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
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...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 import...展开更多
Herein,we developed a tertiary amine-catalyzed stereoretentive multi-component cascade reaction featuring an amidation/[4+1]annulation/decarboxylation/Curtius rearrangement/[2+n]annulation sequence.This metal-free and...Herein,we developed a tertiary amine-catalyzed stereoretentive multi-component cascade reaction featuring an amidation/[4+1]annulation/decarboxylation/Curtius rearrangement/[2+n]annulation sequence.This metal-free and step-economic method provided a broad range of cyclic ureas/urethanes in green solvent under mild conditions without employing explosive and toxic reagents.Importantly,this reaction generated isocyanates in situ under catalytic conditions via a decarboxylation/Curtius rearrangement process of dioxazolones.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
Previous studies have shown that visual cortical neurons in old mammals exhibit higher spontaneous activity,higher responsiveness to visual stimuli,and lower selectivity for stimulus orientations and motion directions...Previous studies have shown that visual cortical neurons in old mammals exhibit higher spontaneous activity,higher responsiveness to visual stimuli,and lower selectivity for stimulus orientations and motion directions than did neurons in young adult counterparts.However,whether the responsive difference in cortical neurons between young and old animals resulted from different effects induced by anesthetics has remained unclear.To clarify this issue,we recorded the response properties of individual neurons in the primary visual cortex of old and young adult cats while systematically varying the anesthesia level of urethane,a widely used anesthetic in physiology experiments.Our results showed that cumulatively administrating 50 mg and 100 mg of urethane upon the minimal level of urethane required to anesthetize an old or young adult cat did not significantly alter the degree of neuronal response selectivity for stimulus orientations and motion directions nor significantly change the visually-driven response and spontaneous activity of neurons in old and young adult cats.Cumulatively administrating 150 mg of urethane decreased neuronal responsiveness similarly in both age groups.Therefore,urethane appears to exert similar effects on neuronal response properties of old and young adult animals.展开更多
UV-curable hyperbranched polyurethane acrylate-polyurethane diacrylate/SiO2 dispersion （HBPUA-PUDA/SiO2） was prepared with isophorone diisocyanate （IPDI）, hyperbranched polyester Boltorn H20 （H20）, hydroxy-ethyl...UV-curable hyperbranched polyurethane acrylate-polyurethane diacrylate/SiO2 dispersion （HBPUA-PUDA/SiO2） was prepared with isophorone diisocyanate （IPDI）, hyperbranched polyester Boltorn H20 （H20）, hydroxy-ethyl acrylate （HEA）, polyethyleneglycol （PEG-200）and nano-SiO2. The UV curing kinetics of the films was investigated by FTIR. The results show that the curing speed of the films increases with the adding of nano-SiO2 and decreases with the adding of PUDA due to the slower chain movement. The thermal stability of the HBPUA-PUDA/SiO2 films was studied by using thermogravimetric analysis coupled with Fourier transform infrared spectroscopy （TGA/FTIR）. The results show that all films exhibit two degradation stages located at about 320 and 440℃ corresponding to the degradation for hard segments of urethane-acrylate and the degradation for soft segment and polyester core. In addition, the results from the analysis of TGA/FTIR also indicate that the decomposition temperature of HBPUA-PUDA/SiO2 film is 15℃ higher than that obtained for pure polymer. The degradation mechanism was proposed according to TGA/FTIR results.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
Two kinds of water-soluble and ultraviolet (UV) curable oligomers were synthesized and characterized. The oligomers were evaluated as resins for water-based UV curable coating. The rheology of the two oligomers' a...Two kinds of water-soluble and ultraviolet (UV) curable oligomers were synthesized and characterized. The oligomers were evaluated as resins for water-based UV curable coating. The rheology of the two oligomers' aqueous so-lutions was investigated in terms of solid fraction, pH dependence, and temperature dependence. The solutions were found to be Newtonian fluid showing rather low viscosity even at high solid fraction of 0.55. The drying process of the coatings and the properties of the cured coatings were studied by comparing them with water-dispersed UV-curable polyurethane methyl acrylate. It was evident that the water-soluble coating dried more slowly; and that the overall properties were inferior to those of the water-dispersed coating.展开更多
Metal-free catalysts are preferred during these days in organic synthesis or in polymeriza- tions. Sulfonic acid is reported to be efficient in catalyzing reactions between isocyanates and alcohols. In this work, synt...Metal-free catalysts are preferred during these days in organic synthesis or in polymeriza- tions. Sulfonic acid is reported to be efficient in catalyzing reactions between isocyanates and alcohols. In this work, synthesis of sulfonic acid immobilized organic nanoparticles （nanoacid） and its application in catalyzing urethane formation, are elaborated. The nanoacid can be simply prepared by miniemulsion polymerization with a reactive surfacrant, namely sodium 4-（（perfluoronon-8-en-l-yl）oxy）benzenesulfonate, followed by an acidification. From the images of scanning electron microscope, the nanoacid obtained is found to be narrowly dispersed and the average diameter is around 90 nm. The measured sulfur content is 0.5%, from which the content of sulfonic acid in the nanoparticles is calculated to be 0.16 mmol/g. When catalyzing urethane formation based on hexamethylene diisocyanate and n-butanol, the nanoacid catalyst exhibits considerable efficiency.展开更多
