Incorporation of acetal groups in the backbone is a potent strategy to create polymers that are cleavable or degradable under acidic conditions.We report here an in-depth study on the ring-closing-opening copolymeriza...Incorporation of acetal groups in the backbone is a potent strategy to create polymers that are cleavable or degradable under acidic conditions.We report here an in-depth study on the ring-closing-opening copolymerization of o-phthalaldehyde(OPA)and epoxide using Lewis pair type two-component organocatalysts for producing acetal-functionalized polyether and polyurethane.Notably,triethylborane as the Lewis acid,in comparison with tri(n-butyl)borane,more effectively enhances the polymerization activity by mitigating borane-induced reduction of the aldehyde group into extra initiating(borinic ester)species.Density functional theory(DFT)calculations present comparable energy barriers of OPA-epoxide cross-propagation and epoxide self-propagation,which is consistent with the experimental finding that an alternating-rich copolymer comprising mostly OPA-epoxide units but also epoxide-epoxide linkages is produced.In particular,when epoxide is added in a large excess,the product becomes a polyether containing acetal functionalities in the central part of the backbone and thus being convertible into polyurethane with refined acid degradability.展开更多
Three new catalysts based on the silica gel supported polyether ionic liquids(ILs), i.e., [HO-PECH-MIM]ClSi, [H2N-PECH-MIM]Cl-Si, and [HOOC-PECH-MIM]Cl-Si, were prepared, and their chemical structures were characteriz...Three new catalysts based on the silica gel supported polyether ionic liquids(ILs), i.e., [HO-PECH-MIM]ClSi, [H2N-PECH-MIM]Cl-Si, and [HOOC-PECH-MIM]Cl-Si, were prepared, and their chemical structures were characterized by infrared(IR) spectroscopy and nuclear magnetic resonance(NMR) spectroscopy. Thermogravimetric analyzer(TG), X-ray diffractometer(XRD) and scanning electron microscope(SEM) were used to evaluate their thermal stability,crystalline structure and apparent morphology, respectively. Surface areas of the prepared catalysts were calculated by the Brunauer-Emmett-Teller(BET) method. The catalytic reaction for the synthesis of propylene carbonate(PC) using CO_2 and propylene oxide(PO) in the presence of the prepared catalysts was studied. The influences of times of recycling and catalyst structure on catalytic performance were also investigated. The experimental results showed that the silica gel supported polyether ILs catalysts successfully prepared under mild condition could possess the advantages of high activity, excellent thermal stability, good selectivity and easy recycling, while the phase transition of the liquid polyether ILs catalysts was also achieved. When the reaction temperature was 90 °C, the CO_2 pressure was 2.0 MPa and the dosage of the catalyst was 2.5%, [HOOC-PECH-MIM]Cl-Si was found to have the best catalytic performance in the catalytic process, with the conversion rate reaching 100% and the selectivity equating to 98.2%. The conversion rate and selectivity still could reach more than 90% even after the catalyst was reused for 15 times.展开更多
The composition and sequence distribution of monomeric units in polyester polyether multiblock copolymer were studied by pyrolysis? gas chromatography (PGC) and pyrolysis gas chromatography/mass spectrometry (PGC/M...The composition and sequence distribution of monomeric units in polyester polyether multiblock copolymer were studied by pyrolysis? gas chromatography (PGC) and pyrolysis gas chromatography/mass spectrometry (PGC/MS). PGC was applied to study the F t curve of the multiblock copolymer and PGC/MS was used to separate and identify the pyrolyzates. DTA experiment was used to study the decomposition temperature. The results show that the beginning point of elastomer’s decomposition was about 300?℃ and the decomposition temperature of most of the sample was 550?℃. Many pyrolyzates were produced because of the breaking of weak bonds in the sample. The possible microstructure was verified and the pyrolysis pathway of the copolymer was investigated.展开更多
A high performance thermosetting epoxy resin crosslinkable at room temperature was obtained via directly moulding diglycidyl ether of bisphenol A（DGEBA） and flexibleα,ω-bisamino（n-alkylene）phenyl terminated poly...A high performance thermosetting epoxy resin crosslinkable at room temperature was obtained via directly moulding diglycidyl ether of bisphenol A（DGEBA） and flexibleα,ω-bisamino（n-alkylene）phenyl terminated poly（ethylene glycol）.The influences of the n-alkylene inserted in aminophenyl of flexible amino-terminated polythers（ATPE） on the mechanical properties,fractographs and curing kinetics of the ATPE-DGEBA cured products were studied.The results show that the insertion of n-alkylene group into the aminophenyl group of the ATPE,on one hand,can significantly increase the strain relaxation rate and decrease glass transition temperature of the ATPE-DGEBA cured products,resulting in slight decrease of the Young’s modulus and tensile strength,and significant increase of the toughness and elongation of the ATPE-DGEBA cured products.On the other hand,it can remarkably enhance the reactivity of amine with epoxy,much accelerating the curing rate of the ATPE-DGEBA systems.The activation energy of DGEBA cured by BAPTPE,BAMPTPE and BAEPTPE was 53.1,28.5 and 25.4 kJ·mol;,respectively.The as-obtained ATPE-DGEBA cured products are homogeneous, transparent,and show excellent mechanical properties including tensile strength and toughness.Thus they are promising to have important applications in structure adhesives,casting bulk materials,functional coatings,cryogenic engineering, damping and sound absorbing materials.展开更多
