Mechanochromic polyolefins represent a novel class of functionalized polyolefins,which still remains significant challenges.Pd(II)-catalyzed coordination-insertion copolymerization is a feasible method for achieving t...Mechanochromic polyolefins represent a novel class of functionalized polyolefins,which still remains significant challenges.Pd(II)-catalyzed coordination-insertion copolymerization is a feasible method for achieving this kind of polymers,yet with linear microstructures.Ringopening metathesis polymerization(ROMP)offers another promising avenue for affording functionalized polyolefins.This method exhibits high polar group tolerance and the ability to precisely regulate polymer branches.In this study,we report the method for producing mechanochromic branched polyethylenes via ROMP.By employing the terpolymerization of a well-designed monomer containing the mechanochromic group,NB-ABF,with cyclooctene(COE)and long-chain 5-hexylcyclooctene(COE-C6),following by hydrogenation process,we synthesized a range of functionalized branched polyethylenes characterized by varied branching density and polar monomer incorporation.These polymers bear a structural resemblance to functionalized ethylene-octene copolymers.After crosslinking,mechanochromophores are generated,and mechanochromism is achieved in uniaxial tensile testing.A comprehensive assessment reveals that both the incorporation of polar monomers and variations in branching density significantly influence their mechanical properties.Notably,upon stretching,these materials display pronounced visible color change,confirming the successful development of mechanochromic branched polyethylenes.展开更多
Short chain branching has been characterized using thermal fractionation, a stepwise isothermal crystallizationtechnique, followed by a melting analysis scan using differential scanning calorimetry. Short chain branch...Short chain branching has been characterized using thermal fractionation, a stepwise isothermal crystallizationtechnique, followed by a melting analysis scan using differential scanning calorimetry. Short chain branching distributionwas also characterized by a continuous slow cooling crystallization, followed by a melting analysis scan. Four differentpolyethylenes were studied: Ziegler-Natta gas phase, Ziegler-Natta solution, metallocene, constrained-geometry single sitecatalyzed polyethylenes. The branching distribution was calculated from a calibration of branch content with meltingtemperature. The lamellar thickness was calculated based on the thermodynamic melting temperature of each polyethyleneand the surface free energy of the crystal face. The branching distribution and lamellar thickness distribution were used tocalculate weight average branch content, mean lamellar thickness, and a branch dispersity index. The results for the branchcontent were in good agreement with the known comonomer content of the polyethylenes. A limitation was that high branchcontent polyethylenes did not reach their potential crystallization at ambient temperatures. Cooling to sub-ambient wasnecessary to equilibrate the crystallization, but melting temperature versus branch content was not applicable after cooling tobelow ambient because the calibration data were not performed in this way.展开更多
Seven new binuclear titanocenes with different linking bridges, unsubstituted or substituted on the Cp rings, were synthesized and tested for their effect on ethylene polymerization in the presence of MAO. The polyeth...Seven new binuclear titanocenes with different linking bridges, unsubstituted or substituted on the Cp rings, were synthesized and tested for their effect on ethylene polymerization in the presence of MAO. The polyethylenes thus obtained had broad MWD or even bimodal GPC curves, as compared with that from two reference mononuclear titanocenes. This is explained by the difference in degree of steric hindrance around the active center sites imposed by the bulky substituted ligands assuming different configurations in the rotation of the catalyst molecules. Lower polymerization temperatures alleviate the effect of these configuration differences, as reflected in change in MW and (M) over bar(w)/(M) over bar(n). This effect is not caused by decomposition or disproportionation of the binuclear titanocenes as evidenced by the stability of the catalyst.展开更多
The molecular structure of polyethylene (PE) samples with various comonomers including propylene, I-butane and 1-hexene was investigated by DSC and C-13-NMR techniques. The density of the samples varies from 0.948 g/c...The molecular structure of polyethylene (PE) samples with various comonomers including propylene, I-butane and 1-hexene was investigated by DSC and C-13-NMR techniques. The density of the samples varies from 0.948 g/cm(3) to 0.917 g/cm(3), and the molecular weight determined by the GPC method is in the range of 1 similar to2 x 10(5). The branch paint content of the samples was determined by C-13-NMR measurements and was found to be less than 20 per 1000 C atoms along the main chain. Crystallization segregation DSC technique (CSDSC) was used to characterize the branch point distribution or the segment length distribution of PEs. The crystallization segregation was performed in a successive annealing process at decreasing temperatures. The interval of two successive annealing temperatures was 6 K, and the time length of each annealing step was 2.5 h. The CSDSC results clearly indicate that all the PE samples used, including some metallocene PEs, more or less exhibit their non-uniformity in segment length distribution, and bimodal or multimodal CSDSC curves were usually observed. For quantitative characterization of the CSDSC curves and the segment length distribution two parameters, the average melting point, T-mAV, and the root-mean-square deviation of melting temperature, (DeltaT(m)(AV)(2))(1/2), were proposed. TmAV is corresponding to the average segment length due to branching and (DeltaT(m)(AV)(2))(1/2) gives information about the: width of the segment length distribution. Experimental results show that both the degree of average melting temperature depression and the width of the distribution seem to increase with increasing the branching content and are dependent on the type of comonomers. Very good reproducibility and additivity of the CSDSC method were evidenced experimentally. It was concluded that the CSDSC technique is a sensitive and convenient method for characterizing the segment length distribution of branched polyethylenes and will be of great interest in structure-property relationship studies of crystalline polymers.展开更多
A series of hydroxyl-terminated polyethylenes(HTPE)bearing various functional side groups(e.g.carboxyl,ester and butane groups)were synthesized by the combination of ring opening metathesis polymerization(ROMP)and vis...A series of hydroxyl-terminated polyethylenes(HTPE)bearing various functional side groups(e.g.carboxyl,ester and butane groups)were synthesized by the combination of ring opening metathesis polymerization(ROMP)and visible light photocatalytic thiol-ene reaction.The products are named as a,w-dihydroxyl-polyllpropionyloxythio)methinetrimethylene](HTPECarboxy),a,w dihydroxy-poly(methylpropionatethio)methinetrimethylene](HTPEeser)and a,wdihydroxyl-poly[(butylthio)methinetrimethylene](HTPEbutane)respectively.The investigation of ROMP indicated that the molecular weight of resultant hydroxy-terminated polybutadiene(HTPB)can be tailored by varying the feed ratios of monomer to chain transfer agent(CTA).The exploration of the photocatalytic thiol-ene reaction between HTPB precursor and methyl-3-mercaptopropionate revealed that blue light as well as oxygen accelerated the reaction.1H-NMR and 13C-NMR results verified all the double bonds in HTPB can be modified,and the main chain of resultant polymer can be considered as polyethylene.Subsequently,relationship between the structure of side groups and the thermal properties of functional PEs was studied.And the results suggested that the Tg was in the order of HTPEbuane<HTPEester<HTPEarboxy+.Greater interaction between side groups resulted in higher Tg.Moreover,all the functional PE samples exhibited poor thermostability as compared to HTPB.Finally,the promising applications for functional PEs were explored.HTPEcarboxy1 can be utilized as a smart material with pH-responsive properties due to its pH-dependent ionization of carboxyl side groups.HTPEbutane can be employed as a macro-initiator for building the triblock copolymer due to the presence of active hydroxyl end groups.HTPEester can serve as a plasticizer for PVC which can enhance the ductilityt of PVC without obviously sacrificing strength.展开更多
