Near-infrared(NIR)light-responsive shape memory polymers(SMPs)show great promise for biomedical applications,but conventional photothermal agents suffer from high cost,complex preparation,or poor biocompatibility,whil...Near-infrared(NIR)light-responsive shape memory polymers(SMPs)show great promise for biomedical applications,but conventional photothermal agents suffer from high cost,complex preparation,or poor biocompatibility,while lignin-based alternatives exhibit insufficient photothermal conversion efficiency.Herein,we developed a novel strategy to enhance photothermal performance of lignin through sequential demethylation modification and Fe^(3+)complexation for constructing NIR light responsive SMPs.Dealkaline lignin(DL)was first demethylated using iodocyclohexane to produce demethylated lignin(DDL)with increased catechol content,which was then incorporated into polycaprolactone-based polyurethane synthesis followed by Fe^(3+)complexation.Results showed that DDL-Fe^(3+)complexes have significantly enhanced photothermal conversion performance,and the resulting PU-DDL+Fe^(3+)polyurethane with 0.5 wt%DDL content demonstrated a temperature increases of 39.8℃under 0.33 W·cm-2808 nm NIR irradiation.This excellent photothermal performance enables the shape-fixed PU-DDL+Fe^(3+)polyurethane to rapidly recover to its initial shape under NIR light irradiation.Additionally,PU-DDL+Fe^(3+)polyurethane exhibits good mechanical properties and biocompatibility,demonstrating significant biomedical application potential.展开更多
The synthesis of polyurethanes(PUs)from the reaction of low molecular weight poly(ethylene carbonate)diol(PECD)is rarely investigated.This work reports a novel PU with excellent mechanical properties from the solution...The synthesis of polyurethanes(PUs)from the reaction of low molecular weight poly(ethylene carbonate)diol(PECD)is rarely investigated.This work reports a novel PU with excellent mechanical properties from the solution polymerization of 4,4-diphenylmethane diisocyanate(MDI)with PECD that was derived from the copolymerization of carbon dioxide(CO_(2))and ethylene oxide(EO).The tensile strength,the elongation at break and 300%constant tensile strength of the PECD-PU were up to 66±2 MPa,880%±50%and 13 MPa,respectively,higher than the control PUs from the reaction of MDI with commercial polyethers or polyesters.The PECD-PU with high CO_(2) carbonate content exhibited good solvent resistance and chemical stability.Of importance,the mechanical properties and chemical resistance of PECD-PU were significantly enhanced with the increasing content of CO_(2),i.e.,the carbonate unit in PECD.This work provides comprehensive properties of PECD-derived PUs,indicating that PECD is a competitive precursor for the preparation of PU and has broad application prospects.展开更多
In this study,a facile method was employed to synthesize strong,yet highly elastic polyurethane-urea(PUU)with typical characteristics and 94% optical transmittance.Graphene platelets(GNPs)were prepared and modified vi...In this study,a facile method was employed to synthesize strong,yet highly elastic polyurethane-urea(PUU)with typical characteristics and 94% optical transmittance.Graphene platelets(GNPs)were prepared and modified via a scalable and eco-friendly mechanochemical approach.The produced GNPs is at 1.6-nm thickness with high electrical conductivity of~950 S/m.The structure-property relations of PUU/GNP nanocomposites were comprehensively investigated through morphology and mechanical properties measurements.The strong interface and high-density hydrogen bonds between modified GNPs(M-GNPs)and PUU significantly enhanced the mechanical properties of the PUU nanocomposite.The PUU composite showed 66.7%and 36.2%increments in tensile and impact strengths,respectively,at 0.2 wt% M-GNPs.The reversible hydrogen bond between M-GNPs and PUU endowed the nanocomposite with self-healing properties achieving 97.8% healing efficiency of the strength after 5 h at 120℃.This study demonstrates the importance of surface modification and provides a simple yet robust approach for preparing high-performance and functional PUU/graphene composites.展开更多
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
