Azobenzene-based polymer actuators show great promise for photoactuation owing to their unique photoisomerization behavior and tailorable molecular programmability.However,conventional systems are limited by inadequat...Azobenzene-based polymer actuators show great promise for photoactuation owing to their unique photoisomerization behavior and tailorable molecular programmability.However,conventional systems are limited by inadequate mechanical robustness,self-healing,and recyclability,hindering their practical implementation.Herein,we present a high-performance azobenzene-functionalized polyurethane(AzoPU)elastomer actuator designed via molecular engineering of photoactive azobenzene moieties and dynamic disulfide bonds.AzoPU exhibits exceptional mechanical properties with retained performance after multiple reshaping cycles,enabled by well-engineered hard-soft segments and synergistic stress dissipation from weak covalent bonds/hierarchical hydrogen bonds.It achieves over 93%self-healing efficiency at room temperature owing to the synergistic interplay of disulfide bonds in the polymer backbone and intermolecular hydrogen bonds.Furthermore,it demonstrates remarkable light-triggered actuation behavior,achieving a phototropic bending angle exceeding 180°toward the light source within 45 s.To showcase its practical potential,proof-of-concept photoactuated devices with flower-,hook-,and gripper-like and local-orientation processed strip-shaped structures were fabricated,which exhibited rapid and reversible light-triggered deformation.This study proposes a novel strategy for the development of intelligent polymeric materials that integrate light responsiveness,self-healing,and recyclability,thus holding great promise for applications in flexible electronics,smart actuators,and sustainable functional materials.展开更多
Reuse/recycling of expensive components in next-generation optoelectronic systems(e.g.,flexible electronics and foldable displays)for sustainability purposes impose stringent requirements on optically clear adhesive(O...Reuse/recycling of expensive components in next-generation optoelectronic systems(e.g.,flexible electronics and foldable displays)for sustainability purposes impose stringent requirements on optically clear adhesive(OCA)with on-demand adhesion/deadhesion capability.Although some hot-melt OCAs have been developed,there still remain great challenges in balancing the mechanical property,adhesion/detachment and recyclability/reusability of the OCAs.Herein,we developed a debondable and robust polyurethane(PU)-based optically clear adhesive with both mechanical and chemical recyclability,overcoming the critical bottlenecks in sustainable advanced manufacturing.The ductile yet strong PU-based OCAs not only can adhere to various optically transparent glass and polymeric substrates(with a bonding strength high up to 5.0 MPa),but also exhibit deadhesion capability at high temperature owing to the thermally sensitive H-bonding interaction within the polymer network.The ondemand adhesion/deadhesion facilitates non-destructive detachment of functional assemblies and materials recycling/repair.The mechanical and chemical recyclability of PU-based OCAs can also effectively reduce the cost and address the endof-life issues.Moreover,the PU-based OCAs outperformed some commercial optical adhesives.In view of the straightforward synthesis,easy industrial scale-up and exceptional comprehensive properties,the PU-based OCAs will provide promising transformative solutions for advancing the circular economy and sustainability in next-generation optoelectronic devices.展开更多
The development of substitutable meniscus implants that can effectively protect articular cartilage remains a great challenge.Herein,a polyurethane with chemical crosslinking and sulfobetaine extenders containing hydr...The development of substitutable meniscus implants that can effectively protect articular cartilage remains a great challenge.Herein,a polyurethane with chemical crosslinking and sulfobetaine extenders containing hydrophobic chains(PU-CL-hSB)is developed,which could improve comprehensive properties and long-term stability simultaneously.By regulating the mole ratio of functional groups,PU-CL-hSB with appropriate mechanical properties,excellent tribological properties,and good fatigue resistance is used to prepare substitutable meniscus implant by hot-pressing.Due to the synergistic effect of functional groups,PU-CL-hSB meniscus implant presents comparable or even superior properties to native meniscus.It withstands a maximum force of 26.08 N versus 25.14 N for native meniscus,an energy dissipation from 45.93 to 39.17 N mm compared to 28.83 to 19.11 N mm for native meniscus over 300 cycles,and a friction coefficient from 0.08 to 0.19 compared to 0.11 to 0.26 for native meniscus.This PU-CL-hSB meniscus implant is further implanted into live rabbit knee joints for 8 and 25 weeks by a new approach,and in vivo data indicate that PU-CL-hSB meniscus implant not only protects articular cartilage from severe damage without eliciting inflammatory responses,but also can maintain normal physiological activities in the native state.Our findings present a substitutable meniscus implant that could be applied in vivo and propose evaluation methodologies for meniscus implants.展开更多
Background:The development of materials for cardiovascular surgery that would improve the effectiveness of surgical interventions remains an important task.Surgical intervention during the implantation of vascular pro...Background:The development of materials for cardiovascular surgery that would improve the effectiveness of surgical interventions remains an important task.Surgical intervention during the implantation of vascular prostheses and stents,and the body’s reaction to artificial materials,could lead to chronic inflammation,a local increase in the concentration of proinflammatory factors,and stimulation of unwanted tissue growth.The introduction of nonsteroidal anti-inflammatory drugs into implantable devices could be used to obtain vascular implants that do not induce inflammation and do not induce neointimal tissue outgrowth.Methods:The scaffolds were made by electrospinning from mixtures of polyurethane(PU)with diclofenac(DF).The kinetics of DF release from the scaffolds composed of 3%PU/10%HSA/3%DMSO/DF and 3%PU/DF were studied.The biocompatibility and anti-inflammatory effects of the obtained scaffolds on human gingival fibroblasts and umbilical vein endothelial cells were studied.Results:Both types of scaffolds are characterized by fast DF release.The viability of cells cultured on scaffolds is 2 times worse than that of cells cultured on plastic.The level of the proinflammatory cytokine IL-6 in the culture medium of cells cultured on DF-containing scaffolds was lower than that of cells cultured on scaffolds without DF.Conclusion:The introduction of DF into scaffolds minimizes the inflammation caused by cell reactions to an artificial material.展开更多
Polyurethane elastomers exhibit high dielectric constants owing to their polar groups,and can be used as energy storage capacitors.Energy storage depends not only on the dielectric constant but also on the dielectric ...Polyurethane elastomers exhibit high dielectric constants owing to their polar groups,and can be used as energy storage capacitors.Energy storage depends not only on the dielectric constant but also on the dielectric loss.However,the relationship between chain structure and dielectric properties is not yet clear.Ketal-containing crosslinked polyurethane elastomers were prepared using cyclic ketal diol as a chain extender.The effect of the soft segment length on the dielectric properties and energy storage was investigated.The cause of the change in the dipolar polarization with the soft segment length was analyzed.As the soft segment length increased,the hard-soft hydrogen bonding decreased,whereas the hard-hard hydrogen bonding increased.Under the action of an electric field,the polar bonds in the ketal-containing polyurethane elastomer overcome the hydrogen bonding between hard-soft segments to produce polarization;meanwhile,they also experience crankshaft motions to generate polarization.The former has a relatively high relaxation activation energy of approximately 10-20 k J·mol^(-1),resulting in a large dielectric loss.The latter has a relatively low relaxation activation energy,approximately 0.7-1.7 kJ·mol^(-1),leading to low dielectric loss.As a result,the dielectric constant showed a decreasing trend,and the dielectric loss gradually decreased.This study provides a theoretical foundation for improving the dielectric properties of polyurethane elastomers.展开更多
