The aim of this research work was to evaluate the potential of using renewable natural feedstock,i.e.,Jatropha curcas oil(JCO)for the synthesis of non-isocyanate polyurethane(NIPU)resin for wood composite applications...The aim of this research work was to evaluate the potential of using renewable natural feedstock,i.e.,Jatropha curcas oil(JCO)for the synthesis of non-isocyanate polyurethane(NIPU)resin for wood composite applications.Commercial polyurethane(PU)is synthesized through a polycondensation reaction between isocyanate and poly-ol.However,utilizing toxic and unsustainable isocyanates for obtaining PU could contribute to negative impacts on the environment and human health.Therefore,the development of PU from eco-friendly and sustainable resources without the isocyanate route is required.In this work,tetra-n-butyl ammonium bromide was used as the activator to open the epoxy ring with 3-Aminopropyltriethoxisylane as a catalyst to yield urethane of JCO(UJCO).The UJCO were characterized by Fourier Transform Infra-Red spectroscopy(FTIR)and their oxirane,and hydroxyl values were measured.The result showed that a decrease in oxirane value was found while the hydroxyl value was increased during the time,confirming that the urethane group was formed.The presence of functional groups in FTIR spectra at wave numbers 1732.08,1562.34,and 3348.42 cm^(−1) indicates the functional groups of C=O(urethane carbonyl),–NH,and–OH,respectively confirmed this finding.The potential applications of NIPU in the wood composite were also outlined.展开更多
The reaction of a desulphurized kraft lignin with hexamethylene diamine and dimethyl carbonate has allowed the development of isocyanate-free polyurethane resins.The present research work is based on previous studies ...The reaction of a desulphurized kraft lignin with hexamethylene diamine and dimethyl carbonate has allowed the development of isocyanate-free polyurethane resins.The present research work is based on previous studies made with hydrolyzable and condensed tannins,but takes advantage of the higher number of hydroxyl groups present in lignin and their different aliphatic and aromatic character.The obtained materials were analyzed by Fourier transform infrared(FTIR)spectroscopy,matrix-assisted laser desorption ionization time-of-flight(MALDI-TOF)mass spectrometry and solid-state cross-polarization/magic angle spinning(CP MAS)13C nuclear magnetic resonance(NMR),which have revealed the presence of urethane functions.The interpretation of the results has shown a larger number of species than when tannins were used and has indicated the presence of two types of bonds in the new molecules formed:ionic and covalent bonds.展开更多
The improvement of biocompatibility of polyurethanes was investigated.The results demonstrate that the blood compatibility of polyurethanes can be further improved by just simply mixing with the fluorinated phosphatid...The improvement of biocompatibility of polyurethanes was investigated.The results demonstrate that the blood compatibility of polyurethanes can be further improved by just simply mixing with the fluorinated phosphatidylcholine poly(carbonate urethane)s(FPCPCUs).The solution blending was done by mixing poly(ether urethane)(PEU)with FPCPCU in different compositions.An increased blood compatibility of the blend films was observed with the increase of FPCPCU content,and when FPCPCU content reached to 40 wt%(40F...展开更多
The surface phase separated structure of polyurethanes is always desired due to the advantage of better biocompatibility, compared with the homogeneous one. The key issue is how to control and characterize the surface...The surface phase separated structure of polyurethanes is always desired due to the advantage of better biocompatibility, compared with the homogeneous one. The key issue is how to control and characterize the surface morphology. In this work, we report the uppermost surface morphology of fluorinated poly(carbonate urethane)s with fluorinated side chains attached to hard segments as studied by AFM, XPS and contact angle measurement. A self-assembled micro-domain with the fluorinated side chain standing up on the uppermost surface has been proposed for polyurethane with higher fluorinated content, based on the result obtained.展开更多
The crystalline behavior of urethane substitute polydiacetylene was studied by using pohrized light and electron microscopy. The lamellar morphological structure was observed in the crystallized films. The thickness o...The crystalline behavior of urethane substitute polydiacetylene was studied by using pohrized light and electron microscopy. The lamellar morphological structure was observed in the crystallized films. The thickness of lamellae is about 300A, being independent of the crystalline temperature. But the size and density of lamellae were dependent on the crystallization temperature. If the molten film was sheared during the crystallzation process the oriented lamellae grew with their long axes perpendicular to the direction of shear and the chain direction was normal to the lamellar surface.展开更多
The urethane acrylate(UA) was made of poly(tetramethylenc oxide), 4,4’-diphenylmethane diisocyanate, and 2-hydroxyethyl methacrylate. A series of poly(methyl methacrylate) / urethane acrylate copolymers was prepared ...The urethane acrylate(UA) was made of poly(tetramethylenc oxide), 4,4’-diphenylmethane diisocyanate, and 2-hydroxyethyl methacrylate. A series of poly(methyl methacrylate) / urethane acrylate copolymers was prepared by using a redox initiating system. The copolymers had cross linked structures and two-phase morphologies as indicated by the results of the dynamic mechanical measurement and swelling test.展开更多