Recent advancements in developing tannin-based non-isocyanate polyurethane(NIPU)resins have unlocked new possibilities for sustainable and eco-friendly wood adhesives.Unlike conventional polyurethane,NIPUs eliminate h...Recent advancements in developing tannin-based non-isocyanate polyurethane(NIPU)resins have unlocked new possibilities for sustainable and eco-friendly wood adhesives.Unlike conventional polyurethane,NIPUs eliminate hazardous isocyanates,offering safer alternatives for industrial applications.Tannin,a naturally occurring polyphenolic compound,plays a pivotal role in enhancing these resins’fire-resistance and super-hydrophobic properties.This review highlights key developments in synthesizing tannin-based NIPU,focusing on various polymerization techniques such as polyaddition,polycondensation,ring-opening polymerization,and rearrangement.These strategies contribute to improved mechanical strength,thermal stability,and resistance to water absorption.Recent studies demonstrate that tannin-based NIPU adhesives meet or exceed international internal bonding strength,elasticity,and durability standards.Their application in wood-based composites like oriented strand boards(OSB)has shown promising results,offering improved resistance to moisture and superior dimensional stability.Furthermore,the cross-linked polymer network,supported by chemical modifications like the introduction of fluoroalkyl groups,significantly enhances hydrophobicity and fire retardancy.Despite these advancements,challenges remain in terms of scalability,cost,and integration with existing manufacturing processes.Future research should focus on optimizing reaction conditions,improving raw material availability,and developing industrial-scale production methods.This review underscores the potential of tannin-based NIPU resins as a viable and sustainable alternative for various wood composite applications.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
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
This study aimed to systematically regulate the performance of 4D printing composites by investigating the synergistic effects of dicumyl peroxide(DCP)and maleic anhydride-grafted polyethylene(MAH-g-PE)on a poly(lacti...This study aimed to systematically regulate the performance of 4D printing composites by investigating the synergistic effects of dicumyl peroxide(DCP)and maleic anhydride-grafted polyethylene(MAH-g-PE)on a poly(lactic acid)/thermoplastic polyurethane(PLA/TPU)matrix.Specifically,using a 70 wt%/30 wt%PLA/TPU matrix and an L_(9)(3^(2))orthogonal design,composites were evaluated via morphology,shape memory,mechanical tests,and multi-criteria analysis.Moderate DCP enhanced crosslinking,improving storage modulus and thermal stability,while excessive DCP caused brittleness.Furthermore,MAH-g-PE effectively improved interfacial compatibility,and its synergy with DCP was dosage-dependent.Consequently,Sample 5 achieved optimal performance,exhibiting uniform fracture morphology,a shape fixation rate of98.8%with the fastest recovery,and balanced strength-ductility.Multi-criteria analysis identified elongation at break and recovery time as the top contributing factors,with consistent rankings validated by Spearman analysis(ρ=0.833,p<0.01).In summary,adjusting DCP and MAH-g-PE contents effectively modulates the crosslinking structure and interfacial properties of PLA/TPU composites,providing a viable strategy for developing high-performance,tunable 4D printing materials.展开更多
Silane terminated prepolymers for adhesives, sealants and coatings are of <span style="font-family:"">great industrial importance. They are very important because of their low toxicity over polyur...Silane terminated prepolymers for adhesives, sealants and coatings are of <span style="font-family:"">great industrial importance. They are very important because of their low toxicity over polyurethanes, silicones, and solvent-based products. Hence, many pieces of literature which deal with the synthesis, properties and applications of this Silane terminated polymers hybrid system exist. Silylated polyether (MS polymers) and Silylated Polyurethane Polymers (SPUR) are the bases for numerous sealants, adhesives and coatings used worldwide. A hybrid system mixed with organic-polyurethane proportion and inorganic-alkoxysilane proportion combines the benefits of conventional polyurethane and silicone-based products. This article reviews the chemistry of MS polymers and SPUR and their advantages and disadvantages in silyl terminated prepolymer-based adhesives, sealants and coatings as well as provides information on different end applications.展开更多