Cycloalkyl-modified 8-arylimino-5,6,7-trihydroquinolylnickel pre-catalysts,activated with either MAO or Et_(2)AlCl,are highly active for the polymerization of ethylene into branched polyethylene waxes with narrow poly...Cycloalkyl-modified 8-arylimino-5,6,7-trihydroquinolylnickel pre-catalysts,activated with either MAO or Et_(2)AlCl,are highly active for the polymerization of ethylene into branched polyethylene waxes with narrow polydispersity.展开更多
Solid-state NMR offers a unique way to monitor the local and collective chain motions in semi-crystalline polymers.In this review paper,we will briefly survey recent results on the solid-state NMR study of chain motio...Solid-state NMR offers a unique way to monitor the local and collective chain motions in semi-crystalline polymers.In this review paper,we will briefly survey recent results on the solid-state NMR study of chain motions in semi-crystalline polyethylenes(PEs).We will demonstrate that the state-of-the-art solid-state NMR now can provide very detailed knowledge about the local and collective chain motions in semi-crystalline PEs,which is of great relevance to our understanding of the mechanical behaviors of polyethylene in the microscopic level.展开更多
UHMWPE fibers exhibit impressive modulus and strength,but they have not reached their theoretical limits.Researchers focus on molecular weight,orientation,and crystallinity of UHMWPE,yet their contributions to mechani...UHMWPE fibers exhibit impressive modulus and strength,but they have not reached their theoretical limits.Researchers focus on molecular weight,orientation,and crystallinity of UHMWPE,yet their contributions to mechanical properties are unclear.Molecular dynamics simulations are valuable but often limited by computational constraints.Our aim is to simulate higher molecular weights to better represent real UHMWPE fibers.We used Packmol and Polyply methodologies to construct PE systems,with Polyply reproducing more reasonable properties of UHMWPE fibers.Additionally,tensile simulations showed that orientation and crystallinity greatly impact Young's modulus more than molecular weight.Energy decomposition indicated that higher molecular weights lead to covalent bonds that can withstand more energy during stretching,thus increasing breaking strength.Combining simulations with machine learning,we found that orientation has the most significant impact on Young's modulus,contributing 60%,and molecular weight plays the most crucial role in determining the breaking strength,accounting for 65%.This study provides a theoretical basis and guidelines for enhancing UHMWPE's modulus and strength.展开更多
Dynamic melt modification of polyethylene via the direct grafting of peroxide fragments shows promise for the development of processable functionalized materials.In this study,four linear low-density polyethylenes(LLD...Dynamic melt modification of polyethylene via the direct grafting of peroxide fragments shows promise for the development of processable functionalized materials.In this study,four linear low-density polyethylenes(LLDPEs)with comparable molecular weights but different short-chain branch(SCB)contents(ranging of 5-66 per 1000 carbon atoms)were modified via dynamic melt mixing using 2 wt% benzoyl peroxide at 145℃ and 50 r/min for 30 min.The influence of SCB content on the processability and structure of the resulting products was systematically investigated.All modified products exhibited good melt processability with melt flow rates(MFR)ranging from 0.46 g/10min to 1.07 g/10min.Products derived from low-SCB LLDPEs showed a lower MFR,higher cross-linking content,a larger number of long-chain branches,and a higher degree of benzoyl grafting.In contrast,those produced from high-SCB LLDPEs exhibited improved processability,reduced cross-linking,fewer long-chain branches,and lower benzoyl grafting levels.A detailed structural investigation of the soluble and insoluble fractions,which were separated using trichlorobenzene fractionation,was conducted to analyze the structural features of various modified products and demonstrate that the SCB content(i.e.,tertiary carbon density)significantly influences radical coupling during dynamic modification.Elevated tertiary carbon density,by introducing greater steric hindrance,suppresses radical coupling during dynamic modification,thereby reducing the efficiency of both crosslinking and peroxide fragment grafting.These findings provide new insights into the structure-reactivity relationships in peroxide-induced polyethylene modification and lay the foundation for tailoring material properties via dynamic processing.展开更多
Skin injury repair is a complicated process that involves wound healing.Effective wound dressings play a crucial role in enhancing this process by providing multiple functions,such as wettability,antibacterial activit...Skin injury repair is a complicated process that involves wound healing.Effective wound dressings play a crucial role in enhancing this process by providing multiple functions,such as wettability,antibacterial activity,and drug release.In this study,Calophyllum inophyllum oil(CIO)is incorporated into polyethylene oxide-polyvinyl acetate(PEO-PVAc)nanofibers using an electrospinning technique.The successful incorporation is verified by Fourier-transform infrared spectroscopy,while the morphology is observed by scanning electron microscopy.The fabricated nanofibers are beadless and have fiber diameter distributions of 333–472 nm.The addition of CIO significantly improves the wettability of the nanofibers,as indicated by a decrease in water contact angle,which is crucial for accelerating the healing process.Additionally,the CIO exhibits potent antibacterial activity against both Gram-positive(Escherichia coli)and Gram-negative(Staphylococcus aureus)bacteria,with expanding inhibition zones as the CIO concentration is increased.These findings highlight the great potential of PEO-PVAc/CIO nanofibers for advanced wound healing applications.展开更多
Catalysts are key for olefin polymerization reactions and are also ubiquitous in catalysis science.Multinuclear metal catalysts have witnessed enhanced performances in catalytic reactions relative to mononuclear catal...Catalysts are key for olefin polymerization reactions and are also ubiquitous in catalysis science.Multinuclear metal catalysts have witnessed enhanced performances in catalytic reactions relative to mononuclear catalysts,but which substantially involve multi-step,tedious,and difficult synthesis.Herein,this study reports an intriguing approach to construct multi-nuclear catalysts for the milestoneα-diimine nickel catalysts using an oligomeric strategy.A polymerizable norbornene unit is incorporated into theα-diimine ligand backbone,leading to the formation of the monomeric nickel catalyst Ni_(1)and its corresponding oligomeric nickel catalysts(Ni_(3)and Ni_(5))with varying degrees of polymerization(DP=3 and 5).Notably,the oligomeric catalyst Ni_(5)was facilely scaled up(50 g-level),showed enhanced thermal stability,exhibited 4.6 times higher activity,and yielded polyethylene elastomer with a 379%increased molecular weight in ethylene polymerization,compared to the monomeric catalyst Ni_(1).Catalytic performance enhancements of oligomeric catalysts were found to be DP-dependent.The kilogram-scale polyethylene,produced using Ni_(5)in a 20 L reactor,presented a highly branched all-hydrocarbon structure,which demonstrated typical elastic properties(tensile strength:4 MPa,elastic recovery:SR=72%)along with great processability(MFI=3.0 g/10 min),insulating characteristics(volume resistivity=2×10^(16)Ω/m),and hydrophobicity(water vapor permeability:0.03 g/m^(2)/day),suggesting potentially practical applications.展开更多