The development of intrinsically conductive piezoresistive sensors with high strain tolerance has garnered significant interest.While elastomeric polymers exhibit excellent strain capabilities,their utility in sensing...The development of intrinsically conductive piezoresistive sensors with high strain tolerance has garnered significant interest.While elastomeric polymers exhibit excellent strain capabilities,their utility in sensing applications has been limited by inherent challenges such as high electrical resistivity,poor aging resistance,and interfacial incompatibility.To address these limitations,hydroxyl-terminated polybutadiene(HTPB)-based polyurethane was chemically modified with acetylferrocene-polyaniline conductive moieties to enhance charge transport properties.Remarkably,this covalent functionalization endowed the resulting ferrocene-polyaniline hybrid polyurethane(FPHP)with a conductivity of2.33 n A at 1 V bias while preserving piezoresistive functionality.The FPHP demonstrated exceptional mechanical-electrical performance,achieving 254% elongation at break with strain-dependent gauge factors of 7.28(0%-12.5% strain,R^(2)=0.9504)and 19.66(12.5%-35.0% strain,R^(2)=0.9929).Further characterization revealed a rapid 0.60 s response time and stability over 3500 strain-release cycles at compression strain,underscoring its durability under repetitive loading.The FPHP sensor was capable of monitoring various human movements and recognizing writing signals.These advances establish a materials design paradigm for fabricating flexible sensors that synergistically integrate high deformability,tunable sensitivity,and robust operational stability,positioning FPHP as a promising candidate for next-generation wearable electronics and soft robotics.展开更多
Pyrolysis technology has emerged as a promising method for converting waste polyurethane(WPU)from waste refrigerators into high-value chemicals.In this study,the copper(Cu)-assisted pyrolysis strategy was employed to ...Pyrolysis technology has emerged as a promising method for converting waste polyurethane(WPU)from waste refrigerators into high-value chemicals.In this study,the copper(Cu)-assisted pyrolysis strategy was employed to enhance the thermal degradation efficiency and product quality of WPU.Kinetic analysis revealed that the activation energy(E_(a)) of the Cu-assisted pyrolysis was 136.64 kJ·mol^(−1) and Cu-assisted pyrolysis was controlled by the combined processes of diffusion,nucleation and phase boundary reactions.Comprehensive product analysis,including gas chromatography–mass spectrometry and thermogravimetric Fourier transform infrared spectroscopy–mass spectrometry suggested that Cu promoted the cleavage of urethane bonds and accelerated the decarboxylation of isocyanates,increasing the yields of aniline and ethanol at lower temperatures.Meanwhile,Cu effectively suppressed the formation of halogenated and heterocyclic compounds by promoting the cleavage of C–X(X=Cl,F)bonds through electron transfer interactions.Thus,the E_(a) is decreased and the halogenated compounds is reduced.This work provides the theoretical basis for converting waste to high-valued products through co-pyrolysis techniques.展开更多
Airless tires are essential for enhancing the safety,reliability,and convenience of maintenance of electric bicycles.Polyurethane(PU)is considered a promising candidate for such applications owing to its versatile pro...Airless tires are essential for enhancing the safety,reliability,and convenience of maintenance of electric bicycles.Polyurethane(PU)is considered a promising candidate for such applications owing to its versatile properties.However,their use is limited by insufficient heat resistance and excessive dynamic heat generation under cyclic loading.In this study,star-shaped trifunctional polypropylene glycerol(PPG3)was incorporated into conventional poly(tetramethylene glycol)(PTMG)and 4,4'-methylenediphenyl diisocyanate(MDI)-based systems to construct microporous star-shaped casting polyurethanes(SCPU),with water serving as a green foaming agent.Unlike conventional small-molecule trifunctional crosslinkers that create junctions within hard segment domains,PPG3 introduces long flexible arms between the hard segments,anchoring the crosslinking points at its molecular core.The large steric hindrance of PPG3 effectively suppresses soft segment crystallization and lowers the degree of microphase separation,whereas the crosslinked network restricts chain mobility,thereby reducing dynamic heat generation.These structural features also enhance the heat resistance,yielding a softening temperature of 183℃,which is 30.9%higher than that of polyurethane without PPG3.When applied to airless tires by casting SCPU into rubber treads,the fabricated hybrid airless tires achieved a rolling distance of over 3000 km under a load of 65 kg at 25km/h without structural failure,satisfying practical performance requirements.This strategy offers a simple,solvent-free,and environmentally friendly process,underscoring the potential of SCPU for scalable production of high-performance airless tires.展开更多
As a significant branch of smart materials,self-healing polyurethane materials mimic the biological damage repair mechanisms and have been widely applied in flexible electronics,functional coatings,biomedicine,and oth...As a significant branch of smart materials,self-healing polyurethane materials mimic the biological damage repair mechanisms and have been widely applied in flexible electronics,functional coatings,biomedicine,and other fields.This review systematically summarizes the design principles and recent advancements in both extrinsic and intrinsic self-healing polyurethane materials,highlighting their respective self-healing mechanisms and characteristics.For extrinsic system,damage repair is primarily achieved through microcapsules,hollow fibers,nanoparticles,and microvascular networks.However,their healing efficiency remains limited by the stability of carriers and the release kinetics of healing agents.In contrast,intrinsic self-healing polyurethane materials achieve self-healing through the reversibility of dynamic covalent and non-covalent bonds,which confer excellent self-healing capabilities while necessitating a precise balance between mechanical performance and self-healing efficiency.Moreover,their healing behavior is highly dependent on environmental conditions,potentially restricting their practical applications.Recent studies have demonstrated that the synergistic design of dynamic bonding networks can significantly enhance the mechanical properties,self-healing efficiency,and environmental adaptability.These developments offer new insights and theoretical foundations for designing high-performance self-healing polyurethane materials and may broaden their industrial applications.展开更多
Shotcrete is one of the common solutions for shallow sliding.It works by forming a protective layer with high strength and cementing the loose soil particles on the slope surface to prevent shallow sliding.However,the...Shotcrete is one of the common solutions for shallow sliding.It works by forming a protective layer with high strength and cementing the loose soil particles on the slope surface to prevent shallow sliding.However,the solidification time of conventional cement paste is long when shotcrete is used to treat cohesionless soil landslide.The idea of reinforcing slope with polyurethane solidified soil(i.e.,mixture of polyurethane and sand)was proposed.Model tests and finite element analysis were carried out to study the effectiveness of the proposed new method on the emergency treatment of cohesionless soil landslide.Surcharge loading on the crest of the slope was applied step by step until landslide was triggered so as to test and compare the stability and bearing capacity of slope models with different conditions.The simulated slope displacements were relatively close to the measured results,and the simulated slope deformation characteristics were in good agreement with the observed phenomena,which verifies the accuracy of the numerical method.Under the condition of surcharge loading on the crest of the slope,the unreinforced slope slid when the surcharge loading exceeded 30 k Pa,which presented a failure mode of local instability and collapse at the shallow layer of slope top.The reinforced slope remained stable even when the surcharge loading reached 48 k Pa.The displacement of the reinforced slope was reduced by more than 95%.Overall,this study verifies the effectiveness of polyurethane in the emergency treatment of cohesionless soil landslide and should have broad application prospects in the field of geological disasters concerning the safety of people's live.展开更多