A novel polycarbonate urethane was synthesized by the two-stage solution process of diisocyanates with polycarbonate diols(PCDL),in which PCDL,1,4-butanediol(BD) and mixture of 4,4'-methylenediphenyl diisocy-anate...A novel polycarbonate urethane was synthesized by the two-stage solution process of diisocyanates with polycarbonate diols(PCDL),in which PCDL,1,4-butanediol(BD) and mixture of 4,4'-methylenediphenyl diisocy-anate and hexamethylene diisocyanate(HDI) were soft segment,chain extender and rigid segment,respectively.The structures were characterized by using FTIR and 1H-NMR.The thermoanalysis and mechanical properties of products were measured by means of DSC,TG and other systems.The result shows that an important technological thrust is the development of polymeric materials with improved mechanical characteristics.With the increase in content of HDI component,the elongation at break point increases quickly and decomposition temperature decreases.The DSC/TG curves indicate that a phase division exists in the structure of polycarbonate urethanes.Thermal decomposition occurs at two temperature levels because their rigid and soft chain segments correspond to different glass transition domains,respectively.This paper demonstrates that the mechanical properties of polycarbonate urethane can be controlled by changing the ratio of raw materials.展开更多
A polymer soft actuator is under investigation using a poly urethane elastomer film that bends by means of an applied voltage, which is based on the electrostriction. Bending experiments were performed under different...A polymer soft actuator is under investigation using a poly urethane elastomer film that bends by means of an applied voltage, which is based on the electrostriction. Bending experiments were performed under different metal electrodes deposited the both sides of the film. Even if the thickness of the both electrodes?is the same, the metal of the both electrodes?is desirable to be the same to bend more. It is suggested that the balance of the physical properties of the both metal is critical for larger bending.展开更多
We are investigating a polymer soft actuator using a poly urethane elastomer film that bends by an applied voltage, which is based on the electrostriction. In this article, the bending magnitude was studied in a weigh...We are investigating a polymer soft actuator using a poly urethane elastomer film that bends by an applied voltage, which is based on the electrostriction. In this article, the bending magnitude was studied in a weight-loaded condition. It was found that the thinner film can bend the more without any load, but that the film of 200-μm thickness gave the largest bending when weights were loaded. The thickness of some degree is critical for large bending torque.展开更多
The Acrylic urethane paint produced by the Red Lion Paint Company is a kind of dual constituent resin paint solidified at room temperature. It can achieve a good film of paint and is widely used as coating for automob...The Acrylic urethane paint produced by the Red Lion Paint Company is a kind of dual constituent resin paint solidified at room temperature. It can achieve a good film of paint and is widely used as coating for automobiles, motorcycles, locomotives, aeroplanes, ships, bridges, steel chimneys, and large outdoor facilities and installations. One of the constitutents is acrylic urethane carbonyl, and the additives of paint, assistants, and solvent. The other is fatty group cyanate. The main products include a second substratum paint of acrylic urethane and acrylic urethane enamel paint, and dead lustre and semi-展开更多
Covalent adaptable networks(CANs),which share the properties of both thermosets and thermoplastics at the same time,are desirable for many applications.Introducing bulky substituents is a feasible way to design dynami...Covalent adaptable networks(CANs),which share the properties of both thermosets and thermoplastics at the same time,are desirable for many applications.Introducing bulky substituents is a feasible way to design dynamic covalent bonds for constructing CANs,as evidenced by the successful implementation in CANs based on hindered urea bonds(HUBs).However,the dynamicity induced by introducing bulky substituents always come with low bond energy,resulting in low mechanical strength and poor stability of the CANs.Herein,we designed a novel hindered urethane bond,which is weak in thermodynamic(K_(eq)=1701.23 L/mol at 25℃)and inert in kinetic at low temperature,but stable in thermodynamic(K_(eq)=1.54×10^(4) L/mol at 100℃)and active in kinetic at high temperature(k_(-1)=0.105 h^(-1) at 80℃ and 0.315 h^(-1) at 120℃).As a result,the polyurethane based on it exhibits high mechanical properties(with Youngs’modulus of 1011±29MPa and flexible modulus reached 1833±50MPa)and excellent reversibility(can be reprocessed at 60℃ under 100 kPa in 30 min and completely healed at 40℃ in 10 min).Moreover,unlike to many CANs based on hindered urea bonds,our dynamic polyurethanes are highly stable in humid environment or even water solutions due to the slow hydrolysis kinetics.Such highperformance dynamic polyurethane polymers are attractive for many applications.展开更多