Heterogeneous polymerization represents a widely employed method in the polyolefin industry.In recent years,various heterogenization strategies for late transition metal catalysts have been developed,enabling effectiv...Heterogeneous polymerization represents a widely employed method in the polyolefin industry.In recent years,various heterogenization strategies for late transition metal catalysts have been developed,enabling effective control of polymer morphology and optimization of catalytic performance.However,while most studies have focused on designing anchoring groups and advancing support approaches,systematic investigations into how the support influences the catalytic behavior of the late transition metal catalysts.In this work,we fabricated supported α-diimine nickel catalysts by functionalizing the ligand with alkyl alcohol chains of varying lengths and supporting them onto MgCl_(2)supports.The ethylene polymerization behavior of these catalysts was then investigated.By precisely adjusting the alkyl alcohol chain length,the distance between the catalytically active metal center and the support surface was modulated.This approach demonstrates that support-induced steric hindrance effect can be effectively regulated by controlling the separation distance between the metal center and the support surface.展开更多
Pretreatment of Low-Density Polyethylene(LDPE)with physicochemical methods before biodegradation has been demonstrated as an effective strategy.The pretreatment of LDPE exhibited alterations in molecular structure,red...Pretreatment of Low-Density Polyethylene(LDPE)with physicochemical methods before biodegradation has been demonstrated as an effective strategy.The pretreatment of LDPE exhibited alterations in molecular structure,reducing hydrophobicity and decreasing tensile strength.Additionally,pretreating LDPE enhanced microbial biodegradability to improve biofilm formation and significantly reduced the physical weight of LDPE film.AS3–8 consortia exhibited a maximum weight loss of 8.0%±0.5%after 45 days of incubation.While Bacillus sp.AS3 and Sphingobacterium sp.AS8 demonstrated LDPE weight loss of 5.03%±1.6%and 1.6%±0.5%,respectively.The structure of LDPE was altered after incubation with the bacterial strains,resulting in a reduction in the intensity of functional groups,including C=O,C=C,N–H,and C–N.The carbonyl index(CI)of LDPE also decreased by 7.17%after the consortia AS3–8 degradation.Consortia AS3–8 significantly impacted the physical properties of LDPE by reducing the water contact angle(WCA),decreasing to 64.21°±3.69°,and tensile strength(TS),decreasing to 17.97±0.3 MPa.Moreover,the esterase activity was measured through 45 days of incubation.SDS-PAGE analysis of the AS3–8 consortia revealed bands at 35,48,and 70 kDa molecular weights,similar to known enzymes like laccase and esterase.Furthermore,SEM observations showed rough,cracked surfaces on pretreated LDPE,with biofilms present after incubation with the bacterial strains.GC–MS analysis revealed that AS3–8 consortia produced depolymerized chemicals,including alkanes,aldehydes,and esters.The LDPE biodegradation pathway was elucidated.This study addresses critical knowledge gaps in improving plastic degradation efficiency.展开更多
The intractable trade-off between proton conductivity and vanadium ion selectivity,known as the‘transmission paradox’is a critical bottleneck hindering the commercialization of vanadium flow batteries(VFBs).Inspired...The intractable trade-off between proton conductivity and vanadium ion selectivity,known as the‘transmission paradox’is a critical bottleneck hindering the commercialization of vanadium flow batteries(VFBs).Inspired by the multi-stage,synergistic filtration mechanism of the mammalian glomerular filtration barrier,a novel,biomimetic hierarchical composite membrane has been fabricated via a precise layer-by-layer strategy on a polyethylene(PE)substrate.This membrane integrates a polydopamine(PDA)adhesion layer,a sulfonated Zr-MOF ion-sieving layer,and a synergistic polybenzimidazole(PBI)matrix.Spectroscopic analysis confirmed the formation of a critical bifunctional acid-base interface(-SO_(3)^(−)…H^(+)N-)between the MOF and PBI,which densifies the structure and optimizes ion pathways.The resulting composite membrane exhibits excellent mechanical robustness,superior chemical stability,and exceptional dimensional stability.Most significantly,this architecture successfully decouples the performance trade-off,demonstrating both high proton conductivity(11.11 mS·cm^(-1))and remarkably suppressed vanadium ion permeability(2.4×10^(−8) cm^(2)·min^(-1)).This combination yields an outstanding ion selectivity of 46.29×10^(4) S·min·cm^(-3).When tested in a VFB single cell,the membrane enabled a high energy efficiency of 81.6%at 200 mA·cm^(-2),an ultra-long self-discharge time of 2700 min,and excellent long-term cycling stability.This biomimetic design strategy effectively resolves the core‘transmission paradox’offering a promising pathway for next-generation high-performance flow batteries.展开更多
Ultra-high molecular weight polyethylene(UHMWPE)is a key material for marine applications owing to its outstanding self-lubrication and corrosion resistance.However,its long-term performance is compromised by plastic ...Ultra-high molecular weight polyethylene(UHMWPE)is a key material for marine applications owing to its outstanding self-lubrication and corrosion resistance.However,its long-term performance is compromised by plastic deformation in seawater.In this study,we performed a comparative analysis of the UHMWPE dynamics under seawater and water conditions to investigate the plastic deformation of UHMWPE induced by seawater.The results show that the plastic deformation of UHMWPE is amplified in seawater relative to the water conditions.Under thin fluid conditions,frictional interfaces exhibit a higher interfacial friction force and interaction energy in seawater than in water.Compared to freely diffused water molecules,hydrated ions occupy larger interchain spaces within polyethylene.Furthermore,the diffusion of hydrated ions weakens the interchain interactions,promoting more severe polyethylene chain rearrangement and accelerating seawater-induced plastic deformation in UHMWPE during friction.Furthermore,the diffused seawater accelerated the disentangling of the polyethylene chains and enhanced the orderly orientation distribution of polyethylene.Compared to free water molecules,the water molecules of hydrated ions exhibit enhanced attraction to free-flowing water molecules,thereby accelerating seawater flow across submerged UHMWPE surfaces.This flow enhancement promotes surface polyethylene chain mobility in seawater.展开更多
The rapid decay of the surface wettability of plasma-treated polymers remains a critical limitation for their practical application in advanced materials.This study introduces a continuous atmospheric pressure plasma(...The rapid decay of the surface wettability of plasma-treated polymers remains a critical limitation for their practical application in advanced materials.This study introduces a continuous atmospheric pressure plasma(APP)technique for fabricating polyethylene(PE)separators with durable wettability,and elucidates the underlying mechanism.A systematic comparison of APP treatments with non-deposition and deposition gases,including Ar,Ar/O_(2),Ar/tetramethylcyclotetrasiloxane(TMCTS),and Ar/O_(2)/TMCTS,revealed the key impact factors in achieving durable wettability.Owing to the synergistic interactions of SiO_(x)C_(y)H_(z)nanoparticulate deposition,physical etching,and oxidative functionalization,the PE separator treated by Ar/O_(2)/TMCTS exhibited a 17.5-fold electrolyte wetting area compared to the original one.The improved surface energy and roughness of the SiO_(x)C_(y)H_(z)nanoparticle coating enhanced its electrochemical performance.The ionic conductivity increased by 1.9 times,while the charge transfer resistance decreased by 73.7%.Remarkably,owing to further oxidation of the SiO_(x)C_(y)H_(z)nanoparticle coating and the increase in its silica-like structure,the wetting area of the Ar/O_(2)/TMCTS-treated separator was still over 14-fold larger than that of the original separator after aging for 90 days.This study demonstrates an eco-friendly and scalable approach for fabricating high-performance battery separators and provides mechanistic insights into durable wettability by APP.展开更多