Polyurethane foam,when used as a compressible layer in deep soft rock tunnels,offers a feasible solution to reduce the support pressure on the secondary lining.The foam spraying method using sprayed polyurethane mater...Polyurethane foam,when used as a compressible layer in deep soft rock tunnels,offers a feasible solution to reduce the support pressure on the secondary lining.The foam spraying method using sprayed polyurethane material is convenient for engineering applications;however,the compressive behaviour and feasibility of sprayed polyurethane material as a compressible layer remain unclear.To address this gap,this study conducts uniaxial compression tests and scanning electron microscope(SEM)tests to investigate the compressive behaviour of the rigid foams fabricated from a self-developed polyurethane spray material.A peridynamics model for the composite lining with a polyurethane compressible layer is then established.After validating the proposed method by comparison with two tests,a parametric study is carried out to investigate the damage evolution of the composite lining with a polyurethane compressible layer under various combinations of large deformations and compressible layer parameters.The results indicate that the polyurethane compressible layer effectively reduces the radial deformation and damage index of the secondary lining while increasing the damage susceptibility of the primary lining.The thickness of the polyurethane compressible layer significantly influences the prevention effect of large deformation-induced damage to the secondary lining within the density range of 50e100 kg/m^(3).In accordance with the experimental and simulation results,a simple,yet reasonable and convenient approach for determining the key parameters of the polyurethane compressible layer is proposed,along with a classification scheme for the parameters of the polyurethane compressible layer.展开更多
This study identified castor oil and phosphate ester as effective retarders through setting time,tensile,and flexural tests,and determined their optimal dosages.The mechanism by which phosphate ester affects the setti...This study identified castor oil and phosphate ester as effective retarders through setting time,tensile,and flexural tests,and determined their optimal dosages.The mechanism by which phosphate ester affects the setting time of polyurethane was further investigated using molecular dynamics simulations.Fourier transform infrared spectroscopy was also employed to systematically study the physical and chemical interactions between phosphate esters and polyurethane materials.The results demonstrate that a 1%concentration of phosphate ester provides the most effective retarding effect with minimal impact on the strength of polyurethane.When phosphate ester is added to the B component of the two-component polyurethane system,its interaction energy with component A decreases,as do the diffusion coefficient and aggregation degree of component B on the surface of component A.This reduction in interaction slows the setting time.Additionally,the addition of phosphate ester to polyurethane leads to the disappearance or weakening of functional groups,indicating competitive interactions within the phosphate ester components that inhibit the reaction rate.展开更多
Doping perylene diimide(PDI)into a polymer matrix is a simple strategy to prepare near-infrared(NIR)reflective materials,but the mechanical properties and NIR reflectance properties are significantly compromised due t...Doping perylene diimide(PDI)into a polymer matrix is a simple strategy to prepare near-infrared(NIR)reflective materials,but the mechanical properties and NIR reflectance properties are significantly compromised due to macro-phase separation.In this study,a novel polymer(denoted as PU-PDI)with intrinsic NIR reflective proper⁃ties was synthesized by covalent incorporation of PDI units into polyurethane chains.Its photophysical characteris⁃tics,mechanical property and NIR reflectance property are investigated in detail.The results show that covalent in⁃corporation reduces the severe aggregation of PDI units,thereby endows PU-PDI with excellent mechanical property.The elongation at break of PU-PDI can reach more than 700%,and the breaking strength is 34.11 MPa.Moreover,compared to the blending system,PU-PDI possesses enhanced NIR reflection ability due to the better dispersion of PDI units.展开更多
In this study,the polyurethanes(PU)were synthesized from 4,4′-methylene diphenyl diisocyanate and biobased ethoxylated castor oil or one to one mixture of ethoxylated and neat castor oil by direct mixing method.Utili...In this study,the polyurethanes(PU)were synthesized from 4,4′-methylene diphenyl diisocyanate and biobased ethoxylated castor oil or one to one mixture of ethoxylated and neat castor oil by direct mixing method.Utilization of ethoxylated castor oil increases tensile strength of PU up to 2.75 times(from3.2 to 8.8MPa),compared to PU based on neat castor oil.The PU composites filed with birch flour,diatomite and their mixture were prepared using home-made dissolver with cutter-shaped attachment at the speed of 1500 min−1.The tensile strength of PU composites filled with birch flour increases up to two time at loading 5–30 wt.%.Application of combined birch flour/diatomite additives has similar effect.The tensile strength of PU composites based on one to one mixture of ethoxylated and neat castor oil and filled with birch flour or combined birch flour/diatomite additives increases sharply up to 16–17 fold(up to 18.1 MPa).The birch flour and diatomite wellsoaked polymer matrix.The main factor determining mechanical performance is the morphology of PU samples and composites.Formation of ordered lamella-like structure of amorphous phase of PU matrix leads to an increase in mechanical performance and glass transition temperatures.Formation of disordered unstructured soft phase of starting PU leads to a decline of these functional properties.展开更多
In this study,dynamic selenonium salts were incorporated into a polyurethane(PU)matrix to develop transparent,healable and antibacterial coatings.Through systematic formulation optimization,optically clear materials w...In this study,dynamic selenonium salts were incorporated into a polyurethane(PU)matrix to develop transparent,healable and antibacterial coatings.Through systematic formulation optimization,optically clear materials with excellent room-temperature hardness were obtained.Fine-tuning the selenonium content established a synergy between antibacterial performance and network dynamics,as evidenced by vitrimer-like rheological behavior at elevated temperatures.Consequently,the coatings exhibited outstanding reprocessability while maintaining high transparency and structural stability after prolonged saltwater exposure.These integrated features underscore the potential of the developed cationic PU coatings as robust,multifunctional materials for electronic device protection and marine antifouling,combining long-term transparency,recyclability,and antibacterial durability.展开更多
Bio-polyol is considered as a core material to synthesize eco-friendly polyurethane products.However,one of the popular bio-polyols,polytrimethylene ether glycol(PO3G),is reluctant to crystallize and therefore exhibit...Bio-polyol is considered as a core material to synthesize eco-friendly polyurethane products.However,one of the popular bio-polyols,polytrimethylene ether glycol(PO3G),is reluctant to crystallize and therefore exhibits a cold crystallization behavior.This abnormal behavior causes unstable mechanical properties at low-temperature and limits its applications in shape memory devices where crystallization is an essential mechanism.To analyze the unusual phenomenon,we compared different ether polyols focusing on symmetry characteristics and the evenodd effect of carbon backbones.It is found that PO3G has a slow crystallization rate because its ether linkages require specific chain arrangement for attractive interactions.Consequently,a thermal learning mechanism is developed to restore the normal crystallization behavior of elastomers synthesized from the bio-polyol.Repetitive heating and cooling cycles with high-temperature annealing induce urethane exchange reaction and reconstruct the chain orientations for fast crystallization.Results suggest the degree of crystallizations in polyurethane elastomer can be precisely controlled by introducing repetitive thermal treatments to enhance the potential applications of bio-polyols in polymer industries.展开更多