A simple non-isocyanate route is developed for synthesizing crystallizable aliphatic thermoplastic poly(ester urethane) elastomers (TPEURs) with good thermal and mechanical properties. Three prepolymers of 1,6-bis...A simple non-isocyanate route is developed for synthesizing crystallizable aliphatic thermoplastic poly(ester urethane) elastomers (TPEURs) with good thermal and mechanical properties. Three prepolymers of 1,6-bis(hydroxyethyloxycarbonylamino) hexane (BHCH), i.e. PrePBHCHs, were prepared through the self-transurethane polycondensation of BHCH. A poly(butylene adipate) prepolymer (PrePBA) with terminal HO-- groups was prepared and used as a polyester glycol. A series of TPEURs were prepared by the co-polycondensation of the PrePBHCHs with PrePBA at 170 ℃under a reduced pressure of 399 Pa. The TPEURs were characterized by gel permeation chromatography, FTIR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, atomic force microscopy, and tensile test. The TPEURs exhibited Mn up to 23300 g/mol, Mw up to 51100 g/mol, Tg ranging from -33.8 ℃ to -3.1 ℃, Tm from 94.3 ℃ to 111.9 ℃, initial decomposition temperature over 274.7℃, tensile strength up to18.8 MPa with a strain at break of 450.0%, and resilience up to 77.5%. TPU elastomers with good crystallization and mechanical properties were obtained through a non-isocyanate route.展开更多
Temperature-accelerated in vitro degradation was established to estimate the longevity of polyurethane applied for long-term implantation.However,the prediction did not correlate well with the data from clinical expla...Temperature-accelerated in vitro degradation was established to estimate the longevity of polyurethane applied for long-term implantation.However,the prediction did not correlate well with the data from clinical explants and the rationality of accelerated in vitro test is still in a controversial due to the deviation.To improve the accuracy of the in vitro prediction,the influence of hydrogen bonding(HB)on the accelerated hydrolysis of silicone based polyetherurethans(SPEUs)extended with three side chains.Combining the temperature-controlled FTIR and the physical properties after temperature-accelerated in vitro degradation,it was demonstrated that side chain could increase the degree of hydrogen bond dissociation at higher temperature,resulting in the decrease of the calculated activation energy(E_(a))of hydrolysis.At low temperatures,changes in surface morphology and molar mass of PEUs are minimal and HB are less easily dissociated,which had barely impact on the hydrolysis resistance.It was proposed that the E_(a) will not be impacted and that the accuracy of prediction will be increased if the acceleration temperature is lower than 70℃ and HB change is less than 15%.展开更多
A non-isocyanate route for synthesizing thermoplastic polyurethanes with excellent thermal and mechanical properties was described. Melt transurethane polycondensation of 1,6-bis(hydroxyethyloxy carbonyl amino)hexan...A non-isocyanate route for synthesizing thermoplastic polyurethanes with excellent thermal and mechanical properties was described. Melt transurethane polycondensation of 1,6-bis(hydroxyethyloxy carbonyl amino)hexane with four poly(ethylene glycol)s (PEGs), i.e. PEG400, PEG600, PEG1000, or PEG1500, was conducted at different molar ratios. A series of thermoplastic poly(ether urethane)s (TPEUs) with long PEG sequences were prepared. The TPEUs were characterized via gel permeation chromatography, FTIR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray scattering, and tensile tests. The TPEUs exhibit Tg between 12.4 ℃ and -40.4 ℃, Tm of up to 149.8 ℃, and initial decomposition temperature over 239.4 ℃. The tensile strength of the TPEUs reaches 38.39 MPa with a strain at break of 852.92%.展开更多
Polylactide (PLA) was successfully toughened by blending with bio-based poly(ester)urethane (TPU) elastomers which contained bio-based polyester soft segments synthesized from biomass diols and diacids. The misc...Polylactide (PLA) was successfully toughened by blending with bio-based poly(ester)urethane (TPU) elastomers which contained bio-based polyester soft segments synthesized from biomass diols and diacids. The miscibility, mechanical properties, phase morphology and toughening mechanism of the blend were investigated. Both DSC and DMTA results manifested that the addition of TPU elastomer not only accelerated the crystallization rate, but also increased the final degree of crystallinity, which proved that TPU has limited miscibility with PLA and has functioned as a plasticizer. All the blend samples showed distinct phase separation phenomenon with sea-island structure under SEM observation and the rubber particle size in the PLA matrix increased with the increased contents of TPU. The mechanical property variation of PLA/TPU blends could be quantitatively explained by Wu's model. With the variation of TPU, a brittle-ductile transition has been observed for the TPU/PLA blends. When these blends were under tensile stress conditions, the TPU particles could be debonded from the PLA matrix and the blends showed a high ability to induce large area plastic deformation before break, which was important for the dissipation of the breaking energy. Such mechanism was demonstrated by tensile tests and scanning electron microcopy (SEM) observations.展开更多
There have been studies on the structure and properties of segmented polyetherurethane (SPEU)based on polytetramethylene glycol (PTMG)/4, 4′-diphenylmethane diisoeyanate (MDI)/1,4-butandiol (BD). It was shown that on...There have been studies on the structure and properties of segmented polyetherurethane (SPEU)based on polytetramethylene glycol (PTMG)/4, 4′-diphenylmethane diisoeyanate (MDI)/1,4-butandiol (BD). It was shown that only sufficient long hard segment (MDI/BD) domains could crystallize under certain conditions, while the shorter hard domains (hard segment in the SPEU with 1000 n PTMG and mole展开更多