Polyethylene oxide(PEO)-based solid polymer electrolytes(SPEs)have long faced limitations due to low ionic conductivity at ambient temperature and poor interfacial stability with lithium metal anodes.Here,we present a...Polyethylene oxide(PEO)-based solid polymer electrolytes(SPEs)have long faced limitations due to low ionic conductivity at ambient temperature and poor interfacial stability with lithium metal anodes.Here,we present a structural engineering strategy to address these challenges through shear-induced crystallization of concentrated PEO-LiTFSI solutions,which self-assemble into flower-like spherulites with radially aligned lamellar crystals.This unique structure creates continuous Li^(+)transport highways through densely packed crystalline domains,achieving a record-high ionic conductivity of 1.70×10^(-4) S/cm at 25℃ for pristine PEO-based systems.Strategic incorporation of lithium montmorillonite(MMTli,10 wt%)further optimizes the composite electrolyte,balancing high ionic conductivity(1.47×10^(-4) S/cm)with enhanced electrochemical stability(4.99 V vs.Li^(+)/Li),elevated Li^(+)transference number(0.62),and mechanical robustness.The composite electrolyte enables stable Li plating/stripping over 800 h in symmetric Li||Li cells and powers LiFePO_(4)||Li solid-state batteries with 82%capacity retention after 200 cycles at 0.2 C under ambient conditions.This work pioneers a scalable processing paradigm for crystalline polymer electrolytes,offering new insights into ion transport mechanisms and validating clay minerals as multifunctional additives for next-generation energy storage systems.展开更多
Flexible materials play a crucial role in protecting against behind armour blunt trauma(BABT).However,their compliance complicates the understanding of failure mechanisms and energy absorption.This study used a combin...Flexible materials play a crucial role in protecting against behind armour blunt trauma(BABT).However,their compliance complicates the understanding of failure mechanisms and energy absorption.This study used a combined experimental and numerical approach to investigate the response and failure modes of a flexible ultra-high-molecular-weight polyethylene(UHMWPE)foam protective sandwich structure(UFPSS)under low-velocity impact(LVI).A finite element(FE)model,accounting for nonlinear large deformation and strain-rate-dependent material behavior,was developed for a woven-UFPSS(featuring a plain-woven fabric structure)subjected to a 50 J impact.Experimental and numerical results showed strong agreement in peak force(error<5%),maximum displacement(error<6%),and buffer time(error<8%).The impact's kinetic energy was mainly converted into internal energy of the fabric and foam materials(~50%),viscous dissipation in the foam core(12%-15%),frictional work at the contact interfaces(5%-6%),and work by the pneumatic fixture clamping force(~38%).This study provides the first investigation of the LVI performance of sandwich structures with all soft material layers,offering significant insights for the application of compliant materials in protective fields.展开更多
We have previously shown the success of polyethylene glycol fusion repair of segmental-loss peripheral nerve injuries in rats using freshly harvested,viable peripheral nerve allografts that can conduct action potentia...We have previously shown the success of polyethylene glycol fusion repair of segmental-loss peripheral nerve injuries in rats using freshly harvested,viable peripheral nerve allografts that can conduct action potentials.Because clinical application of polyethylene glycol fusion with viable peripheral nerve allografts demands pre-transplant donor tissue storage,we developed a protocol for ex vivo storage of rat sciatic nerves as viable peripheral nerve allografts,preserving many axons for up to 5 days.The current study evaluated the in vivo use of these stored viable peripheral nerve allografts.We hypothesized that stored viable peripheral nerve allografts with viable axons would enable successful in vivo repair of segmental-loss peripheral nerve injuries via polyethylene glycol-fusion.Polyethylene glycol-fused viable peripheral nerve allografts were classified as successful if they produced significantly improved locomotor recovery,as evaluated by the sciatic functional index,within 8 weeks post-repair.Many Sprague-Dawley and Lewis rats with successfully polyethylene glycol-fused viable peripheral nerve allografts had significantly improved sciatic functional index scores beginning at 5 weeks post-operatively.There was no significant difference in the efficiency and extent of successful polyethylene glycol fusion between stored and freshly harvested viable peripheral nerve allografts.In contrast,rats with non-fused negative control viable peripheral nerve allografts showed no recovery by 8 weeks post-operatively.Additional confirmatory outcome measures included in vivo compound action potentials and assessments of axon morphometry.These results suggest that viable peripheral nerve allografts can be stored and later used for successful polyethylene glycol fusion repair of segmental-loss peripheral nerve injuries.展开更多
Conventional polyethylene(PE)fibers face limitations in large-scale industrial applications due to their poor thermal stability and inherent hydrophobicity,which restrict processing temperatures and dyeability,especia...Conventional polyethylene(PE)fibers face limitations in large-scale industrial applications due to their poor thermal stability and inherent hydrophobicity,which restrict processing temperatures and dyeability,especially in blended fabric production.In this research,a one-step ultraviolet(UV)irradiation technology was employed to modify medium molecular weight PE fibers through simultaneous crosslinking and grafting modifications,aiming to enhance their thermal stability and hydrophilicity.The modification employed a cost-effective,UV-initiated crosslinking system consisting of benzophenone(BP)as the photoinitiator and triallyl isocyanurate(TAIC)as the cocrosslinker.Acrylic acid(AA)was selected as the grafting monomer.These modifiers were thoroughly mixed with the PE matrix in a liquid-phase environment,and the mixture was melt-spun into fibers.The resulting fibers were then subjected to UV irradiation,which triggered the crosslinking and grafting reactions.The effects of the mass fraction of each component and irradiation parameters on modification efficacy were systematically investigated,followed by a comprehensive characterization of the modified PE fibers.The modified PE fibers achieved optimal thermal stability under the following conditions:2.0%mass fractions for both BP and TAIC,a UV irradiation intensity of 2000 mW/cm^(2),and an equivalent irradiation time of 60 s.This synergistic modification approach enables the fibers to maintain superior morphological integrity and mechanical performance when exposed to elevated temperatures ranging from 130 to 150℃.Meanwhile,an AA grafting mass fraction of 2.0%maximizes hydrophilicity with minimal impact on other properties,as evidenced by a dramatic reduction in the water contact angle(WCA)from 105.0°(hydrophobic)to 48.4°(hydrophilic).These improvements confirm the effectiveness of the modification strategy in synergistically enhancing both thermal stability and hydrophilicity of PE fibers.展开更多
基金supported by the National Natural Science Foundation of China(No.U23B6011)the Jilin Provincial Science and Technology Department Program(No.20230101347JC)。
文摘Mechanochromic polyolefins represent a novel class of functionalized polyolefins,which still remains significant challenges.Pd(II)-catalyzed coordination-insertion copolymerization is a feasible method for achieving this kind of polymers,yet with linear microstructures.Ringopening metathesis polymerization(ROMP)offers another promising avenue for affording functionalized polyolefins.This method exhibits high polar group tolerance and the ability to precisely regulate polymer branches.In this study,we report the method for producing mechanochromic branched polyethylenes via ROMP.By employing the terpolymerization of a well-designed monomer containing the mechanochromic group,NB-ABF,with cyclooctene(COE)and long-chain 5-hexylcyclooctene(COE-C6),following by hydrogenation process,we synthesized a range of functionalized branched polyethylenes characterized by varied branching density and polar monomer incorporation.These polymers bear a structural resemblance to functionalized ethylene-octene copolymers.After crosslinking,mechanochromophores are generated,and mechanochromism is achieved in uniaxial tensile testing.A comprehensive assessment reveals that both the incorporation of polar monomers and variations in branching density significantly influence their mechanical properties.Notably,upon stretching,these materials display pronounced visible color change,confirming the successful development of mechanochromic branched polyethylenes.