Due to the limited regeneration capacity of myocardial tissue after infarction,designing tissue engineering scaffolds are in demand.In the present study,electrospun nanofibrous scaffolds were made out of polyurethane,...Due to the limited regeneration capacity of myocardial tissue after infarction,designing tissue engineering scaffolds are in demand.In the present study,electrospun nanofibrous scaffolds were made out of polyurethane,collagen and gold nanoparticles with random and aligned nanofiber morphologies.The nanoparticles were green-synthesized using saffron extract.Nanoparticle characterizations with UV-Vis.spectroscopy and DLS illustrated theoretical and hydrodynamic diameters of around 7 and 13 nm,respectively,having zeta potential of−37 mV.SEM and TEM micrographs showed the morphology and diameters of obtained nanofibers.Also,further characterization were done by ATR-FTIR,XRD and TGA investigations and degradation studies.Contact angle measurements showed hydrophilic nature of the scaffolds(59±0.6°for aligned PU/Col/Au50 nanofibers compared to 120±2.6°for random PU nanofibers).Mechanical testing demonstrated appropriate tensile properties of the scaffolds for cardiac tissue engineering(Young’s modulus:1.53±0.07 MPa for aligned PU/Col/Au50 nanofibers compared to 0.4±0.05 MPa for random PU nanofibers).Finally,alamar blue assay revealed proper survival of the cells of HUVEC cell line on the prepared scaffolds,where the highest percentages were observed for random and aligned PU/Col/Au50 nanofibers.According to the findings,the fabricated PU/Col/AuNPs nanofibrous scaffolds could be considered as potential cardiac patches.展开更多
Incorporation of acetal groups in the backbone is a potent strategy to create polymers that are cleavable or degradable under acidic conditions.We report here an in-depth study on the ring-closing-opening copolymeriza...Incorporation of acetal groups in the backbone is a potent strategy to create polymers that are cleavable or degradable under acidic conditions.We report here an in-depth study on the ring-closing-opening copolymerization of o-phthalaldehyde(OPA)and epoxide using Lewis pair type two-component organocatalysts for producing acetal-functionalized polyether and polyurethane.Notably,triethylborane as the Lewis acid,in comparison with tri(n-butyl)borane,more effectively enhances the polymerization activity by mitigating borane-induced reduction of the aldehyde group into extra initiating(borinic ester)species.Density functional theory(DFT)calculations present comparable energy barriers of OPA-epoxide cross-propagation and epoxide self-propagation,which is consistent with the experimental finding that an alternating-rich copolymer comprising mostly OPA-epoxide units but also epoxide-epoxide linkages is produced.In particular,when epoxide is added in a large excess,the product becomes a polyether containing acetal functionalities in the central part of the backbone and thus being convertible into polyurethane with refined acid degradability.展开更多
The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,h...The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,heightened lateral convergence,and internal force redistribution-may significantly compromise subway operational safety.Grouting remediation has become a widely adopted solution for tunnel deformation control and structural reinforcement.Developing optimized grouting materials is crucial for improving remediation effectiveness,ensuring structural integrity,and maintaining uninterrupted subway operations.This investigation explores the substitution of fine mortar aggregates with 0.1 mm discarded rubber particles at varying concentrations(0%,3%,6%,9%,12%,and 15%).Experimental parameters included three water-cement ratios(0.65,0.70,and 0.75)with constant 4%WPU content.Mechanical properties including compressive strength,flexural strength,and compression-to-bending ratio were evaluated across specified curing periods.Material characterization employed Fourier Transform Infrared Spectroscopy(FTIR)spectroscopy for molecular analysis and Scanning Electron Microscopy(SEM)for microstructural examination.Results indicate optimal toughness at 0.70 water-cement ratio with 6%rubber content,meeting mechanical pumping specifications while maintaining structural performance.展开更多
Boron adsorbents with high adsorption capacities have long been a focus of research for a long time.This study used small molecular polyols with different hydroxyl groups as functional monomers and as end-capping agen...Boron adsorbents with high adsorption capacities have long been a focus of research for a long time.This study used small molecular polyols with different hydroxyl groups as functional monomers and as end-capping agents,functional dendritic polyurethanes with nano structure were successfully prepared by one-pot method.The single molecule size and surface morphology were characterized by dynamic light scattering,transmission electron microscopy and scanning electron microscopy,and the molecular size in the dry state was 11 to 18 nm.The prepared materials were used as the boron adsorbents,and the effects of pH,time,boron solution concentration and temperature on the adsorption were studied.The results showed that the capacity of adsorbed boron could reach 110-130 mg·g^(-1).Adsorption was a homogeneous monolayer adsorption controlled by chemisorption,and adsorption thermodynamics showed that was a spontaneous endothermic process.Adsorption behavior was best described by the pseudo-second-order kinetic model and the Langmuir isotherm.This study also showed that it was difficult for ortho/meta-hydroxyl groups to chelate with H_(3)BO_(3) and other polyborates,and the chelates mainly had good chelating properties with B(OH)_(4)^(-),and the chelates formed had large steric hindrance.At the same time,increasing the number of hydroxyl groups of functional monomers was beneficial to increase the adsorption capacity of materials.In addition,the cyclic adsorption/desorption experiments showed that DPUs have good cyclic stability.At the same time,the adsorption results of the original salt lake brine showed that other metal ions in the brine had little effect on the adsorption of boron,and the adsorption capacity was as high as52.93 mg·g^(-1),and the maximum adsorption capacity was obtained by Adams-Bohart model to58.80 mg·g^(-1).The outstanding selectivity and adsorption capacity of these materials have broad potential application,and are expected to be used for the efficient adsorption and removal in boroncontaining water bodies.展开更多
基金financially supported by the National Natural Science Foundation of China(No.52503154)Shandong Provincial Natural Science Foundation(Nos.ZR2022MB034 and ZR2025QC512)。
文摘Azobenzene-based polymer actuators show great promise for photoactuation owing to their unique photoisomerization behavior and tailorable molecular programmability.However,conventional systems are limited by inadequate mechanical robustness,self-healing,and recyclability,hindering their practical implementation.Herein,we present a high-performance azobenzene-functionalized polyurethane(AzoPU)elastomer actuator designed via molecular engineering of photoactive azobenzene moieties and dynamic disulfide bonds.AzoPU exhibits exceptional mechanical properties with retained performance after multiple reshaping cycles,enabled by well-engineered hard-soft segments and synergistic stress dissipation from weak covalent bonds/hierarchical hydrogen bonds.It achieves over 93%self-healing efficiency at room temperature owing to the synergistic interplay of disulfide bonds in the polymer backbone and intermolecular hydrogen bonds.Furthermore,it demonstrates remarkable light-triggered actuation behavior,achieving a phototropic bending angle exceeding 180°toward the light source within 45 s.To showcase its practical potential,proof-of-concept photoactuated devices with flower-,hook-,and gripper-like and local-orientation processed strip-shaped structures were fabricated,which exhibited rapid and reversible light-triggered deformation.This study proposes a novel strategy for the development of intelligent polymeric materials that integrate light responsiveness,self-healing,and recyclability,thus holding great promise for applications in flexible electronics,smart actuators,and sustainable functional materials.