Polyurethanes consisting of tri-functional homopolymer of hexamethylene diisocyanate （tri-HDI） and polyethylene glycol （PEG） are synthesized, in which photo-reversible coumarin moieties act as pendant groups. Acco...Polyurethanes consisting of tri-functional homopolymer of hexamethylene diisocyanate （tri-HDI） and polyethylene glycol （PEG） are synthesized, in which photo-reversible coumarin moieties act as pendant groups. Accordingly, the polyurethanes can be repeatedly self-healed under UV lights at room temperature by taking advantages of the photodimerization and photocleavage habits of coumarin. Molecular weight of the soft segment, PEG, is found to be closely related to the healing performance of the polyurethanes. Lower molecular weight PEG that corresponds to higher initial coumarin concentration in the polymer is critical for obtaining higher healing efficiency in the case of the first healing action. Nevertheless, it does not guarantee high reversibility of the photo-remendability during the repeated healing events. In contrast, the polyurethane with moderate molecular weight PEG has achieved balanced performance. Reaction kinetics is less important for the healing effect.展开更多
To better investigate the degradation and biocompatibility of waterborne biodegradable polyurethanes for tissue engineering, a series of new waterborne biodegradable polyurethanes （PEGPUs） with low degree of crossli...To better investigate the degradation and biocompatibility of waterborne biodegradable polyurethanes for tissue engineering, a series of new waterborne biodegradable polyurethanes （PEGPUs） with low degree of crosslinking was synthesized using IPDI, BDO and L-lysine as hard segments, PCL and PEG as soft segment. The bulk structures and properties of the prepared polyurethanes were characterized by Fourier transform infrared spectroscopy （FTIR）, differential scanning calorimetry （DSC）, tensile mechanical tests and water contact angle （WCA） measurements. The degree of microphase separation was slightly improved because of the lowered crosslinking degree of these PEGPUs in comparison with the high cross-linking degree samples, leading to good mechanical properties, as indicated by DSC and stress-strain data. Moreover, biodegradability of the polyurethanes was evaluated in phosphate buffer solutions （PBS） under different pH values and enzymatic solution at pH 7.4 through weight loss monitoring. The results suggested that the degradation of these PEGPUs was closely related to their bulk and surface properties. And the degradation products didn＇t show apparent inhibition effect against fibroblasts in vitro. These studies demonstrated that the waterborne biodegradable polyurethanes could find potential use in soft tissue engineering and tissue regeneration.展开更多
Polyurethanes（PU） were prepared using toluene diisocyanate,polypropylene glycol,ethylene glycol, dimethylolpropionic acid and triethylamine,and a siloxane modified PU（PSU） was obtained through reaction of the PU p...Polyurethanes（PU） were prepared using toluene diisocyanate,polypropylene glycol,ethylene glycol, dimethylolpropionic acid and triethylamine,and a siloxane modified PU（PSU） was obtained through reaction of the PU prepolymers with bis（3-（1-methoxy-2-hydroxypropoxy）propyl） terminated polysiloxanes（PMTS） of different molecular weight,specifically designed for this purpose.Results showed that,with increases in molecular weight of PMTS and its content,viscosity of the final PSU latexes decreased;phase separation of the incorporated PMTS in PSU films increased;the average particle sizes of the latexes varied between 110 nm and 330 nm,and the surface tension in the final latexes was relatively constant regardless of PMTS amount and its molecular weight.It was likely that copolymerized polysiloxanes had trend to enrich on top of the film when PMTS molecular weight was around 2000 and its content above 5 wt%.In general, PMTS modified polyurethane films showed higher performance than those from unmodified waterborne polyurethane latexes.展开更多
Waterborne polyurethane composites containing silica nanoparticles are synthesized successfully via the in situ polymerization. The structure, thermal stability, surface hardness, tensile strength, UV-Vis absorbance, ...Waterborne polyurethane composites containing silica nanoparticles are synthesized successfully via the in situ polymerization. The structure, thermal stability, surface hardness, tensile strength, UV-Vis absorbance, dynamic mechanical properties and chemicals resistance of the resulting composites are investigated by FTIR, TEM, TGA, UV-Vis, DMA and chemicals soakage measurements. Results show that polyurethane molecules and silica nanoparticles are linked with covalent bonds. As a result, physical properties of polyurethane composites, such as thermal stability, surface hardness, weather and chemicals resistance are all improved when an appropriate concentration of silica nanoparticles are incorporated.展开更多