Molecular recognition and fluorescent sensing of Group 2A carcinogen-urethane was achieved in aqueous solution. The molecular sensors are the endo-functionalized molecular tubes with amide protons in the hydrophobic c...Molecular recognition and fluorescent sensing of Group 2A carcinogen-urethane was achieved in aqueous solution. The molecular sensors are the endo-functionalized molecular tubes with amide protons in the hydrophobic cavity.~1H NMR, fluorescence, and ITC titrations and single crystal X-ray crystallography reveal the binding stoichiometry, the binding affinities, and the driving forces. The binding is mainly driven by the hydrophobic effect through releasing the "high-energy" cavity water with minor contribution from hydrogen bonding. In addition, the syn-configured molecular tube was found to be a good fluorescent sensor for urethane in water(concentration range: 6.2–60 mmol/L) and in beer(concentration range: 22.9–60 mmol/L).展开更多
Polycarbonate urethane(PCU)nano-fibers were fabricated via electrospinning using N,Ndimethylformamide(DMF)and tetrahydrofuran(THF)as the mixed solvent.The effect of volume ratios of DMF and THF in the mixed solvent on...Polycarbonate urethane(PCU)nano-fibers were fabricated via electrospinning using N,Ndimethylformamide(DMF)and tetrahydrofuran(THF)as the mixed solvent.The effect of volume ratios of DMF and THF in the mixed solvent on the fiber structures was investigated.The results show that nano-fibers with a narrow diameter distribution and a few defects were obtained when mixed solvent with the appropriate volume ratio of DMF and THF as 1∶1.When the proportion of DMF was more than 75%in the mixed solvent,it was easy to form many beaded fibers.The applied voltage in the electrospinning process has a significant influence on the morphology of fibers.When the electric voltage was set between 22 and 32 kV,the average diameters of the fibers were found between 420 and 570 nm.Scanning electron microscopy(SEM)images showed that fiber diameter and structural morphology of the electrospun PCU membranes are a function of the polymer solution concentration.When the concentration of PCU solution was 6.0 wt-%,a beaded-fiber microstructure was obtained.With increasing the concentration of PCU solutions above 6.0 wt-%,beaded fiber decreased and finally disappeared.However,when the PCU concentration was over 14.0 wt-%,the average diameter of fibers became large,closed to 2μm,because of the high solution viscosity.The average diameter of nanofibers increased linearly with increasing the volume flow rate of the PCU solution(10.0 wt-%)when the applied voltagewas 24 kV.The results show that the morphology of PCU fibers could be controlled by electrospinning parameters,such as solution concentration,electric voltage and flow rate.展开更多
Mismatched biomechanical properties between artificial vascular grafts and native blood vessels can result in intimal hyperplasia,especially for the implantation of small-diameter blood vessels.Ideal biomaterials for ...Mismatched biomechanical properties between artificial vascular grafts and native blood vessels can result in intimal hyperplasia,especially for the implantation of small-diameter blood vessels.Ideal biomaterials for vascular repair still remain challenged.Biodegradable poly(ε-caprolactone)(PCL)has been applied for the preparation of electrospun vascular grafts,but more efforts are needed to improve its compliance with tissue growth.Herein,L-arginine-based poly(ester urethane)urea(PEUU)with both elasticity and biodegradability was synthesized so as to enhance the biomechanical properties of vascular grafts by blending electrospinning with PCL in a given mass ratio.It was exhibited that the prepared electrospun PCL/PEUU fibrous membranes were suitable for cell proliferation with normal cell morphology.More importantly,the electrospun membrane with 1/1 mass ratio of PCL/PEUU(PEUU50)showed specific flexibility,exhibiting more suitable mechanical properties matching to the native blood vessels.Specifically,the PEUU50 electrospun membrane demonstrated significantly lower Young’s modulus(9.3±0.8 MPa)and tensile strength(6.0±0.5 MPa),and extremely higher elongation(389%±24%)in wet state than those(16.3±3.0 MPa,11.4±7.1 MPa and 196%±57%,respectively)of the pristine PCL membrane.Overall,this study demonstrated the great potential of amino acid-based PEUUs for the application in small-diameter vascular grafts.展开更多
Polyurethanes are widely used in interventional devices due to the excellent physicochemical property.However,non-specific adhesion and severe inflammatory response of ordinary polyurethanes may lead to severe complic...Polyurethanes are widely used in interventional devices due to the excellent physicochemical property.However,non-specific adhesion and severe inflammatory response of ordinary polyurethanes may lead to severe complications of intravenous devices.Herein,a novel phospholipid-based polycarbonate urethanes(PCUs)were developed via two-step solution polymerization by direct synthesis based on functional raw materials.Furthermore,PCUs were coated on biomedical metal sheets to construct biomimetic anti-fouling surface.The results of stress–strain curves exhibited excellent tensile properties of PCUs films.Differential scanning calorimetry results indicated that the microphase separation of such PCUs polymers could be well regulated by adjusting the formulation of chain extender,leading to different biological response.In vitro blood compatibility tests including bovine serum albumin adsorption,fibrinogen adsorption and denaturation,platelet adhesion and whole-blood experiment showed superior performance in inhibition non-specific adhesion of PCUs samples.Endothelial cells and smooth muscle cells culture tests further revealed a good anti-cell adhesion ability.Finally,animal experiments including ex vivo blood circulation and subcutaneous inflammation animal experiments indicated a strong ability in anti-thrombosis and histocompatibility.These results high light the strong anti-adhesion property of phospholipid-based PCUs films,which may be applied to the blood-contacting implants such as intravenous catheter or antithrombotic surface in the future.展开更多