基金supported by the National Natural Science Foundation of China(52222302)。
文摘Reuse/recycling of expensive components in next-generation optoelectronic systems(e.g.,flexible electronics and foldable displays)for sustainability purposes impose stringent requirements on optically clear adhesive(OCA)with on-demand adhesion/deadhesion capability.Although some hot-melt OCAs have been developed,there still remain great challenges in balancing the mechanical property,adhesion/detachment and recyclability/reusability of the OCAs.Herein,we developed a debondable and robust polyurethane(PU)-based optically clear adhesive with both mechanical and chemical recyclability,overcoming the critical bottlenecks in sustainable advanced manufacturing.The ductile yet strong PU-based OCAs not only can adhere to various optically transparent glass and polymeric substrates(with a bonding strength high up to 5.0 MPa),but also exhibit deadhesion capability at high temperature owing to the thermally sensitive H-bonding interaction within the polymer network.The ondemand adhesion/deadhesion facilitates non-destructive detachment of functional assemblies and materials recycling/repair.The mechanical and chemical recyclability of PU-based OCAs can also effectively reduce the cost and address the endof-life issues.Moreover,the PU-based OCAs outperformed some commercial optical adhesives.In view of the straightforward synthesis,easy industrial scale-up and exceptional comprehensive properties,the PU-based OCAs will provide promising transformative solutions for advancing the circular economy and sustainability in next-generation optoelectronic devices.
基金supported by the Special Project for High-tech Industrialization of Science and Technology Cooperation between Jilin Province and Chinese Academy of Sciences(2023SYHZ0042)。
文摘The development of substitutable meniscus implants that can effectively protect articular cartilage remains a great challenge.Herein,a polyurethane with chemical crosslinking and sulfobetaine extenders containing hydrophobic chains(PU-CL-hSB)is developed,which could improve comprehensive properties and long-term stability simultaneously.By regulating the mole ratio of functional groups,PU-CL-hSB with appropriate mechanical properties,excellent tribological properties,and good fatigue resistance is used to prepare substitutable meniscus implant by hot-pressing.Due to the synergistic effect of functional groups,PU-CL-hSB meniscus implant presents comparable or even superior properties to native meniscus.It withstands a maximum force of 26.08 N versus 25.14 N for native meniscus,an energy dissipation from 45.93 to 39.17 N mm compared to 28.83 to 19.11 N mm for native meniscus over 300 cycles,and a friction coefficient from 0.08 to 0.19 compared to 0.11 to 0.26 for native meniscus.This PU-CL-hSB meniscus implant is further implanted into live rabbit knee joints for 8 and 25 weeks by a new approach,and in vivo data indicate that PU-CL-hSB meniscus implant not only protects articular cartilage from severe damage without eliciting inflammatory responses,but also can maintain normal physiological activities in the native state.Our findings present a substitutable meniscus implant that could be applied in vivo and propose evaluation methodologies for meniscus implants.
基金supported by the Russian state-funded project for ICBFM SB RAS(grant number 125012300656-5)。
文摘Background:The development of materials for cardiovascular surgery that would improve the effectiveness of surgical interventions remains an important task.Surgical intervention during the implantation of vascular prostheses and stents,and the body’s reaction to artificial materials,could lead to chronic inflammation,a local increase in the concentration of proinflammatory factors,and stimulation of unwanted tissue growth.The introduction of nonsteroidal anti-inflammatory drugs into implantable devices could be used to obtain vascular implants that do not induce inflammation and do not induce neointimal tissue outgrowth.Methods:The scaffolds were made by electrospinning from mixtures of polyurethane(PU)with diclofenac(DF).The kinetics of DF release from the scaffolds composed of 3%PU/10%HSA/3%DMSO/DF and 3%PU/DF were studied.The biocompatibility and anti-inflammatory effects of the obtained scaffolds on human gingival fibroblasts and umbilical vein endothelial cells were studied.Results:Both types of scaffolds are characterized by fast DF release.The viability of cells cultured on scaffolds is 2 times worse than that of cells cultured on plastic.The level of the proinflammatory cytokine IL-6 in the culture medium of cells cultured on DF-containing scaffolds was lower than that of cells cultured on scaffolds without DF.Conclusion:The introduction of DF into scaffolds minimizes the inflammation caused by cell reactions to an artificial material.
基金financially supported by the Hubei Key Laboratory of Pollutant Analysis&Reuse Technology(No.PA230102)。
文摘Polyurethane elastomers exhibit high dielectric constants owing to their polar groups,and can be used as energy storage capacitors.Energy storage depends not only on the dielectric constant but also on the dielectric loss.However,the relationship between chain structure and dielectric properties is not yet clear.Ketal-containing crosslinked polyurethane elastomers were prepared using cyclic ketal diol as a chain extender.The effect of the soft segment length on the dielectric properties and energy storage was investigated.The cause of the change in the dipolar polarization with the soft segment length was analyzed.As the soft segment length increased,the hard-soft hydrogen bonding decreased,whereas the hard-hard hydrogen bonding increased.Under the action of an electric field,the polar bonds in the ketal-containing polyurethane elastomer overcome the hydrogen bonding between hard-soft segments to produce polarization;meanwhile,they also experience crankshaft motions to generate polarization.The former has a relatively high relaxation activation energy of approximately 10-20 k J·mol^(-1),resulting in a large dielectric loss.The latter has a relatively low relaxation activation energy,approximately 0.7-1.7 kJ·mol^(-1),leading to low dielectric loss.As a result,the dielectric constant showed a decreasing trend,and the dielectric loss gradually decreased.This study provides a theoretical foundation for improving the dielectric properties of polyurethane elastomers.