文摘Short chain branching has been characterized using thermal fractionation, a stepwise isothermal crystallizationtechnique, followed by a melting analysis scan using differential scanning calorimetry. Short chain branching distributionwas also characterized by a continuous slow cooling crystallization, followed by a melting analysis scan. Four differentpolyethylenes were studied: Ziegler-Natta gas phase, Ziegler-Natta solution, metallocene, constrained-geometry single sitecatalyzed polyethylenes. The branching distribution was calculated from a calibration of branch content with meltingtemperature. The lamellar thickness was calculated based on the thermodynamic melting temperature of each polyethyleneand the surface free energy of the crystal face. The branching distribution and lamellar thickness distribution were used tocalculate weight average branch content, mean lamellar thickness, and a branch dispersity index. The results for the branchcontent were in good agreement with the known comonomer content of the polyethylenes. A limitation was that high branchcontent polyethylenes did not reach their potential crystallization at ambient temperatures. Cooling to sub-ambient wasnecessary to equilibrate the crystallization, but melting temperature versus branch content was not applicable after cooling tobelow ambient because the calibration data were not performed in this way.
文摘Seven new binuclear titanocenes with different linking bridges, unsubstituted or substituted on the Cp rings, were synthesized and tested for their effect on ethylene polymerization in the presence of MAO. The polyethylenes thus obtained had broad MWD or even bimodal GPC curves, as compared with that from two reference mononuclear titanocenes. This is explained by the difference in degree of steric hindrance around the active center sites imposed by the bulky substituted ligands assuming different configurations in the rotation of the catalyst molecules. Lower polymerization temperatures alleviate the effect of these configuration differences, as reflected in change in MW and (M) over bar(w)/(M) over bar(n). This effect is not caused by decomposition or disproportionation of the binuclear titanocenes as evidenced by the stability of the catalyst.
基金This work was supported by the Science Foundation of Polymer Physics Laboratory, Chinese Academy of Sciences.
文摘The molecular structure of polyethylene (PE) samples with various comonomers including propylene, I-butane and 1-hexene was investigated by DSC and C-13-NMR techniques. The density of the samples varies from 0.948 g/cm(3) to 0.917 g/cm(3), and the molecular weight determined by the GPC method is in the range of 1 similar to2 x 10(5). The branch paint content of the samples was determined by C-13-NMR measurements and was found to be less than 20 per 1000 C atoms along the main chain. Crystallization segregation DSC technique (CSDSC) was used to characterize the branch point distribution or the segment length distribution of PEs. The crystallization segregation was performed in a successive annealing process at decreasing temperatures. The interval of two successive annealing temperatures was 6 K, and the time length of each annealing step was 2.5 h. The CSDSC results clearly indicate that all the PE samples used, including some metallocene PEs, more or less exhibit their non-uniformity in segment length distribution, and bimodal or multimodal CSDSC curves were usually observed. For quantitative characterization of the CSDSC curves and the segment length distribution two parameters, the average melting point, T-mAV, and the root-mean-square deviation of melting temperature, (DeltaT(m)(AV)(2))(1/2), were proposed. TmAV is corresponding to the average segment length due to branching and (DeltaT(m)(AV)(2))(1/2) gives information about the: width of the segment length distribution. Experimental results show that both the degree of average melting temperature depression and the width of the distribution seem to increase with increasing the branching content and are dependent on the type of comonomers. Very good reproducibility and additivity of the CSDSC method were evidenced experimentally. It was concluded that the CSDSC technique is a sensitive and convenient method for characterizing the segment length distribution of branched polyethylenes and will be of great interest in structure-property relationship studies of crystalline polymers.
基金the financial support from the National Natural Science Foundation of China(Nos.51803111,31670596 and 11904220)the Natural Science Foundation of Shaanxi province(Nos.2019JQ-786 and 2020GY-232).
文摘A series of hydroxyl-terminated polyethylenes(HTPE)bearing various functional side groups(e.g.carboxyl,ester and butane groups)were synthesized by the combination of ring opening metathesis polymerization(ROMP)and visible light photocatalytic thiol-ene reaction.The products are named as a,w-dihydroxyl-polyllpropionyloxythio)methinetrimethylene](HTPECarboxy),a,w dihydroxy-poly(methylpropionatethio)methinetrimethylene](HTPEeser)and a,wdihydroxyl-poly[(butylthio)methinetrimethylene](HTPEbutane)respectively.The investigation of ROMP indicated that the molecular weight of resultant hydroxy-terminated polybutadiene(HTPB)can be tailored by varying the feed ratios of monomer to chain transfer agent(CTA).The exploration of the photocatalytic thiol-ene reaction between HTPB precursor and methyl-3-mercaptopropionate revealed that blue light as well as oxygen accelerated the reaction.1H-NMR and 13C-NMR results verified all the double bonds in HTPB can be modified,and the main chain of resultant polymer can be considered as polyethylene.Subsequently,relationship between the structure of side groups and the thermal properties of functional PEs was studied.And the results suggested that the Tg was in the order of HTPEbuane<HTPEester<HTPEarboxy+.Greater interaction between side groups resulted in higher Tg.Moreover,all the functional PE samples exhibited poor thermostability as compared to HTPB.Finally,the promising applications for functional PEs were explored.HTPEcarboxy1 can be utilized as a smart material with pH-responsive properties due to its pH-dependent ionization of carboxyl side groups.HTPEbutane can be employed as a macro-initiator for building the triblock copolymer due to the presence of active hydroxyl end groups.HTPEester can serve as a plasticizer for PVC which can enhance the ductilityt of PVC without obviously sacrificing strength.