文摘The aim of this research work was to evaluate the potential of using renewable natural feedstock,i.e.,Jatropha curcas oil(JCO)for the synthesis of non-isocyanate polyurethane(NIPU)resin for wood composite applications.Commercial polyurethane(PU)is synthesized through a polycondensation reaction between isocyanate and poly-ol.However,utilizing toxic and unsustainable isocyanates for obtaining PU could contribute to negative impacts on the environment and human health.Therefore,the development of PU from eco-friendly and sustainable resources without the isocyanate route is required.In this work,tetra-n-butyl ammonium bromide was used as the activator to open the epoxy ring with 3-Aminopropyltriethoxisylane as a catalyst to yield urethane of JCO(UJCO).The UJCO were characterized by Fourier Transform Infra-Red spectroscopy(FTIR)and their oxirane,and hydroxyl values were measured.The result showed that a decrease in oxirane value was found while the hydroxyl value was increased during the time,confirming that the urethane group was formed.The presence of functional groups in FTIR spectra at wave numbers 1732.08,1562.34,and 3348.42 cm^(−1) indicates the functional groups of C=O(urethane carbonyl),–NH,and–OH,respectively confirmed this finding.The potential applications of NIPU in the wood composite were also outlined.
文摘The reaction of a desulphurized kraft lignin with hexamethylene diamine and dimethyl carbonate has allowed the development of isocyanate-free polyurethane resins.The present research work is based on previous studies made with hydrolyzable and condensed tannins,but takes advantage of the higher number of hydroxyl groups present in lignin and their different aliphatic and aromatic character.The obtained materials were analyzed by Fourier transform infrared(FTIR)spectroscopy,matrix-assisted laser desorption ionization time-of-flight(MALDI-TOF)mass spectrometry and solid-state cross-polarization/magic angle spinning(CP MAS)13C nuclear magnetic resonance(NMR),which have revealed the presence of urethane functions.The interpretation of the results has shown a larger number of species than when tannins were used and has indicated the presence of two types of bonds in the new molecules formed:ionic and covalent bonds.
基金This work was financially supported by the National Natural Science Foundation of China(Nos.50673063 and 50533050)Young Foundation of Sichuan University for Financial Support.This work was also subsidized by the Special Funds for Major State Basic Research Projects of China(No.2003CB615600).
文摘The improvement of biocompatibility of polyurethanes was investigated.The results demonstrate that the blood compatibility of polyurethanes can be further improved by just simply mixing with the fluorinated phosphatidylcholine poly(carbonate urethane)s(FPCPCUs).The solution blending was done by mixing poly(ether urethane)(PEU)with FPCPCU in different compositions.An increased blood compatibility of the blend films was observed with the increase of FPCPCU content,and when FPCPCU content reached to 40 wt%(40F...
基金This work was supported by the China National Distinguished Young Investigator Fund (29925413) and the NationalNatural Science Foundation of China (Project number 50303014).
文摘The surface phase separated structure of polyurethanes is always desired due to the advantage of better biocompatibility, compared with the homogeneous one. The key issue is how to control and characterize the surface morphology. In this work, we report the uppermost surface morphology of fluorinated poly(carbonate urethane)s with fluorinated side chains attached to hard segments as studied by AFM, XPS and contact angle measurement. A self-assembled micro-domain with the fluorinated side chain standing up on the uppermost surface has been proposed for polyurethane with higher fluorinated content, based on the result obtained.
文摘The crystalline behavior of urethane substitute polydiacetylene was studied by using pohrized light and electron microscopy. The lamellar morphological structure was observed in the crystallized films. The thickness of lamellae is about 300A, being independent of the crystalline temperature. But the size and density of lamellae were dependent on the crystallization temperature. If the molten film was sheared during the crystallzation process the oriented lamellae grew with their long axes perpendicular to the direction of shear and the chain direction was normal to the lamellar surface.
文摘The urethane acrylate(UA) was made of poly(tetramethylenc oxide), 4,4’-diphenylmethane diisocyanate, and 2-hydroxyethyl methacrylate. A series of poly(methyl methacrylate) / urethane acrylate copolymers was prepared by using a redox initiating system. The copolymers had cross linked structures and two-phase morphologies as indicated by the results of the dynamic mechanical measurement and swelling test.
