation temperature 240℃ and Curie temperature 375℃C respectively. The jump ratios of the magnetoimpedance amplitude examined at these temperatures are about 5 and 10, respectively.
文摘Non-stoichiometric Ni50Mn27 Ga23 polycrystalline ribbons are prepared by melt-spinning technique. The magneticfield-induced strain （MFIS） of Ni-Mn-Ga bulk alloy prepared by bonding the melt-spun ribbons is obtained. The experimental results show that Ni50Mn27Ga23 bonded ribbons exhibit a typical thermal-elastic shape memory effect in the thickness direction. The martensitic transformation strain of bonded ribbons is an expansive strain of about 0.3% without the magnetic field and a contractive strain of about -0.46% at the magnetic field of 1 T. The field can not only enhance the value of the martensitic transformation strain of the bonded ribbons, but can also change the direction of the strain. The bonded ribbons alloy presents negative MFIS and obtains a larger value of the strain though influenced by the adhesive between the ribbons. Therefore, the preparation technique of the Ni-Mn-Ga bulk alloy by bonding melt-spun ribbons is helpful to get rid of the size restriction of the ribbon and to broaden the applications of the ribbons.