文摘The development of intrinsically conductive piezoresistive sensors with high strain tolerance has garnered significant interest.While elastomeric polymers exhibit excellent strain capabilities,their utility in sensing applications has been limited by inherent challenges such as high electrical resistivity,poor aging resistance,and interfacial incompatibility.To address these limitations,hydroxyl-terminated polybutadiene(HTPB)-based polyurethane was chemically modified with acetylferrocene-polyaniline conductive moieties to enhance charge transport properties.Remarkably,this covalent functionalization endowed the resulting ferrocene-polyaniline hybrid polyurethane(FPHP)with a conductivity of2.33 n A at 1 V bias while preserving piezoresistive functionality.The FPHP demonstrated exceptional mechanical-electrical performance,achieving 254% elongation at break with strain-dependent gauge factors of 7.28(0%-12.5% strain,R^(2)=0.9504)and 19.66(12.5%-35.0% strain,R^(2)=0.9929).Further characterization revealed a rapid 0.60 s response time and stability over 3500 strain-release cycles at compression strain,underscoring its durability under repetitive loading.The FPHP sensor was capable of monitoring various human movements and recognizing writing signals.These advances establish a materials design paradigm for fabricating flexible sensors that synergistically integrate high deformability,tunable sensitivity,and robust operational stability,positioning FPHP as a promising candidate for next-generation wearable electronics and soft robotics.
基金supported by the Natural Science Foundation of Shandong Province(ZR2022QE042)China Postdoctoral Science Foundation(2023M741856)the National Natural Science Foundation of China(52172093).
文摘Pyrolysis technology has emerged as a promising method for converting waste polyurethane(WPU)from waste refrigerators into high-value chemicals.In this study,the copper(Cu)-assisted pyrolysis strategy was employed to enhance the thermal degradation efficiency and product quality of WPU.Kinetic analysis revealed that the activation energy(E_(a)) of the Cu-assisted pyrolysis was 136.64 kJ·mol^(−1) and Cu-assisted pyrolysis was controlled by the combined processes of diffusion,nucleation and phase boundary reactions.Comprehensive product analysis,including gas chromatography–mass spectrometry and thermogravimetric Fourier transform infrared spectroscopy–mass spectrometry suggested that Cu promoted the cleavage of urethane bonds and accelerated the decarboxylation of isocyanates,increasing the yields of aniline and ethanol at lower temperatures.Meanwhile,Cu effectively suppressed the formation of halogenated and heterocyclic compounds by promoting the cleavage of C–X(X=Cl,F)bonds through electron transfer interactions.Thus,the E_(a) is decreased and the halogenated compounds is reduced.This work provides the theoretical basis for converting waste to high-valued products through co-pyrolysis techniques.
基金financially supported by the National Natural Science Foundation of China(No.52303063)Hubei Provincial Department of Education Guided Scientific Research Project(No.B2024056)。
文摘Airless tires are essential for enhancing the safety,reliability,and convenience of maintenance of electric bicycles.Polyurethane(PU)is considered a promising candidate for such applications owing to its versatile properties.However,their use is limited by insufficient heat resistance and excessive dynamic heat generation under cyclic loading.In this study,star-shaped trifunctional polypropylene glycerol(PPG3)was incorporated into conventional poly(tetramethylene glycol)(PTMG)and 4,4'-methylenediphenyl diisocyanate(MDI)-based systems to construct microporous star-shaped casting polyurethanes(SCPU),with water serving as a green foaming agent.Unlike conventional small-molecule trifunctional crosslinkers that create junctions within hard segment domains,PPG3 introduces long flexible arms between the hard segments,anchoring the crosslinking points at its molecular core.The large steric hindrance of PPG3 effectively suppresses soft segment crystallization and lowers the degree of microphase separation,whereas the crosslinked network restricts chain mobility,thereby reducing dynamic heat generation.These structural features also enhance the heat resistance,yielding a softening temperature of 183℃,which is 30.9%higher than that of polyurethane without PPG3.When applied to airless tires by casting SCPU into rubber treads,the fabricated hybrid airless tires achieved a rolling distance of over 3000 km under a load of 65 kg at 25km/h without structural failure,satisfying practical performance requirements.This strategy offers a simple,solvent-free,and environmentally friendly process,underscoring the potential of SCPU for scalable production of high-performance airless tires.
基金sponsored by the National Key Research and Devel-opment Program of China(2023YFD1800105)Guangdong Province Science&Technology Program(2024B1515040004)Guangzhou Sci-ence and Technology Plan Project(2024A04J6354).
文摘As a significant branch of smart materials,self-healing polyurethane materials mimic the biological damage repair mechanisms and have been widely applied in flexible electronics,functional coatings,biomedicine,and other fields.This review systematically summarizes the design principles and recent advancements in both extrinsic and intrinsic self-healing polyurethane materials,highlighting their respective self-healing mechanisms and characteristics.For extrinsic system,damage repair is primarily achieved through microcapsules,hollow fibers,nanoparticles,and microvascular networks.However,their healing efficiency remains limited by the stability of carriers and the release kinetics of healing agents.In contrast,intrinsic self-healing polyurethane materials achieve self-healing through the reversibility of dynamic covalent and non-covalent bonds,which confer excellent self-healing capabilities while necessitating a precise balance between mechanical performance and self-healing efficiency.Moreover,their healing behavior is highly dependent on environmental conditions,potentially restricting their practical applications.Recent studies have demonstrated that the synergistic design of dynamic bonding networks can significantly enhance the mechanical properties,self-healing efficiency,and environmental adaptability.These developments offer new insights and theoretical foundations for designing high-performance self-healing polyurethane materials and may broaden their industrial applications.
基金the financial support from the Fujian Science Foundation for Outstanding Youth(2023J06039)the National Natural Science Foundation of China(Grant No.41977259,U2005205,41972268)the Independent Research Project of Technology Innovation Center for Monitoring and Restoration Engineering of Ecological Fragile Zone in Southeast China(KY-090000-04-2022-019)。
文摘Shotcrete is one of the common solutions for shallow sliding.It works by forming a protective layer with high strength and cementing the loose soil particles on the slope surface to prevent shallow sliding.However,the solidification time of conventional cement paste is long when shotcrete is used to treat cohesionless soil landslide.The idea of reinforcing slope with polyurethane solidified soil(i.e.,mixture of polyurethane and sand)was proposed.Model tests and finite element analysis were carried out to study the effectiveness of the proposed new method on the emergency treatment of cohesionless soil landslide.Surcharge loading on the crest of the slope was applied step by step until landslide was triggered so as to test and compare the stability and bearing capacity of slope models with different conditions.The simulated slope displacements were relatively close to the measured results,and the simulated slope deformation characteristics were in good agreement with the observed phenomena,which verifies the accuracy of the numerical method.Under the condition of surcharge loading on the crest of the slope,the unreinforced slope slid when the surcharge loading exceeded 30 k Pa,which presented a failure mode of local instability and collapse at the shallow layer of slope top.The reinforced slope remained stable even when the surcharge loading reached 48 k Pa.The displacement of the reinforced slope was reduced by more than 95%.Overall,this study verifies the effectiveness of polyurethane in the emergency treatment of cohesionless soil landslide and should have broad application prospects in the field of geological disasters concerning the safety of people's live.