基金supported by the NSFC(No.21374123,51411130208 and U1362204).
文摘Cycloalkyl-modified 8-arylimino-5,6,7-trihydroquinolylnickel pre-catalysts,activated with either MAO or Et_(2)AlCl,are highly active for the polymerization of ethylene into branched polyethylene waxes with narrow polydispersity.
基金The National Natural Science Foundation of China(21174039)
文摘Solid-state NMR offers a unique way to monitor the local and collective chain motions in semi-crystalline polymers.In this review paper,we will briefly survey recent results on the solid-state NMR study of chain motions in semi-crystalline polyethylenes(PEs).We will demonstrate that the state-of-the-art solid-state NMR now can provide very detailed knowledge about the local and collective chain motions in semi-crystalline PEs,which is of great relevance to our understanding of the mechanical behaviors of polyethylene in the microscopic level.
基金financially supported by the National Natural Science Foundation of China(Nos.52303298 and 52233002)。
文摘UHMWPE fibers exhibit impressive modulus and strength,but they have not reached their theoretical limits.Researchers focus on molecular weight,orientation,and crystallinity of UHMWPE,yet their contributions to mechanical properties are unclear.Molecular dynamics simulations are valuable but often limited by computational constraints.Our aim is to simulate higher molecular weights to better represent real UHMWPE fibers.We used Packmol and Polyply methodologies to construct PE systems,with Polyply reproducing more reasonable properties of UHMWPE fibers.Additionally,tensile simulations showed that orientation and crystallinity greatly impact Young's modulus more than molecular weight.Energy decomposition indicated that higher molecular weights lead to covalent bonds that can withstand more energy during stretching,thus increasing breaking strength.Combining simulations with machine learning,we found that orientation has the most significant impact on Young's modulus,contributing 60%,and molecular weight plays the most crucial role in determining the breaking strength,accounting for 65%.This study provides a theoretical basis and guidelines for enhancing UHMWPE's modulus and strength.
基金financially supported by the Science and Technology Project of PetroChina Company Limited,China(No.2022DJ6314)the National Natural Science Foundation of China(No.52173056)。
文摘Dynamic melt modification of polyethylene via the direct grafting of peroxide fragments shows promise for the development of processable functionalized materials.In this study,four linear low-density polyethylenes(LLDPEs)with comparable molecular weights but different short-chain branch(SCB)contents(ranging of 5-66 per 1000 carbon atoms)were modified via dynamic melt mixing using 2 wt% benzoyl peroxide at 145℃ and 50 r/min for 30 min.The influence of SCB content on the processability and structure of the resulting products was systematically investigated.All modified products exhibited good melt processability with melt flow rates(MFR)ranging from 0.46 g/10min to 1.07 g/10min.Products derived from low-SCB LLDPEs showed a lower MFR,higher cross-linking content,a larger number of long-chain branches,and a higher degree of benzoyl grafting.In contrast,those produced from high-SCB LLDPEs exhibited improved processability,reduced cross-linking,fewer long-chain branches,and lower benzoyl grafting levels.A detailed structural investigation of the soluble and insoluble fractions,which were separated using trichlorobenzene fractionation,was conducted to analyze the structural features of various modified products and demonstrate that the SCB content(i.e.,tertiary carbon density)significantly influences radical coupling during dynamic modification.Elevated tertiary carbon density,by introducing greater steric hindrance,suppresses radical coupling during dynamic modification,thereby reducing the efficiency of both crosslinking and peroxide fragment grafting.These findings provide new insights into the structure-reactivity relationships in peroxide-induced polyethylene modification and lay the foundation for tailoring material properties via dynamic processing.
基金funded by Rekognisi Tugas Akhir(RTA)program(Contract No.5286/UN1.P1/PT.01.03/2024)supported by Universitas Gadjah Mada,Indonesia.
文摘Skin injury repair is a complicated process that involves wound healing.Effective wound dressings play a crucial role in enhancing this process by providing multiple functions,such as wettability,antibacterial activity,and drug release.In this study,Calophyllum inophyllum oil(CIO)is incorporated into polyethylene oxide-polyvinyl acetate(PEO-PVAc)nanofibers using an electrospinning technique.The successful incorporation is verified by Fourier-transform infrared spectroscopy,while the morphology is observed by scanning electron microscopy.The fabricated nanofibers are beadless and have fiber diameter distributions of 333–472 nm.The addition of CIO significantly improves the wettability of the nanofibers,as indicated by a decrease in water contact angle,which is crucial for accelerating the healing process.Additionally,the CIO exhibits potent antibacterial activity against both Gram-positive(Escherichia coli)and Gram-negative(Staphylococcus aureus)bacteria,with expanding inhibition zones as the CIO concentration is increased.These findings highlight the great potential of PEO-PVAc/CIO nanofibers for advanced wound healing applications.
基金financial support from the National Natural Science Foundation of China(Nos.22401274,U23B6011)the Jilin Provincial Science and Technology Department Program(No.20250102070JC)。
文摘Catalysts are key for olefin polymerization reactions and are also ubiquitous in catalysis science.Multinuclear metal catalysts have witnessed enhanced performances in catalytic reactions relative to mononuclear catalysts,but which substantially involve multi-step,tedious,and difficult synthesis.Herein,this study reports an intriguing approach to construct multi-nuclear catalysts for the milestoneα-diimine nickel catalysts using an oligomeric strategy.A polymerizable norbornene unit is incorporated into theα-diimine ligand backbone,leading to the formation of the monomeric nickel catalyst Ni_(1)and its corresponding oligomeric nickel catalysts(Ni_(3)and Ni_(5))with varying degrees of polymerization(DP=3 and 5).Notably,the oligomeric catalyst Ni_(5)was facilely scaled up(50 g-level),showed enhanced thermal stability,exhibited 4.6 times higher activity,and yielded polyethylene elastomer with a 379%increased molecular weight in ethylene polymerization,compared to the monomeric catalyst Ni_(1).Catalytic performance enhancements of oligomeric catalysts were found to be DP-dependent.The kilogram-scale polyethylene,produced using Ni_(5)in a 20 L reactor,presented a highly branched all-hydrocarbon structure,which demonstrated typical elastic properties(tensile strength:4 MPa,elastic recovery:SR=72%)along with great processability(MFI=3.0 g/10 min),insulating characteristics(volume resistivity=2×10^(16)Ω/m),and hydrophobicity(water vapor permeability:0.03 g/m^(2)/day),suggesting potentially practical applications.