基金Supported by International Cooperation from Ministry of Science and Technology of China (No.2008DFA51170)Program for New Century Excellent Talents (NCET) in University,Ministry of Education,China,and Scientific Research Foundation for Returned Overseas Chinese Scholars,Ministry of Education,China
文摘A novel polycarbonate urethane was synthesized by the two-stage solution process of diisocyanates with polycarbonate diols(PCDL),in which PCDL,1,4-butanediol(BD) and mixture of 4,4'-methylenediphenyl diisocy-anate and hexamethylene diisocyanate(HDI) were soft segment,chain extender and rigid segment,respectively.The structures were characterized by using FTIR and 1H-NMR.The thermoanalysis and mechanical properties of products were measured by means of DSC,TG and other systems.The result shows that an important technological thrust is the development of polymeric materials with improved mechanical characteristics.With the increase in content of HDI component,the elongation at break point increases quickly and decomposition temperature decreases.The DSC/TG curves indicate that a phase division exists in the structure of polycarbonate urethanes.Thermal decomposition occurs at two temperature levels because their rigid and soft chain segments correspond to different glass transition domains,respectively.This paper demonstrates that the mechanical properties of polycarbonate urethane can be controlled by changing the ratio of raw materials.
文摘A polymer soft actuator is under investigation using a poly urethane elastomer film that bends by means of an applied voltage, which is based on the electrostriction. Bending experiments were performed under different metal electrodes deposited the both sides of the film. Even if the thickness of the both electrodes?is the same, the metal of the both electrodes?is desirable to be the same to bend more. It is suggested that the balance of the physical properties of the both metal is critical for larger bending.
文摘We are investigating a polymer soft actuator using a poly urethane elastomer film that bends by an applied voltage, which is based on the electrostriction. In this article, the bending magnitude was studied in a weight-loaded condition. It was found that the thinner film can bend the more without any load, but that the film of 200-μm thickness gave the largest bending when weights were loaded. The thickness of some degree is critical for large bending torque.
文摘The Acrylic urethane paint produced by the Red Lion Paint Company is a kind of dual constituent resin paint solidified at room temperature. It can achieve a good film of paint and is widely used as coating for automobiles, motorcycles, locomotives, aeroplanes, ships, bridges, steel chimneys, and large outdoor facilities and installations. One of the constitutents is acrylic urethane carbonyl, and the additives of paint, assistants, and solvent. The other is fatty group cyanate. The main products include a second substratum paint of acrylic urethane and acrylic urethane enamel paint, and dead lustre and semi-
基金supported by the National Natural Science Foundation of China(No.22271139)the Fundamental Research Funds for the Central Universities(No.020514380294).
文摘Covalent adaptable networks(CANs),which share the properties of both thermosets and thermoplastics at the same time,are desirable for many applications.Introducing bulky substituents is a feasible way to design dynamic covalent bonds for constructing CANs,as evidenced by the successful implementation in CANs based on hindered urea bonds(HUBs).However,the dynamicity induced by introducing bulky substituents always come with low bond energy,resulting in low mechanical strength and poor stability of the CANs.Herein,we designed a novel hindered urethane bond,which is weak in thermodynamic(K_(eq)=1701.23 L/mol at 25℃)and inert in kinetic at low temperature,but stable in thermodynamic(K_(eq)=1.54×10^(4) L/mol at 100℃)and active in kinetic at high temperature(k_(-1)=0.105 h^(-1) at 80℃ and 0.315 h^(-1) at 120℃).As a result,the polyurethane based on it exhibits high mechanical properties(with Youngs’modulus of 1011±29MPa and flexible modulus reached 1833±50MPa)and excellent reversibility(can be reprocessed at 60℃ under 100 kPa in 30 min and completely healed at 40℃ in 10 min).Moreover,unlike to many CANs based on hindered urea bonds,our dynamic polyurethanes are highly stable in humid environment or even water solutions due to the slow hydrolysis kinetics.Such highperformance dynamic polyurethane polymers are attractive for many applications.
基金financially supported by the National Natural Science Foundation of China(Nos.21244006 and 50873013)
文摘A simple non-isocyanate route is developed for synthesizing crystallizable aliphatic thermoplastic poly(ester urethane) elastomers (TPEURs) with good thermal and mechanical properties. Three prepolymers of 1,6-bis(hydroxyethyloxycarbonylamino) hexane (BHCH), i.e. PrePBHCHs, were prepared through the self-transurethane polycondensation of BHCH. A poly(butylene adipate) prepolymer (PrePBA) with terminal HO-- groups was prepared and used as a polyester glycol. A series of TPEURs were prepared by the co-polycondensation of the PrePBHCHs with PrePBA at 170 ℃under a reduced pressure of 399 Pa. The TPEURs were characterized by gel permeation chromatography, FTIR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, atomic force microscopy, and tensile test. The TPEURs exhibited Mn up to 23300 g/mol, Mw up to 51100 g/mol, Tg ranging from -33.8 ℃ to -3.1 ℃, Tm from 94.3 ℃ to 111.9 ℃, initial decomposition temperature over 274.7℃, tensile strength up to18.8 MPa with a strain at break of 450.0%, and resilience up to 77.5%. TPU elastomers with good crystallization and mechanical properties were obtained through a non-isocyanate route.