Thermomechanical properties of polyurethanes（PUs） strongly depend on the molecular interactions and microphase structure. In this work, two chain extenders with different ratios, flexile 1,4-butanediol（BDO） and br...Thermomechanical properties of polyurethanes（PUs） strongly depend on the molecular interactions and microphase structure. In this work, two chain extenders with different ratios, flexile 1,4-butanediol（BDO） and branched trimethylolpropane mono allyl ether（TMPAE）, are used to tune the molecular interactions and microphase structures of a series of biodegradable thermoplastic polyurethanes（TPUs）. In TPUs, the biodegradable polycaprolactone（PCL, M_n of 2000） is used as soft segment while 1,6-diisocyanatohexane（HDI） and chain extenders are used as hard segment. Fourier transform infrared spectroscopy（FTIR）, proton nuclear magnetic resonance spectroscppy（~1 H-NMR）, gel permeation chromatography（GPC）, differential scanning calorimetry（DSC）, dynamic mechanical analysis（DMA） and mechanical tests were performed to characterize the bulk structure and properties of TPUs. Compared with BDO, the steric bulk of TMPAE is larger. The increment of TMPAE can help to increase the hydrogen bond content, microphase separation, and the elastic modulus ratio（R）, which would strongly affect the thermomechanical property of the TPUs. The results of this work verify the importance of the structure of chain extender on the properties of TPUs. It provides valuable information for further understanding the structure-property relationships of these polyurethanes.展开更多
A series of fluorinated phosphatidylcholine polyurethane macromolecular additives were synthesized by solution polymerization using methylenebis（phylene isocyanates） （MDI） and 1,4-butanediol （BDO） as hard segmen...A series of fluorinated phosphatidylcholine polyurethane macromolecular additives were synthesized by solution polymerization using methylenebis（phylene isocyanates） （MDI） and 1,4-butanediol （BDO） as hard segments, a new phoshporycholine, 2-（2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-10-（2-hydroxyethoxy）decyloxy） ethyl phosphorycholine （HDFOPC） as end-capper, and four polydiols, poly（tetramethylene glycol）s （PTMG）, polydimethylsiloxane （PDMS）, poly（1,6-hexyl-1,5-pentylcarbonate） （PHPC） and poly（propylene glycol） （PPG） as soft segments, respectively. The chemical structures of the synthesized polyurethanes were characterized by 1H-NMR and FTIR. DSC and DMA were employed to study the phase behavior of these novel polyurethanes due to their great influences on the surface properties, and hence their interactions with bio-systems. The results showed that phase separation of the fluorinated phosphatidylcholine end-capped polyurethanes was increased in comparison with that of normal polyurethanes. The effect of fluorinated phosphatidylcholine end-capped groups on the phase behavior was further demonstrated by analyzing the degree of hydrogen-bonding between hard and soft segments.展开更多
A series of random copolymers （PCLAs） were synthesized by ring-opening polymerization of D,L-lactide （LA） and ε-caprolactone （CL） with different molar ratios. PCLA based polyurethanes （PCLAUs） were obtained b...A series of random copolymers （PCLAs） were synthesized by ring-opening polymerization of D,L-lactide （LA） and ε-caprolactone （CL） with different molar ratios. PCLA based polyurethanes （PCLAUs） were obtained by chain-extending of PCLA and polytetramethylene ether （PTMEG） with hexamethylene diisocyanate （HDI）. All the PCLAUs exhibit good shape memory properties with high shape fixity ratios above 98% and shape recovery ratios above 82% in the first cycle and 91% in the second cycle. PCLAUs with less CL content show faster recovery speed and PCLAUs with more CL content show higher shape recovery ratio. The trigger temperature can be tuned or controlled around body temperature by adjusting the molar ratio of LA to CL. The PCLAUs have potential applications in implant biomedical devices, especially for minimally invasive deployable devices.展开更多
Thermoplastic poly(ether-ester-urethane)s were synthesized from poly(L-lactide) diols (PLLA diols), polytetrahydrofuran diol (PTMG diols), 4,4'-dicyclohexylmethane diisocyanate (HMDI), and 1,4-butanediol (BDO) by ...Thermoplastic poly(ether-ester-urethane)s were synthesized from poly(L-lactide) diols (PLLA diols), polytetrahydrofuran diol (PTMG diols), 4,4'-dicyclohexylmethane diisocyanate (HMDI), and 1,4-butanediol (BDO) by a two-step reaction, and the morphology and property of the resultant TPU could be adjusted by varying the PLLA contents. The soft segment was composed of PLLA and PTMG diols. By controlling the percentage of PLLA in the soft segment, the glass transition temperature and mechanical properties of the polyurethanes could be regulated. Based on the FTIR spectrum, we found that two kinds of hydrogen bonding existed individually in soft matrix and hard domain. The hydrogen bonding in soft matrix was unstable, which could be destroyed during elongation. With in situ stretching WAXS and SAXS experiments, we found that the PLLA crystal was destroyed and the PLLA domain oriented along the stretch direction. Finally, we proposed a schematic model to illustrate the microstructures of these elastomers before and after stretch.展开更多