The rapid quantitatively analysis method for IPDI residue in the urethane reaction was studied by LC-ESI+MS using select ion mode(SIM).The results exhibited that the linearity and repeatability of method and recovies ...The rapid quantitatively analysis method for IPDI residue in the urethane reaction was studied by LC-ESI+MS using select ion mode(SIM).The results exhibited that the linearity and repeatability of method and recovies of IPDI met with the requirement.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
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
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
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
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
Surface-modified poly(butadiene)urethane (PBTU) films with silk fibroin (SF) were prepared by simple chemical method under the normal temperature. The physical properties and biological behaviour of the SF-modified PB...Surface-modified poly(butadiene)urethane (PBTU) films with silk fibroin (SF) were prepared by simple chemical method under the normal temperature. The physical properties and biological behaviour of the SF-modified PBTU film were evaluated. The results showed that the SF-modified PBTU films kept the tenacity and pliability very well, and could overcome rigid and brittle weaks of silk fibroin films. The morphology of SF in the PBTU film was dendritic aggregations, and the water-contact angle measurement indicated that the surface hydrophilicity of modified films was apparently enhanced. The biocompatibility of PBTU films was improved due to the change of surface components. The degree of platelet adhesion and the cell viability of rat embryo dermal fibroblasts seeded on PBTU films, SF films, and SF-modified PBTU films were measured by counting platelets before and after they contacted the films and MTT assay, respectively. The results indicated that platelet adhesion resistance and cell viability on the modified film were greatly superior to those on the PBTU film and the compound interface had good stability in the air.展开更多
A series of non-isocyanate linear high molecular weight poly(ester urethane)s(PETUs)were prepared through an environmentallyfriendly route based on dimethyl carbonate,1,6-hexanediol and 1,6-hexanediamine.In this route...A series of non-isocyanate linear high molecular weight poly(ester urethane)s(PETUs)were prepared through an environmentallyfriendly route based on dimethyl carbonate,1,6-hexanediol and 1,6-hexanediamine.In this route,the polyurethane diol was first prepared by the reaction between bis-1,6-hexamethylencarbamate(BHC)and 1,6-hexanediol.A series of polyester soft segments of polyurethane have been synthesized from the polycondensation of adipic acid and different diols,including butanediol,hexanediol,octanediol and decanediol.The subsequent polycondensation of polyurethane diol and polyester diol led to linear PETUs.The resultant polymers were characterized by GPC,FTIR,^(1)H-NMR,^(13)C-NMR,DSC,WAXD,TGA and tensile test.The results indicated that PETUs possess weight-average molecular weights higher than 1×10^(5) and the tensile strength as high as 10 MPa.The thermal properties,crystallization behavior,microphase separation behavior and morphology were studied by DSC and AFM,and the results indicated that the degree of phase separation was affected by two factors,the crystallization and hydrogen bonding interaction between soft segment and hard segment.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
Heparin was grafted onto polycarbonate urethane (PCU) surface via a three-step procedure utilizing α, ωdiamino-poly(ethylene glycol) (APEG, M n =2 000) as a spacer. In the first step, isocyanate functional groups we...Heparin was grafted onto polycarbonate urethane (PCU) surface via a three-step procedure utilizing α, ωdiamino-poly(ethylene glycol) (APEG, M n =2 000) as a spacer. In the first step, isocyanate functional groups were introduced onto PCU surface by the treatment of hexamethylene diisocyanate (HDI) in the presence of di-n-butyltin dilaurate (DBTDL) as a catalyst. In the second step, APEG was linked to the PCU surface to obtain the APEG conjugated PCU surface (PCU-APEG). In the third step, heparin was covalently coupled with PCU-APEG in the presence of N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylamidopropyl) carbodiimide (EDAC). The amount of heparin (1.639 μg/cm 2 ) covalently immobilized on the PCU-APEG surface was determined by the toluidine blue method. The modified surface was characterized by water contact angle, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The hemocompatibility was preliminarily studied by platelet adhesion test. The results indicated that heparin was successfully grafted onto the PCU surface, and meanwhile the hydrophilicity and hemocompatibility of the modified PCU surface were improved significantly compared with the blank PCU surface.展开更多
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 import...