基金financially supported by the National Key Research and Development Program of China(Grant Nos.2023YFB2604005)the National Key Research and Development 451 Program of China(Grant No.2021YFC3100803)the Yangtze River Water Science Research Joint Fund Key Project of National Natural Science Foundation of China(Grant No.U2340231).
文摘Polyurethane foam,when used as a compressible layer in deep soft rock tunnels,offers a feasible solution to reduce the support pressure on the secondary lining.The foam spraying method using sprayed polyurethane material is convenient for engineering applications;however,the compressive behaviour and feasibility of sprayed polyurethane material as a compressible layer remain unclear.To address this gap,this study conducts uniaxial compression tests and scanning electron microscope(SEM)tests to investigate the compressive behaviour of the rigid foams fabricated from a self-developed polyurethane spray material.A peridynamics model for the composite lining with a polyurethane compressible layer is then established.After validating the proposed method by comparison with two tests,a parametric study is carried out to investigate the damage evolution of the composite lining with a polyurethane compressible layer under various combinations of large deformations and compressible layer parameters.The results indicate that the polyurethane compressible layer effectively reduces the radial deformation and damage index of the secondary lining while increasing the damage susceptibility of the primary lining.The thickness of the polyurethane compressible layer significantly influences the prevention effect of large deformation-induced damage to the secondary lining within the density range of 50e100 kg/m^(3).In accordance with the experimental and simulation results,a simple,yet reasonable and convenient approach for determining the key parameters of the polyurethane compressible layer is proposed,along with a classification scheme for the parameters of the polyurethane compressible layer.
基金Funded by the National Natural Science Foundation of China(No.52370128)the Fundamental Research Funds for the Central Universities(No.2572022AW54)。
文摘This study identified castor oil and phosphate ester as effective retarders through setting time,tensile,and flexural tests,and determined their optimal dosages.The mechanism by which phosphate ester affects the setting time of polyurethane was further investigated using molecular dynamics simulations.Fourier transform infrared spectroscopy was also employed to systematically study the physical and chemical interactions between phosphate esters and polyurethane materials.The results demonstrate that a 1%concentration of phosphate ester provides the most effective retarding effect with minimal impact on the strength of polyurethane.When phosphate ester is added to the B component of the two-component polyurethane system,its interaction energy with component A decreases,as do the diffusion coefficient and aggregation degree of component B on the surface of component A.This reduction in interaction slows the setting time.Additionally,the addition of phosphate ester to polyurethane leads to the disappearance or weakening of functional groups,indicating competitive interactions within the phosphate ester components that inhibit the reaction rate.
文摘Doping perylene diimide(PDI)into a polymer matrix is a simple strategy to prepare near-infrared(NIR)reflective materials,but the mechanical properties and NIR reflectance properties are significantly compromised due to macro-phase separation.In this study,a novel polymer(denoted as PU-PDI)with intrinsic NIR reflective proper⁃ties was synthesized by covalent incorporation of PDI units into polyurethane chains.Its photophysical characteris⁃tics,mechanical property and NIR reflectance property are investigated in detail.The results show that covalent in⁃corporation reduces the severe aggregation of PDI units,thereby endows PU-PDI with excellent mechanical property.The elongation at break of PU-PDI can reach more than 700%,and the breaking strength is 34.11 MPa.Moreover,compared to the blending system,PU-PDI possesses enhanced NIR reflection ability due to the better dispersion of PDI units.
文摘In this study,the polyurethanes(PU)were synthesized from 4,4′-methylene diphenyl diisocyanate and biobased ethoxylated castor oil or one to one mixture of ethoxylated and neat castor oil by direct mixing method.Utilization of ethoxylated castor oil increases tensile strength of PU up to 2.75 times(from3.2 to 8.8MPa),compared to PU based on neat castor oil.The PU composites filed with birch flour,diatomite and their mixture were prepared using home-made dissolver with cutter-shaped attachment at the speed of 1500 min−1.The tensile strength of PU composites filled with birch flour increases up to two time at loading 5–30 wt.%.Application of combined birch flour/diatomite additives has similar effect.The tensile strength of PU composites based on one to one mixture of ethoxylated and neat castor oil and filled with birch flour or combined birch flour/diatomite additives increases sharply up to 16–17 fold(up to 18.1 MPa).The birch flour and diatomite wellsoaked polymer matrix.The main factor determining mechanical performance is the morphology of PU samples and composites.Formation of ordered lamella-like structure of amorphous phase of PU matrix leads to an increase in mechanical performance and glass transition temperatures.Formation of disordered unstructured soft phase of starting PU leads to a decline of these functional properties.
基金financially supported by the National Natural Science Foundation of China(Nos.21971177 and 52503155)Natural Science Foundation of the Jiangsu Higher Education Institution of China(No.22KJA150004)+7 种基金China Scholarship Council(No.202206920034)Research Foundation Flanders(FWO)(Application 1S34725N)Priority Academic Program Development(PAPD)of Jiangsu Higher Education InstitutionsJiangsu Key Laboratory of Advanced Functional Polymers Design and ApplicationSoochow UniversitySuzhou Key Laboratory of Macromolecular Design and Precision SynthesisProgram of Innovative Research Team of Soochow Universityfunding from the European Research Council(ERC)under the European Union’s Horizon 2020 Research and Innovation Program 101021081(ERC-AdG-2020,CiMaC-project)。
文摘In this study,dynamic selenonium salts were incorporated into a polyurethane(PU)matrix to develop transparent,healable and antibacterial coatings.Through systematic formulation optimization,optically clear materials with excellent room-temperature hardness were obtained.Fine-tuning the selenonium content established a synergy between antibacterial performance and network dynamics,as evidenced by vitrimer-like rheological behavior at elevated temperatures.Consequently,the coatings exhibited outstanding reprocessability while maintaining high transparency and structural stability after prolonged saltwater exposure.These integrated features underscore the potential of the developed cationic PU coatings as robust,multifunctional materials for electronic device protection and marine antifouling,combining long-term transparency,recyclability,and antibacterial durability.
基金supported by the Basic Science Research Program through the National Research Foundation of Korea(NRF)funded by the Ministry of Science and ICT(RS-2024-00451587)supported by Post-plastic Specialized Graduate Program through the Korea Environmental Industry&Technology Institute(KEITI)funded by the Ministry of Environment(MOE).