基金supported by the National Natural Science Foundation of China(Nos.51603005,52403186 and 52573150)Fujian Provincial Natural Science Foundation of China(No.2024J011447)+1 种基金Natural Science Foundation of Xiamen,China(No.3502Z20227305)the Postdoctoral Fellowship Program of CPSF(No.GZC20240095)。
文摘Near-infrared(NIR)light-responsive shape memory polymers(SMPs)show great promise for biomedical applications,but conventional photothermal agents suffer from high cost,complex preparation,or poor biocompatibility,while lignin-based alternatives exhibit insufficient photothermal conversion efficiency.Herein,we developed a novel strategy to enhance photothermal performance of lignin through sequential demethylation modification and Fe^(3+)complexation for constructing NIR light responsive SMPs.Dealkaline lignin(DL)was first demethylated using iodocyclohexane to produce demethylated lignin(DDL)with increased catechol content,which was then incorporated into polycaprolactone-based polyurethane synthesis followed by Fe^(3+)complexation.Results showed that DDL-Fe^(3+)complexes have significantly enhanced photothermal conversion performance,and the resulting PU-DDL+Fe^(3+)polyurethane with 0.5 wt%DDL content demonstrated a temperature increases of 39.8℃under 0.33 W·cm-2808 nm NIR irradiation.This excellent photothermal performance enables the shape-fixed PU-DDL+Fe^(3+)polyurethane to rapidly recover to its initial shape under NIR light irradiation.Additionally,PU-DDL+Fe^(3+)polyurethane exhibits good mechanical properties and biocompatibility,demonstrating significant biomedical application potential.
基金financially supported by the Maoming Science and Technology Bureau(No.2022DZXHT007)。
文摘The synthesis of polyurethanes(PUs)from the reaction of low molecular weight poly(ethylene carbonate)diol(PECD)is rarely investigated.This work reports a novel PU with excellent mechanical properties from the solution polymerization of 4,4-diphenylmethane diisocyanate(MDI)with PECD that was derived from the copolymerization of carbon dioxide(CO_(2))and ethylene oxide(EO).The tensile strength,the elongation at break and 300%constant tensile strength of the PECD-PU were up to 66±2 MPa,880%±50%and 13 MPa,respectively,higher than the control PUs from the reaction of MDI with commercial polyethers or polyesters.The PECD-PU with high CO_(2) carbonate content exhibited good solvent resistance and chemical stability.Of importance,the mechanical properties and chemical resistance of PECD-PU were significantly enhanced with the increasing content of CO_(2),i.e.,the carbonate unit in PECD.This work provides comprehensive properties of PECD-derived PUs,indicating that PECD is a competitive precursor for the preparation of PU and has broad application prospects.
基金The National Natural Science Foundation of China(No.52173077)the Liaoning Provincial Department of Education Series Project(No.LJKZ0187)+1 种基金Natural Science Foundation of Liaoning Province(No.2023-MS-239)Liaoning BaiQianWan Talents Program(No.2021921081)。
文摘In this study,a facile method was employed to synthesize strong,yet highly elastic polyurethane-urea(PUU)with typical characteristics and 94% optical transmittance.Graphene platelets(GNPs)were prepared and modified via a scalable and eco-friendly mechanochemical approach.The produced GNPs is at 1.6-nm thickness with high electrical conductivity of~950 S/m.The structure-property relations of PUU/GNP nanocomposites were comprehensively investigated through morphology and mechanical properties measurements.The strong interface and high-density hydrogen bonds between modified GNPs(M-GNPs)and PUU significantly enhanced the mechanical properties of the PUU nanocomposite.The PUU composite showed 66.7%and 36.2%increments in tensile and impact strengths,respectively,at 0.2 wt% M-GNPs.The reversible hydrogen bond between M-GNPs and PUU endowed the nanocomposite with self-healing properties achieving 97.8% healing efficiency of the strength after 5 h at 120℃.This study demonstrates the importance of surface modification and provides a simple yet robust approach for preparing high-performance and functional PUU/graphene composites.
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funded by the LPDP-RIIM,Research Grant No.18/IV/KS/06/2022 and 4830/IT3.L1/PT.01.03/P/B/2022,titled Pengembangan Produk Oriented Strand Board Unggul dari Kayu Ringan dan Cepat Tumbuh dalam Rangka Pengembangan Produk Biokomposit Prospektif.