基金financial support provided by the National Natural Science Foundation of China(22207063)111 Project(D20015),Hubei Provincial Central Government Guided Local Science and Technology Development Project(2024BSB016)+1 种基金Natural Science Research Project of Yichang City(A23-2-002)the Opening Funding of Hubei Key Laboratory of Natural Products Research and Development,China Three Gorges University(2024NPRD03,2024NPRD04,2024NPRD05).
文摘Herein,we developed a tertiary amine-catalyzed stereoretentive multi-component cascade reaction featuring an amidation/[4+1]annulation/decarboxylation/Curtius rearrangement/[2+n]annulation sequence.This metal-free and step-economic method provided a broad range of cyclic ureas/urethanes in green solvent under mild conditions without employing explosive and toxic reagents.Importantly,this reaction generated isocyanates in situ under catalytic conditions via a decarboxylation/Curtius rearrangement process of dioxazolones.
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.
基金Supported by Natural Science Foundation of Anhui Province (070413138)the Key Research Foundation of Anhui Province Education Department (KJ2009A167)
文摘Previous studies have shown that visual cortical neurons in old mammals exhibit higher spontaneous activity,higher responsiveness to visual stimuli,and lower selectivity for stimulus orientations and motion directions than did neurons in young adult counterparts.However,whether the responsive difference in cortical neurons between young and old animals resulted from different effects induced by anesthetics has remained unclear.To clarify this issue,we recorded the response properties of individual neurons in the primary visual cortex of old and young adult cats while systematically varying the anesthesia level of urethane,a widely used anesthetic in physiology experiments.Our results showed that cumulatively administrating 50 mg and 100 mg of urethane upon the minimal level of urethane required to anesthetize an old or young adult cat did not significantly alter the degree of neuronal response selectivity for stimulus orientations and motion directions nor significantly change the visually-driven response and spontaneous activity of neurons in old and young adult cats.Cumulatively administrating 150 mg of urethane decreased neuronal responsiveness similarly in both age groups.Therefore,urethane appears to exert similar effects on neuronal response properties of old and young adult animals.
文摘UV-curable hyperbranched polyurethane acrylate-polyurethane diacrylate/SiO2 dispersion （HBPUA-PUDA/SiO2） was prepared with isophorone diisocyanate （IPDI）, hyperbranched polyester Boltorn H20 （H20）, hydroxy-ethyl acrylate （HEA）, polyethyleneglycol （PEG-200）and nano-SiO2. The UV curing kinetics of the films was investigated by FTIR. The results show that the curing speed of the films increases with the adding of nano-SiO2 and decreases with the adding of PUDA due to the slower chain movement. The thermal stability of the HBPUA-PUDA/SiO2 films was studied by using thermogravimetric analysis coupled with Fourier transform infrared spectroscopy （TGA/FTIR）. The results show that all films exhibit two degradation stages located at about 320 and 440℃ corresponding to the degradation for hard segments of urethane-acrylate and the degradation for soft segment and polyester core. In addition, the results from the analysis of TGA/FTIR also indicate that the decomposition temperature of HBPUA-PUDA/SiO2 film is 15℃ higher than that obtained for pure polymer. The degradation mechanism was proposed according to TGA/FTIR results.
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Two kinds of water-soluble and ultraviolet (UV) curable oligomers were synthesized and characterized. The oligomers were evaluated as resins for water-based UV curable coating. The rheology of the two oligomers' aqueous so-lutions was investigated in terms of solid fraction, pH dependence, and temperature dependence. The solutions were found to be Newtonian fluid showing rather low viscosity even at high solid fraction of 0.55. The drying process of the coatings and the properties of the cured coatings were studied by comparing them with water-dispersed UV-curable polyurethane methyl acrylate. It was evident that the water-soluble coating dried more slowly; and that the overall properties were inferior to those of the water-dispersed coating.