基金financially supported by the National Natural Science Foundation of China(No.52473338)the National Natural Science Foundation of China(Nos.52173004 and 51873055)+3 种基金Strategic Priority Research Program of the Chinese Academy of Sciences(No.XDA0540000)Advanced Materials-National Science and Technology Major Project(No.2025ZD0614000)Hebei Natural Science Foundation(No.E2022202015)Anhui Province Science and Technology Innovation Tackling Key Project(No.202423i08050025)。
文摘Heterogeneous polymerization represents a widely employed method in the polyolefin industry.In recent years,various heterogenization strategies for late transition metal catalysts have been developed,enabling effective control of polymer morphology and optimization of catalytic performance.However,while most studies have focused on designing anchoring groups and advancing support approaches,systematic investigations into how the support influences the catalytic behavior of the late transition metal catalysts.In this work,we fabricated supported α-diimine nickel catalysts by functionalizing the ligand with alkyl alcohol chains of varying lengths and supporting them onto MgCl_(2)supports.The ethylene polymerization behavior of these catalysts was then investigated.By precisely adjusting the alkyl alcohol chain length,the distance between the catalytically active metal center and the support surface was modulated.This approach demonstrates that support-induced steric hindrance effect can be effectively regulated by controlling the separation distance between the metal center and the support surface.
文摘Pretreatment of Low-Density Polyethylene(LDPE)with physicochemical methods before biodegradation has been demonstrated as an effective strategy.The pretreatment of LDPE exhibited alterations in molecular structure,reducing hydrophobicity and decreasing tensile strength.Additionally,pretreating LDPE enhanced microbial biodegradability to improve biofilm formation and significantly reduced the physical weight of LDPE film.AS3–8 consortia exhibited a maximum weight loss of 8.0%±0.5%after 45 days of incubation.While Bacillus sp.AS3 and Sphingobacterium sp.AS8 demonstrated LDPE weight loss of 5.03%±1.6%and 1.6%±0.5%,respectively.The structure of LDPE was altered after incubation with the bacterial strains,resulting in a reduction in the intensity of functional groups,including C=O,C=C,N–H,and C–N.The carbonyl index(CI)of LDPE also decreased by 7.17%after the consortia AS3–8 degradation.Consortia AS3–8 significantly impacted the physical properties of LDPE by reducing the water contact angle(WCA),decreasing to 64.21°±3.69°,and tensile strength(TS),decreasing to 17.97±0.3 MPa.Moreover,the esterase activity was measured through 45 days of incubation.SDS-PAGE analysis of the AS3–8 consortia revealed bands at 35,48,and 70 kDa molecular weights,similar to known enzymes like laccase and esterase.Furthermore,SEM observations showed rough,cracked surfaces on pretreated LDPE,with biofilms present after incubation with the bacterial strains.GC–MS analysis revealed that AS3–8 consortia produced depolymerized chemicals,including alkanes,aldehydes,and esters.The LDPE biodegradation pathway was elucidated.This study addresses critical knowledge gaps in improving plastic degradation efficiency.
基金supported by the Natural Science Foundation of Liaoning Province(Grant Nos:2025-BSLH-247,2025-BSLH-246)Liaoning Provincial Department of Education Foundation(Grant Nos:LJ212410148012,LJ242510148002)+1 种基金Inner Mongolia’s Key R&D and Achievement Industrialization Program(Grant No:2025YFHH0017)China Postdoctoral Science Foundation(Grant Nos:2025MD774148,2025M770082).
文摘The intractable trade-off between proton conductivity and vanadium ion selectivity,known as the‘transmission paradox’is a critical bottleneck hindering the commercialization of vanadium flow batteries(VFBs).Inspired by the multi-stage,synergistic filtration mechanism of the mammalian glomerular filtration barrier,a novel,biomimetic hierarchical composite membrane has been fabricated via a precise layer-by-layer strategy on a polyethylene(PE)substrate.This membrane integrates a polydopamine(PDA)adhesion layer,a sulfonated Zr-MOF ion-sieving layer,and a synergistic polybenzimidazole(PBI)matrix.Spectroscopic analysis confirmed the formation of a critical bifunctional acid-base interface(-SO_(3)^(−)…H^(+)N-)between the MOF and PBI,which densifies the structure and optimizes ion pathways.The resulting composite membrane exhibits excellent mechanical robustness,superior chemical stability,and exceptional dimensional stability.Most significantly,this architecture successfully decouples the performance trade-off,demonstrating both high proton conductivity(11.11 mS·cm^(-1))and remarkably suppressed vanadium ion permeability(2.4×10^(−8) cm^(2)·min^(-1)).This combination yields an outstanding ion selectivity of 46.29×10^(4) S·min·cm^(-3).When tested in a VFB single cell,the membrane enabled a high energy efficiency of 81.6%at 200 mA·cm^(-2),an ultra-long self-discharge time of 2700 min,and excellent long-term cycling stability.This biomimetic design strategy effectively resolves the core‘transmission paradox’offering a promising pathway for next-generation high-performance flow batteries.
基金financially supported by the National Natural Science Foundation of China(Nos.51909023 and 51775077)the Natural Science Foundation of Liaoning Province(No.2021-MS-140)the Fundamental Research Funds for the Central Universities(No.3132025114)。
文摘Ultra-high molecular weight polyethylene(UHMWPE)is a key material for marine applications owing to its outstanding self-lubrication and corrosion resistance.However,its long-term performance is compromised by plastic deformation in seawater.In this study,we performed a comparative analysis of the UHMWPE dynamics under seawater and water conditions to investigate the plastic deformation of UHMWPE induced by seawater.The results show that the plastic deformation of UHMWPE is amplified in seawater relative to the water conditions.Under thin fluid conditions,frictional interfaces exhibit a higher interfacial friction force and interaction energy in seawater than in water.Compared to freely diffused water molecules,hydrated ions occupy larger interchain spaces within polyethylene.Furthermore,the diffusion of hydrated ions weakens the interchain interactions,promoting more severe polyethylene chain rearrangement and accelerating seawater-induced plastic deformation in UHMWPE during friction.Furthermore,the diffused seawater accelerated the disentangling of the polyethylene chains and enhanced the orderly orientation distribution of polyethylene.Compared to free water molecules,the water molecules of hydrated ions exhibit enhanced attraction to free-flowing water molecules,thereby accelerating seawater flow across submerged UHMWPE surfaces.This flow enhancement promotes surface polyethylene chain mobility in seawater.
基金supported by the National Natural Science Foundation of China(No.12075054)the Fundamental Research Funds for the Central Universities(No.CUSF-DH-T-2024069)。
文摘The rapid decay of the surface wettability of plasma-treated polymers remains a critical limitation for their practical application in advanced materials.This study introduces a continuous atmospheric pressure plasma(APP)technique for fabricating polyethylene(PE)separators with durable wettability,and elucidates the underlying mechanism.A systematic comparison of APP treatments with non-deposition and deposition gases,including Ar,Ar/O_(2),Ar/tetramethylcyclotetrasiloxane(TMCTS),and Ar/O_(2)/TMCTS,revealed the key impact factors in achieving durable wettability.Owing to the synergistic interactions of SiO_(x)C_(y)H_(z)nanoparticulate deposition,physical etching,and oxidative functionalization,the PE separator treated by Ar/O_(2)/TMCTS exhibited a 17.5-fold electrolyte wetting area compared to the original one.The improved surface energy and roughness of the SiO_(x)C_(y)H_(z)nanoparticle coating enhanced its electrochemical performance.The ionic conductivity increased by 1.9 times,while the charge transfer resistance decreased by 73.7%.Remarkably,owing to further oxidation of the SiO_(x)C_(y)H_(z)nanoparticle coating and the increase in its silica-like structure,the wetting area of the Ar/O_(2)/TMCTS-treated separator was still over 14-fold larger than that of the original separator after aging for 90 days.This study demonstrates an eco-friendly and scalable approach for fabricating high-performance battery separators and provides mechanistic insights into durable wettability by APP.