文摘Recent advancements in developing tannin-based non-isocyanate polyurethane(NIPU)resins have unlocked new possibilities for sustainable and eco-friendly wood adhesives.Unlike conventional polyurethane,NIPUs eliminate hazardous isocyanates,offering safer alternatives for industrial applications.Tannin,a naturally occurring polyphenolic compound,plays a pivotal role in enhancing these resins’fire-resistance and super-hydrophobic properties.This review highlights key developments in synthesizing tannin-based NIPU,focusing on various polymerization techniques such as polyaddition,polycondensation,ring-opening polymerization,and rearrangement.These strategies contribute to improved mechanical strength,thermal stability,and resistance to water absorption.Recent studies demonstrate that tannin-based NIPU adhesives meet or exceed international internal bonding strength,elasticity,and durability standards.Their application in wood-based composites like oriented strand boards(OSB)has shown promising results,offering improved resistance to moisture and superior dimensional stability.Furthermore,the cross-linked polymer network,supported by chemical modifications like the introduction of fluoroalkyl groups,significantly enhances hydrophobicity and fire retardancy.Despite these advancements,challenges remain in terms of scalability,cost,and integration with existing manufacturing processes.Future research should focus on optimizing reaction conditions,improving raw material availability,and developing industrial-scale production methods.This review underscores the potential of tannin-based NIPU resins as a viable and sustainable alternative for various wood composite applications.
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supported by the National Natural Science Foundation of China(No.51905543)。
文摘This study aimed to systematically regulate the performance of 4D printing composites by investigating the synergistic effects of dicumyl peroxide(DCP)and maleic anhydride-grafted polyethylene(MAH-g-PE)on a poly(lactic acid)/thermoplastic polyurethane(PLA/TPU)matrix.Specifically,using a 70 wt%/30 wt%PLA/TPU matrix and an L_(9)(3^(2))orthogonal design,composites were evaluated via morphology,shape memory,mechanical tests,and multi-criteria analysis.Moderate DCP enhanced crosslinking,improving storage modulus and thermal stability,while excessive DCP caused brittleness.Furthermore,MAH-g-PE effectively improved interfacial compatibility,and its synergy with DCP was dosage-dependent.Consequently,Sample 5 achieved optimal performance,exhibiting uniform fracture morphology,a shape fixation rate of98.8%with the fastest recovery,and balanced strength-ductility.Multi-criteria analysis identified elongation at break and recovery time as the top contributing factors,with consistent rankings validated by Spearman analysis(ρ=0.833,p<0.01).In summary,adjusting DCP and MAH-g-PE contents effectively modulates the crosslinking structure and interfacial properties of PLA/TPU composites,providing a viable strategy for developing high-performance,tunable 4D printing materials.
文摘Silane terminated prepolymers for adhesives, sealants and coatings are of <span style="font-family:"">great industrial importance. They are very important because of their low toxicity over polyurethanes, silicones, and solvent-based products. Hence, many pieces of literature which deal with the synthesis, properties and applications of this Silane terminated polymers hybrid system exist. Silylated polyether (MS polymers) and Silylated Polyurethane Polymers (SPUR) are the bases for numerous sealants, adhesives and coatings used worldwide. A hybrid system mixed with organic-polyurethane proportion and inorganic-alkoxysilane proportion combines the benefits of conventional polyurethane and silicone-based products. This article reviews the chemistry of MS polymers and SPUR and their advantages and disadvantages in silyl terminated prepolymer-based adhesives, sealants and coatings as well as provides information on different end applications.
基金financially supported by the National Natural Science Foundation of China(Nos.51333008,51273214 and 51073176)the project of key technological breakthrough for emerging industries of strategic importance(Nos.2011A091102001,and 2011A091102003)+2 种基金the Science and Technology Program of Guangdong Province(Nos.2010B010800021 and 2010A011300004)the Basic Scientific Research Foundation in Colleges and Universities of Ministry of Education of China(No.12lgjc08)the ST project of Hongyun Honghe Tobacco Group(No.HYHH2013YL06)
文摘Polyurethanes consisting of tri-functional homopolymer of hexamethylene diisocyanate （tri-HDI） and polyethylene glycol （PEG） are synthesized, in which photo-reversible coumarin moieties act as pendant groups. Accordingly, the polyurethanes can be repeatedly self-healed under UV lights at room temperature by taking advantages of the photodimerization and photocleavage habits of coumarin. Molecular weight of the soft segment, PEG, is found to be closely related to the healing performance of the polyurethanes. Lower molecular weight PEG that corresponds to higher initial coumarin concentration in the polymer is critical for obtaining higher healing efficiency in the case of the first healing action. Nevertheless, it does not guarantee high reversibility of the photo-remendability during the repeated healing events. In contrast, the polyurethane with moderate molecular weight PEG has achieved balanced performance. Reaction kinetics is less important for the healing effect.