基金financially supported by the National Natural Science Foundation of China(No.51973134)the State Key Research Development Program of China(No.2020YFC1107000)+1 种基金the NSAF(No.U1930204)Interdisciplinary Innovation Projects of West China Hospital of Stomatology Sichuan University(No.RD-03-202001)。
文摘Temperature-accelerated in vitro degradation was established to estimate the longevity of polyurethane applied for long-term implantation.However,the prediction did not correlate well with the data from clinical explants and the rationality of accelerated in vitro test is still in a controversial due to the deviation.To improve the accuracy of the in vitro prediction,the influence of hydrogen bonding(HB)on the accelerated hydrolysis of silicone based polyetherurethans(SPEUs)extended with three side chains.Combining the temperature-controlled FTIR and the physical properties after temperature-accelerated in vitro degradation,it was demonstrated that side chain could increase the degree of hydrogen bond dissociation at higher temperature,resulting in the decrease of the calculated activation energy(E_(a))of hydrolysis.At low temperatures,changes in surface morphology and molar mass of PEUs are minimal and HB are less easily dissociated,which had barely impact on the hydrolysis resistance.It was proposed that the E_(a) will not be impacted and that the accuracy of prediction will be increased if the acceleration temperature is lower than 70℃ and HB change is less than 15%.
基金financially supported by the National Natural Science Foundation of China(Nos.21244006 and 50873013)
文摘A non-isocyanate route for synthesizing thermoplastic polyurethanes with excellent thermal and mechanical properties was described. Melt transurethane polycondensation of 1,6-bis(hydroxyethyloxy carbonyl amino)hexane with four poly(ethylene glycol)s (PEGs), i.e. PEG400, PEG600, PEG1000, or PEG1500, was conducted at different molar ratios. A series of thermoplastic poly(ether urethane)s (TPEUs) with long PEG sequences were prepared. The TPEUs were characterized via gel permeation chromatography, FTIR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray scattering, and tensile tests. The TPEUs exhibit Tg between 12.4 ℃ and -40.4 ℃, Tm of up to 149.8 ℃, and initial decomposition temperature over 239.4 ℃. The tensile strength of the TPEUs reaches 38.39 MPa with a strain at break of 852.92%.
文摘Polylactide (PLA) was successfully toughened by blending with bio-based poly(ester)urethane (TPU) elastomers which contained bio-based polyester soft segments synthesized from biomass diols and diacids. The miscibility, mechanical properties, phase morphology and toughening mechanism of the blend were investigated. Both DSC and DMTA results manifested that the addition of TPU elastomer not only accelerated the crystallization rate, but also increased the final degree of crystallinity, which proved that TPU has limited miscibility with PLA and has functioned as a plasticizer. All the blend samples showed distinct phase separation phenomenon with sea-island structure under SEM observation and the rubber particle size in the PLA matrix increased with the increased contents of TPU. The mechanical property variation of PLA/TPU blends could be quantitatively explained by Wu's model. With the variation of TPU, a brittle-ductile transition has been observed for the TPU/PLA blends. When these blends were under tensile stress conditions, the TPU particles could be debonded from the PLA matrix and the blends showed a high ability to induce large area plastic deformation before break, which was important for the dissipation of the breaking energy. Such mechanism was demonstrated by tensile tests and scanning electron microcopy (SEM) observations.
文摘There have been studies on the structure and properties of segmented polyetherurethane (SPEU)based on polytetramethylene glycol (PTMG)/4, 4′-diphenylmethane diisoeyanate (MDI)/1,4-butandiol (BD). It was shown that only sufficient long hard segment (MDI/BD) domains could crystallize under certain conditions, while the shorter hard domains (hard segment in the SPEU with 1000 n PTMG and mole
基金financially supported by the National Natural Science Foundation of China (Nos. 21572097, 21772083 and 21822104)the SZSTI (Nos. JCYJ20170307105848463 and KQJSCX20170728162528382)
文摘Molecular recognition and fluorescent sensing of Group 2A carcinogen-urethane was achieved in aqueous solution. The molecular sensors are the endo-functionalized molecular tubes with amide protons in the hydrophobic cavity.~1H NMR, fluorescence, and ITC titrations and single crystal X-ray crystallography reveal the binding stoichiometry, the binding affinities, and the driving forces. The binding is mainly driven by the hydrophobic effect through releasing the "high-energy" cavity water with minor contribution from hydrogen bonding. In addition, the syn-configured molecular tube was found to be a good fluorescent sensor for urethane in water(concentration range: 6.2–60 mmol/L) and in beer(concentration range: 22.9–60 mmol/L).