文摘Bio-polyol is considered as a core material to synthesize eco-friendly polyurethane products.However,one of the popular bio-polyols,polytrimethylene ether glycol(PO3G),is reluctant to crystallize and therefore exhibits a cold crystallization behavior.This abnormal behavior causes unstable mechanical properties at low-temperature and limits its applications in shape memory devices where crystallization is an essential mechanism.To analyze the unusual phenomenon,we compared different ether polyols focusing on symmetry characteristics and the evenodd effect of carbon backbones.It is found that PO3G has a slow crystallization rate because its ether linkages require specific chain arrangement for attractive interactions.Consequently,a thermal learning mechanism is developed to restore the normal crystallization behavior of elastomers synthesized from the bio-polyol.Repetitive heating and cooling cycles with high-temperature annealing induce urethane exchange reaction and reconstruct the chain orientations for fast crystallization.Results suggest the degree of crystallizations in polyurethane elastomer can be precisely controlled by introducing repetitive thermal treatments to enhance the potential applications of bio-polyols in polymer industries.
基金supported by Shiraz University of Medical Sciences,Shiraz,Iran(grant No.:17780).
文摘Due to the limited regeneration capacity of myocardial tissue after infarction,designing tissue engineering scaffolds are in demand.In the present study,electrospun nanofibrous scaffolds were made out of polyurethane,collagen and gold nanoparticles with random and aligned nanofiber morphologies.The nanoparticles were green-synthesized using saffron extract.Nanoparticle characterizations with UV-Vis.spectroscopy and DLS illustrated theoretical and hydrodynamic diameters of around 7 and 13 nm,respectively,having zeta potential of−37 mV.SEM and TEM micrographs showed the morphology and diameters of obtained nanofibers.Also,further characterization were done by ATR-FTIR,XRD and TGA investigations and degradation studies.Contact angle measurements showed hydrophilic nature of the scaffolds(59±0.6°for aligned PU/Col/Au50 nanofibers compared to 120±2.6°for random PU nanofibers).Mechanical testing demonstrated appropriate tensile properties of the scaffolds for cardiac tissue engineering(Young’s modulus:1.53±0.07 MPa for aligned PU/Col/Au50 nanofibers compared to 0.4±0.05 MPa for random PU nanofibers).Finally,alamar blue assay revealed proper survival of the cells of HUVEC cell line on the prepared scaffolds,where the highest percentages were observed for random and aligned PU/Col/Au50 nanofibers.According to the findings,the fabricated PU/Col/AuNPs nanofibrous scaffolds could be considered as potential cardiac patches.
基金financially supported by the National Key R&D Program of China(No.2022YFC2805103)the National Natural Science Foundation of China(Nos.52022031 and 52263001)the Foundation from Qinghai Science and Technology Department(No.2022-ZJ-944Q)。
文摘Incorporation of acetal groups in the backbone is a potent strategy to create polymers that are cleavable or degradable under acidic conditions.We report here an in-depth study on the ring-closing-opening copolymerization of o-phthalaldehyde(OPA)and epoxide using Lewis pair type two-component organocatalysts for producing acetal-functionalized polyether and polyurethane.Notably,triethylborane as the Lewis acid,in comparison with tri(n-butyl)borane,more effectively enhances the polymerization activity by mitigating borane-induced reduction of the aldehyde group into extra initiating(borinic ester)species.Density functional theory(DFT)calculations present comparable energy barriers of OPA-epoxide cross-propagation and epoxide self-propagation,which is consistent with the experimental finding that an alternating-rich copolymer comprising mostly OPA-epoxide units but also epoxide-epoxide linkages is produced.In particular,when epoxide is added in a large excess,the product becomes a polyether containing acetal functionalities in the central part of the backbone and thus being convertible into polyurethane with refined acid degradability.
基金supported by the National Natural Science Foundation of China,Grant Nos.42477185,41602308the Zhejiang Provincial Natural Science Foundation of China,Grant No.LY20E080005+2 种基金the Zhejiang Province University Students Science and Technology Innovation Program,Grant No.0201310P28the PostGraduate Course Construction Project of Zhejiang University of Science and Technology,Grant No.2021yjskj05the Zhejiang University of Science and Technology Graduate Research and Innovation Fund,Grant No.2023yjskc10.
文摘The ongoing operation of subway systems makes existing tunnels vulnerable to deformations and structural damage caused by adjacent foundation pit construction.Such deformations-manifesting as horizontal displacement,heightened lateral convergence,and internal force redistribution-may significantly compromise subway operational safety.Grouting remediation has become a widely adopted solution for tunnel deformation control and structural reinforcement.Developing optimized grouting materials is crucial for improving remediation effectiveness,ensuring structural integrity,and maintaining uninterrupted subway operations.This investigation explores the substitution of fine mortar aggregates with 0.1 mm discarded rubber particles at varying concentrations(0%,3%,6%,9%,12%,and 15%).Experimental parameters included three water-cement ratios(0.65,0.70,and 0.75)with constant 4%WPU content.Mechanical properties including compressive strength,flexural strength,and compression-to-bending ratio were evaluated across specified curing periods.Material characterization employed Fourier Transform Infrared Spectroscopy(FTIR)spectroscopy for molecular analysis and Scanning Electron Microscopy(SEM)for microstructural examination.Results indicate optimal toughness at 0.70 water-cement ratio with 6%rubber content,meeting mechanical pumping specifications while maintaining structural performance.
基金financially supported by Applied Basic Research Project of Qinghai province(2023-ZJ-774)。
文摘Boron adsorbents with high adsorption capacities have long been a focus of research for a long time.This study used small molecular polyols with different hydroxyl groups as functional monomers and as end-capping agents,functional dendritic polyurethanes with nano structure were successfully prepared by one-pot method.The single molecule size and surface morphology were characterized by dynamic light scattering,transmission electron microscopy and scanning electron microscopy,and the molecular size in the dry state was 11 to 18 nm.The prepared materials were used as the boron adsorbents,and the effects of pH,time,boron solution concentration and temperature on the adsorption were studied.The results showed that the capacity of adsorbed boron could reach 110-130 mg·g^(-1).Adsorption was a homogeneous monolayer adsorption controlled by chemisorption,and adsorption thermodynamics showed that was a spontaneous endothermic process.Adsorption behavior was best described by the pseudo-second-order kinetic model and the Langmuir isotherm.This study also showed that it was difficult for ortho/meta-hydroxyl groups to chelate with H_(3)BO_(3) and other polyborates,and the chelates mainly had good chelating properties with B(OH)_(4)^(-),and the chelates formed had large steric hindrance.At the same time,increasing the number of hydroxyl groups of functional monomers was beneficial to increase the adsorption capacity of materials.In addition,the cyclic adsorption/desorption experiments showed that DPUs have good cyclic stability.At the same time,the adsorption results of the original salt lake brine showed that other metal ions in the brine had little effect on the adsorption of boron,and the adsorption capacity was as high as52.93 mg·g^(-1),and the maximum adsorption capacity was obtained by Adams-Bohart model to58.80 mg·g^(-1).The outstanding selectivity and adsorption capacity of these materials have broad potential application,and are expected to be used for the efficient adsorption and removal in boroncontaining water bodies.