基金supported by the National Natural Science Foundation of China(Nos.51073104 and 51173118)the Changjiang Scholars and Innovative Research Teams in Universities(No.IRT1163)the Sichuan Provincial Science Fund for Distinguished Young Scholars(No.09ZQ026-024)
文摘To better investigate the degradation and biocompatibility of waterborne biodegradable polyurethanes for tissue engineering, a series of new waterborne biodegradable polyurethanes （PEGPUs） with low degree of crosslinking was synthesized using IPDI, BDO and L-lysine as hard segments, PCL and PEG as soft segment. The bulk structures and properties of the prepared polyurethanes were characterized by Fourier transform infrared spectroscopy （FTIR）, differential scanning calorimetry （DSC）, tensile mechanical tests and water contact angle （WCA） measurements. The degree of microphase separation was slightly improved because of the lowered crosslinking degree of these PEGPUs in comparison with the high cross-linking degree samples, leading to good mechanical properties, as indicated by DSC and stress-strain data. Moreover, biodegradability of the polyurethanes was evaluated in phosphate buffer solutions （PBS） under different pH values and enzymatic solution at pH 7.4 through weight loss monitoring. The results suggested that the degradation of these PEGPUs was closely related to their bulk and surface properties. And the degradation products didn＇t show apparent inhibition effect against fibroblasts in vitro. These studies demonstrated that the waterborne biodegradable polyurethanes could find potential use in soft tissue engineering and tissue regeneration.
基金supported by the National Natural Science Foundation of China(No.20874040)Research Funds from University of Jinan(XKY0721)
文摘Polyurethanes（PU） were prepared using toluene diisocyanate,polypropylene glycol,ethylene glycol, dimethylolpropionic acid and triethylamine,and a siloxane modified PU（PSU） was obtained through reaction of the PU prepolymers with bis（3-（1-methoxy-2-hydroxypropoxy）propyl） terminated polysiloxanes（PMTS） of different molecular weight,specifically designed for this purpose.Results showed that,with increases in molecular weight of PMTS and its content,viscosity of the final PSU latexes decreased;phase separation of the incorporated PMTS in PSU films increased;the average particle sizes of the latexes varied between 110 nm and 330 nm,and the surface tension in the final latexes was relatively constant regardless of PMTS amount and its molecular weight.It was likely that copolymerized polysiloxanes had trend to enrich on top of the film when PMTS molecular weight was around 2000 and its content above 5 wt%.In general, PMTS modified polyurethane films showed higher performance than those from unmodified waterborne polyurethane latexes.
基金supported by the Open Fund of Key Laboratory of Road & Bridge and Underground Engineering of Gansu Province(No.Kfjj-10-05)"Qing Lan" Talent Engineering Funds by Lanzhou Jiaotong University(No.QL-08- 03A)
文摘Waterborne polyurethane composites containing silica nanoparticles are synthesized successfully via the in situ polymerization. The structure, thermal stability, surface hardness, tensile strength, UV-Vis absorbance, dynamic mechanical properties and chemicals resistance of the resulting composites are investigated by FTIR, TEM, TGA, UV-Vis, DMA and chemicals soakage measurements. Results show that polyurethane molecules and silica nanoparticles are linked with covalent bonds. As a result, physical properties of polyurethane composites, such as thermal stability, surface hardness, weather and chemicals resistance are all improved when an appropriate concentration of silica nanoparticles are incorporated.