基金This work has been financially supported by Program for New Century Excellent Talents in University“NCET,”NCET-07-0596Ministry of Education ofChina,by the International Cooperation from Ministry of Science and Technology of China(Grant No.2008DFA51170)by the Scientific Research Foundation for the Returned Overseas Chinese Scholars,State Education Ministry.
文摘Polycarbonate urethane(PCU)nano-fibers were fabricated via electrospinning using N,Ndimethylformamide(DMF)and tetrahydrofuran(THF)as the mixed solvent.The effect of volume ratios of DMF and THF in the mixed solvent on the fiber structures was investigated.The results show that nano-fibers with a narrow diameter distribution and a few defects were obtained when mixed solvent with the appropriate volume ratio of DMF and THF as 1∶1.When the proportion of DMF was more than 75%in the mixed solvent,it was easy to form many beaded fibers.The applied voltage in the electrospinning process has a significant influence on the morphology of fibers.When the electric voltage was set between 22 and 32 kV,the average diameters of the fibers were found between 420 and 570 nm.Scanning electron microscopy(SEM)images showed that fiber diameter and structural morphology of the electrospun PCU membranes are a function of the polymer solution concentration.When the concentration of PCU solution was 6.0 wt-%,a beaded-fiber microstructure was obtained.With increasing the concentration of PCU solutions above 6.0 wt-%,beaded fiber decreased and finally disappeared.However,when the PCU concentration was over 14.0 wt-%,the average diameter of fibers became large,closed to 2μm,because of the high solution viscosity.The average diameter of nanofibers increased linearly with increasing the volume flow rate of the PCU solution(10.0 wt-%)when the applied voltagewas 24 kV.The results show that the morphology of PCU fibers could be controlled by electrospinning parameters,such as solution concentration,electric voltage and flow rate.
基金supported by the National Natural Science Foundation of China(Grant No.52073204)。
文摘Mismatched biomechanical properties between artificial vascular grafts and native blood vessels can result in intimal hyperplasia,especially for the implantation of small-diameter blood vessels.Ideal biomaterials for vascular repair still remain challenged.Biodegradable poly(ε-caprolactone)(PCL)has been applied for the preparation of electrospun vascular grafts,but more efforts are needed to improve its compliance with tissue growth.Herein,L-arginine-based poly(ester urethane)urea(PEUU)with both elasticity and biodegradability was synthesized so as to enhance the biomechanical properties of vascular grafts by blending electrospinning with PCL in a given mass ratio.It was exhibited that the prepared electrospun PCL/PEUU fibrous membranes were suitable for cell proliferation with normal cell morphology.More importantly,the electrospun membrane with 1/1 mass ratio of PCL/PEUU(PEUU50)showed specific flexibility,exhibiting more suitable mechanical properties matching to the native blood vessels.Specifically,the PEUU50 electrospun membrane demonstrated significantly lower Young’s modulus(9.3±0.8 MPa)and tensile strength(6.0±0.5 MPa),and extremely higher elongation(389%±24%)in wet state than those(16.3±3.0 MPa,11.4±7.1 MPa and 196%±57%,respectively)of the pristine PCL membrane.Overall,this study demonstrated the great potential of amino acid-based PEUUs for the application in small-diameter vascular grafts.
基金financially supported by the National Key Research and Development Program of China(2016YFC1100402)the International Cooperation Project by Science and Technology Department of Sichuan Province(2020YFH0103)+1 种基金the National Natural Science Foundation of China(NSFC Project 81801853),Postdoctoral Science Foundation of China(2018M633400)Sichuan Science and Technology Program(19GJHZ0058).
文摘Polyurethanes are widely used in interventional devices due to the excellent physicochemical property.However,non-specific adhesion and severe inflammatory response of ordinary polyurethanes may lead to severe complications of intravenous devices.Herein,a novel phospholipid-based polycarbonate urethanes(PCUs)were developed via two-step solution polymerization by direct synthesis based on functional raw materials.Furthermore,PCUs were coated on biomedical metal sheets to construct biomimetic anti-fouling surface.The results of stress–strain curves exhibited excellent tensile properties of PCUs films.Differential scanning calorimetry results indicated that the microphase separation of such PCUs polymers could be well regulated by adjusting the formulation of chain extender,leading to different biological response.In vitro blood compatibility tests including bovine serum albumin adsorption,fibrinogen adsorption and denaturation,platelet adhesion and whole-blood experiment showed superior performance in inhibition non-specific adhesion of PCUs samples.Endothelial cells and smooth muscle cells culture tests further revealed a good anti-cell adhesion ability.Finally,animal experiments including ex vivo blood circulation and subcutaneous inflammation animal experiments indicated a strong ability in anti-thrombosis and histocompatibility.These results high light the strong anti-adhesion property of phospholipid-based PCUs films,which may be applied to the blood-contacting implants such as intravenous catheter or antithrombotic surface in the future.