文摘Metal-free catalysts are preferred during these days in organic synthesis or in polymeriza- tions. Sulfonic acid is reported to be efficient in catalyzing reactions between isocyanates and alcohols. In this work, synthesis of sulfonic acid immobilized organic nanoparticles （nanoacid） and its application in catalyzing urethane formation, are elaborated. The nanoacid can be simply prepared by miniemulsion polymerization with a reactive surfacrant, namely sodium 4-（（perfluoronon-8-en-l-yl）oxy）benzenesulfonate, followed by an acidification. From the images of scanning electron microscope, the nanoacid obtained is found to be narrowly dispersed and the average diameter is around 90 nm. The measured sulfur content is 0.5%, from which the content of sulfonic acid in the nanoparticles is calculated to be 0.16 mmol/g. When catalyzing urethane formation based on hexamethylene diisocyanate and n-butanol, the nanoacid catalyst exhibits considerable efficiency.
文摘The rapid quantitatively analysis method for IPDI residue in the urethane reaction was studied by LC-ESI+MS using select ion mode(SIM).The results exhibited that the linearity and repeatability of method and recovies of IPDI met with the requirement.
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%.
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.
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.
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Major State Basic Research Development Programof China (No.2005CB623906)
文摘Surface-modified poly(butadiene)urethane (PBTU) films with silk fibroin (SF) were prepared by simple chemical method under the normal temperature. The physical properties and biological behaviour of the SF-modified PBTU film were evaluated. The results showed that the SF-modified PBTU films kept the tenacity and pliability very well, and could overcome rigid and brittle weaks of silk fibroin films. The morphology of SF in the PBTU film was dendritic aggregations, and the water-contact angle measurement indicated that the surface hydrophilicity of modified films was apparently enhanced. The biocompatibility of PBTU films was improved due to the change of surface components. The degree of platelet adhesion and the cell viability of rat embryo dermal fibroblasts seeded on PBTU films, SF films, and SF-modified PBTU films were measured by counting platelets before and after they contacted the films and MTT assay, respectively. The results indicated that platelet adhesion resistance and cell viability on the modified film were greatly superior to those on the PBTU film and the compound interface had good stability in the air.
基金the National Natural Science Foundation of China(Nos.52173009,81971711,21574137,51373186)Beijing Natural Science Foundation(No.2192065)National Key R&D Program of China(No.2016YFB1100800)。
文摘A series of non-isocyanate linear high molecular weight poly(ester urethane)s(PETUs)were prepared through an environmentallyfriendly route based on dimethyl carbonate,1,6-hexanediol and 1,6-hexanediamine.In this route,the polyurethane diol was first prepared by the reaction between bis-1,6-hexamethylencarbamate(BHC)and 1,6-hexanediol.A series of polyester soft segments of polyurethane have been synthesized from the polycondensation of adipic acid and different diols,including butanediol,hexanediol,octanediol and decanediol.The subsequent polycondensation of polyurethane diol and polyester diol led to linear PETUs.The resultant polymers were characterized by GPC,FTIR,^(1)H-NMR,^(13)C-NMR,DSC,WAXD,TGA and tensile test.The results indicated that PETUs possess weight-average molecular weights higher than 1×10^(5) and the tensile strength as high as 10 MPa.The thermal properties,crystallization behavior,microphase separation behavior and morphology were studied by DSC and AFM,and the results indicated that the degree of phase separation was affected by two factors,the crystallization and hydrogen bonding interaction between soft segment and hard segment.
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.
基金Supported by International Cooperation from Ministry of Science and Technology of China(No.2008DFA51170)Science and Technology Project of Tianjin Municipal Science and Technology Commission(No.08ZCKFSF03300)
文摘Heparin was grafted onto polycarbonate urethane (PCU) surface via a three-step procedure utilizing α, ωdiamino-poly(ethylene glycol) (APEG, M n =2 000) as a spacer. In the first step, isocyanate functional groups were introduced onto PCU surface by the treatment of hexamethylene diisocyanate (HDI) in the presence of di-n-butyltin dilaurate (DBTDL) as a catalyst. In the second step, APEG was linked to the PCU surface to obtain the APEG conjugated PCU surface (PCU-APEG). In the third step, heparin was covalently coupled with PCU-APEG in the presence of N-hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylamidopropyl) carbodiimide (EDAC). The amount of heparin (1.639 μg/cm 2 ) covalently immobilized on the PCU-APEG surface was determined by the toluidine blue method. The modified surface was characterized by water contact angle, attenuated total reflection Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and atomic force microscopy (AFM). The hemocompatibility was preliminarily studied by platelet adhesion test. The results indicated that heparin was successfully grafted onto the PCU surface, and meanwhile the hydrophilicity and hemocompatibility of the modified PCU surface were improved significantly compared with the blank PCU surface.