基金supported by the National Natural Science Foundation of China(No.42272044)the High-performance Computing Platform of China University of Geosciences Beijing。
文摘Polyethylene oxide(PEO)-based solid polymer electrolytes(SPEs)have long faced limitations due to low ionic conductivity at ambient temperature and poor interfacial stability with lithium metal anodes.Here,we present a structural engineering strategy to address these challenges through shear-induced crystallization of concentrated PEO-LiTFSI solutions,which self-assemble into flower-like spherulites with radially aligned lamellar crystals.This unique structure creates continuous Li^(+)transport highways through densely packed crystalline domains,achieving a record-high ionic conductivity of 1.70×10^(-4) S/cm at 25℃ for pristine PEO-based systems.Strategic incorporation of lithium montmorillonite(MMTli,10 wt%)further optimizes the composite electrolyte,balancing high ionic conductivity(1.47×10^(-4) S/cm)with enhanced electrochemical stability(4.99 V vs.Li^(+)/Li),elevated Li^(+)transference number(0.62),and mechanical robustness.The composite electrolyte enables stable Li plating/stripping over 800 h in symmetric Li||Li cells and powers LiFePO_(4)||Li solid-state batteries with 82%capacity retention after 200 cycles at 0.2 C under ambient conditions.This work pioneers a scalable processing paradigm for crystalline polymer electrolytes,offering new insights into ion transport mechanisms and validating clay minerals as multifunctional additives for next-generation energy storage systems.
基金supported by the Zhenjiang Key R&D Plan(GY2021009)Lianyungang City Major Technology Breakthrough(CGJBGS2104)+2 种基金National Natural Science Foundation of China under Grant(12302456)National Key Laboratory Foundation of Science and Technology on Materials under Shock and Impact under Grant(6142902241601)China Postdoctoral Science Foundation under Grants(2025M774217)。
文摘Flexible materials play a crucial role in protecting against behind armour blunt trauma(BABT).However,their compliance complicates the understanding of failure mechanisms and energy absorption.This study used a combined experimental and numerical approach to investigate the response and failure modes of a flexible ultra-high-molecular-weight polyethylene(UHMWPE)foam protective sandwich structure(UFPSS)under low-velocity impact(LVI).A finite element(FE)model,accounting for nonlinear large deformation and strain-rate-dependent material behavior,was developed for a woven-UFPSS(featuring a plain-woven fabric structure)subjected to a 50 J impact.Experimental and numerical results showed strong agreement in peak force(error<5%),maximum displacement(error<6%),and buffer time(error<8%).The impact's kinetic energy was mainly converted into internal energy of the fabric and foam materials(~50%),viscous dissipation in the foam core(12%-15%),frictional work at the contact interfaces(5%-6%),and work by the pneumatic fixture clamping force(~38%).This study provides the first investigation of the LVI performance of sandwich structures with all soft material layers,offering significant insights for the application of compliant materials in protective fields.
基金National Institutes of Health(NIH)R01-NS128086 grant(to GDB and JSB)Lone Star Paralysis Foundation(to GDB).
文摘We have previously shown the success of polyethylene glycol fusion repair of segmental-loss peripheral nerve injuries in rats using freshly harvested,viable peripheral nerve allografts that can conduct action potentials.Because clinical application of polyethylene glycol fusion with viable peripheral nerve allografts demands pre-transplant donor tissue storage,we developed a protocol for ex vivo storage of rat sciatic nerves as viable peripheral nerve allografts,preserving many axons for up to 5 days.The current study evaluated the in vivo use of these stored viable peripheral nerve allografts.We hypothesized that stored viable peripheral nerve allografts with viable axons would enable successful in vivo repair of segmental-loss peripheral nerve injuries via polyethylene glycol-fusion.Polyethylene glycol-fused viable peripheral nerve allografts were classified as successful if they produced significantly improved locomotor recovery,as evaluated by the sciatic functional index,within 8 weeks post-repair.Many Sprague-Dawley and Lewis rats with successfully polyethylene glycol-fused viable peripheral nerve allografts had significantly improved sciatic functional index scores beginning at 5 weeks post-operatively.There was no significant difference in the efficiency and extent of successful polyethylene glycol fusion between stored and freshly harvested viable peripheral nerve allografts.In contrast,rats with non-fused negative control viable peripheral nerve allografts showed no recovery by 8 weeks post-operatively.Additional confirmatory outcome measures included in vivo compound action potentials and assessments of axon morphometry.These results suggest that viable peripheral nerve allografts can be stored and later used for successful polyethylene glycol fusion repair of segmental-loss peripheral nerve injuries.
文摘Conventional polyethylene(PE)fibers face limitations in large-scale industrial applications due to their poor thermal stability and inherent hydrophobicity,which restrict processing temperatures and dyeability,especially in blended fabric production.In this research,a one-step ultraviolet(UV)irradiation technology was employed to modify medium molecular weight PE fibers through simultaneous crosslinking and grafting modifications,aiming to enhance their thermal stability and hydrophilicity.The modification employed a cost-effective,UV-initiated crosslinking system consisting of benzophenone(BP)as the photoinitiator and triallyl isocyanurate(TAIC)as the cocrosslinker.Acrylic acid(AA)was selected as the grafting monomer.These modifiers were thoroughly mixed with the PE matrix in a liquid-phase environment,and the mixture was melt-spun into fibers.The resulting fibers were then subjected to UV irradiation,which triggered the crosslinking and grafting reactions.The effects of the mass fraction of each component and irradiation parameters on modification efficacy were systematically investigated,followed by a comprehensive characterization of the modified PE fibers.The modified PE fibers achieved optimal thermal stability under the following conditions:2.0%mass fractions for both BP and TAIC,a UV irradiation intensity of 2000 mW/cm^(2),and an equivalent irradiation time of 60 s.This synergistic modification approach enables the fibers to maintain superior morphological integrity and mechanical performance when exposed to elevated temperatures ranging from 130 to 150℃.Meanwhile,an AA grafting mass fraction of 2.0%maximizes hydrophilicity with minimal impact on other properties,as evidenced by a dramatic reduction in the water contact angle(WCA)from 105.0°(hydrophobic)to 48.4°(hydrophilic).These improvements confirm the effectiveness of the modification strategy in synergistically enhancing both thermal stability and hydrophilicity of PE fibers.