基金financially supported by the National Natural Science Foundation of China (No. 51573114)the National Science Fund for Distinguished Young Scholars of China (No. 51425305)the Project of State Key Laboratory of Polymer Materials Engineering (Sichuan University) (No. SKLPME 2016-2-04)
文摘Thermomechanical properties of polyurethanes（PUs） strongly depend on the molecular interactions and microphase structure. In this work, two chain extenders with different ratios, flexile 1,4-butanediol（BDO） and branched trimethylolpropane mono allyl ether（TMPAE）, are used to tune the molecular interactions and microphase structures of a series of biodegradable thermoplastic polyurethanes（TPUs）. In TPUs, the biodegradable polycaprolactone（PCL, M_n of 2000） is used as soft segment while 1,6-diisocyanatohexane（HDI） and chain extenders are used as hard segment. Fourier transform infrared spectroscopy（FTIR）, proton nuclear magnetic resonance spectroscppy（~1 H-NMR）, gel permeation chromatography（GPC）, differential scanning calorimetry（DSC）, dynamic mechanical analysis（DMA） and mechanical tests were performed to characterize the bulk structure and properties of TPUs. Compared with BDO, the steric bulk of TMPAE is larger. The increment of TMPAE can help to increase the hydrogen bond content, microphase separation, and the elastic modulus ratio（R）, which would strongly affect the thermomechanical property of the TPUs. The results of this work verify the importance of the structure of chain extender on the properties of TPUs. It provides valuable information for further understanding the structure-property relationships of these polyurethanes.
基金financially supported by the National Natural Science Foundation of China(No.50673063)Program for the New-Century Excellent Talents of Ministry of Education of China(NCET-08-0381)Sichuan Provincial Science Fund for Distinguished Young Scholars(09ZQ026-024)
文摘A series of fluorinated phosphatidylcholine polyurethane macromolecular additives were synthesized by solution polymerization using methylenebis（phylene isocyanates） （MDI） and 1,4-butanediol （BDO） as hard segments, a new phoshporycholine, 2-（2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-10-（2-hydroxyethoxy）decyloxy） ethyl phosphorycholine （HDFOPC） as end-capper, and four polydiols, poly（tetramethylene glycol）s （PTMG）, polydimethylsiloxane （PDMS）, poly（1,6-hexyl-1,5-pentylcarbonate） （PHPC） and poly（propylene glycol） （PPG） as soft segments, respectively. The chemical structures of the synthesized polyurethanes were characterized by 1H-NMR and FTIR. DSC and DMA were employed to study the phase behavior of these novel polyurethanes due to their great influences on the surface properties, and hence their interactions with bio-systems. The results showed that phase separation of the fluorinated phosphatidylcholine end-capped polyurethanes was increased in comparison with that of normal polyurethanes. The effect of fluorinated phosphatidylcholine end-capped groups on the phase behavior was further demonstrated by analyzing the degree of hydrogen-bonding between hard and soft segments.
基金financially supported by the National Key Technology R&D Program(No.2012BAI17B05)
文摘A series of random copolymers （PCLAs） were synthesized by ring-opening polymerization of D,L-lactide （LA） and ε-caprolactone （CL） with different molar ratios. PCLA based polyurethanes （PCLAUs） were obtained by chain-extending of PCLA and polytetramethylene ether （PTMEG） with hexamethylene diisocyanate （HDI）. All the PCLAUs exhibit good shape memory properties with high shape fixity ratios above 98% and shape recovery ratios above 82% in the first cycle and 91% in the second cycle. PCLAUs with less CL content show faster recovery speed and PCLAUs with more CL content show higher shape recovery ratio. The trigger temperature can be tuned or controlled around body temperature by adjusting the molar ratio of LA to CL. The PCLAUs have potential applications in implant biomedical devices, especially for minimally invasive deployable devices.
基金financially supported by the National Key Research and Development Program of China (No. 2017YFB0309300)the National Natural Science Foundation of China (No. 51773218)+1 种基金Youth Innovation Promotion Association of CAS (No. 2018338)Ningbo Natural Science Foundation (No.2018A610109)
文摘Thermoplastic poly(ether-ester-urethane)s were synthesized from poly(L-lactide) diols (PLLA diols), polytetrahydrofuran diol (PTMG diols), 4,4'-dicyclohexylmethane diisocyanate (HMDI), and 1,4-butanediol (BDO) by a two-step reaction, and the morphology and property of the resultant TPU could be adjusted by varying the PLLA contents. The soft segment was composed of PLLA and PTMG diols. By controlling the percentage of PLLA in the soft segment, the glass transition temperature and mechanical properties of the polyurethanes could be regulated. Based on the FTIR spectrum, we found that two kinds of hydrogen bonding existed individually in soft matrix and hard domain. The hydrogen bonding in soft matrix was unstable, which could be destroyed during elongation. With in situ stretching WAXS and SAXS experiments, we found that the PLLA crystal was destroyed and the PLLA domain oriented along the stretch direction. Finally, we proposed a schematic model to illustrate the microstructures of these elastomers before and after stretch.