A novel liquid hyperbranched polyether epoxy （HBPEE） based on commercially available hydroquinone （HQ） and 1,1,1-trihydroxymethylpropane triglycidyl ether （TMPGE） was synthesized through an A2 ＋ B3 one-step pro...A novel liquid hyperbranched polyether epoxy （HBPEE） based on commercially available hydroquinone （HQ） and 1,1,1-trihydroxymethylpropane triglycidyl ether （TMPGE） was synthesized through an A2 ＋ B3 one-step proton transfer polymerization. In order to improve the toughness, the synthesized HBPEE was mixed with diglycidyl ether of bisphenol A （DGEBA） in different ratios to form hybrids and cured with triethylenetetramine （TETA）. Thermal and mechanical properties of the cured hybrids were evaluated. Results show that addition of HBPEE can improve the toughness of cured hybrids remarkably at 〈 20 wt% loading, without compromising the tensile strength. However, the glass transition temperature （Tg） of the cured hybrids decreases with increasing HBPEE content. Fracture surface images from scanning electron microscope show oriented fibrils in hybrids containing HBPEE. The formation and orientation of the fibrils can absorb energy under impact and lead to an improvement of toughness. Furthermore, based on the morphology of fractured surfaces and the single Tg in each hybrid, no sign of phase separation was found in the cured hybrid systems. As a result, the toughening mechanism could be explained by in situ homogeneous toughening mechanism rather than phase separation mechanism.展开更多
[Objectives] This study was conducted to establish an LC-MS/MS method for the determination of three kinds of polyether residues in eggs with QuEChERS dSPE EMR-Lipid as a pretreatment method, which was established acc...[Objectives] This study was conducted to establish an LC-MS/MS method for the determination of three kinds of polyether residues in eggs with QuEChERS dSPE EMR-Lipid as a pretreatment method, which was established according to Agilent Bond Elut enhanced lipid removal EMR-Lipid technology. [ Methods] Egg was extracted by acidified acetonitrile, purified by Bond Elut EMR-Lipid QuEChERS, and detected by HPLC-MS/MS. [ Results] The three kinds of polyether residues had good linear relationships in the range of 2.0 - 100 μg/L with peak areas, r 〉 0. 999. The recoveries ranged from 84.6% to 107.0%. [ Conclusions ] The method is convenient and accurate, and the quantitative results are accurate and reproducible. It is suitable for the determination of the three kinds of polyether residues in eggs.展开更多
Catalytic hydrogenation of SBS was performed for the first time in polyether molten salt with Ru/TPPTS complex as catalyst. Experimental results showed that the hydrogenation degree can be enhanced significantly by th...Catalytic hydrogenation of SBS was performed for the first time in polyether molten salt with Ru/TPPTS complex as catalyst. Experimental results showed that the hydrogenation degree can be enhanced significantly by the addition of triphenylphosphine (TPP). When the molar ratio of TPP, TPPTS and Ru is 2:5:1, 89% hydrogenation degree can be achieved after 12 h under reaction conditions of 5.0 MPa and 150°C. The ionic liquid containing catalyst can be reused three times without obvious changes in the catalytic selectivity and activity.展开更多
Over the last half-century,polyether ether ketone(PEEK)has emerged as a widely adopted thermoplastic polymer,primarily due to its lower density,exceptional mechanical properties,high-temperature and chemical resistanc...Over the last half-century,polyether ether ketone(PEEK)has emerged as a widely adopted thermoplastic polymer,primarily due to its lower density,exceptional mechanical properties,high-temperature and chemical resistance,and biocompatibility.PEEK and its composites have found extensive applications across various fields,including machinery,aerospace,military equipment,electronics,and biomedicine,positioning themselves as promising substitutes for traditional metal structures.Nevertheless,achieving optimal performance and functional molding of PEEK and its composites presents a formidable challenge,given their inherent characteristics,such as semi-crystallinity,high melting temperature,heightened viscosity,low dielectric coefficient,and hydrophobic properties.In this paper,we present a comprehensive review of the molding methods and processes of PEEK and its composites,including extrusion molding,hot compression molding,injection molding,and 3D printing.We also introduce typical innovative applications within the fields of mechanics,electricity,and biomedicine while elucidating methodologies that leverage the distinctive advantages of PEEK and its composites.Additionally,we summarize research findings related to manipulating the properties of PEEK and its composites through the optimization of machine parameters,process variables,and material structural adjustments.Finally,we contemplate the prevailing development trends and outline prospective avenues for further research in the advancement and molding of PEEK and its composites.展开更多
Fluorinated polyether dendritic sectors 4, 7 and 10 from the first to the third generations, respectively, were prepared by a convergent approach from readily available pentafluorophenol, phloroglucinol and 1,3-dibrom...Fluorinated polyether dendritic sectors 4, 7 and 10 from the first to the third generations, respectively, were prepared by a convergent approach from readily available pentafluorophenol, phloroglucinol and 1,3-dibromopropane. These dendritic sectors have good solubility properties and are stable in both acidic and basic media. Hence they are useful dendritic building blocks for the preparation of functional dendrimers.展开更多
Nitrate ester plasticized polyether(NEPE)is a kind of high-energy solid propellant that has both good mechanical properties and high specific impulse.However,its unique composition makes its combustion mechanism diffe...Nitrate ester plasticized polyether(NEPE)is a kind of high-energy solid propellant that has both good mechanical properties and high specific impulse.However,its unique composition makes its combustion mechanism different from both double-base propellants and composite propellants.In order to study the combustion mechanism of NEPE propellants,we improved the free radical cracking model of previous research to make it capable of predicting the burning rate of NEPE propellants.To study the combustion characteristics and provide data support for the model,an experimental system was built and four kinds of NEPE propellants with different compositions and grain size distributions were tested.The results show that our modified model can reflect the combustion characteristics of NEPE propellants with an acceptable accuracy.The difference between the model and the experimental data is mainly caused by uncertain environmental factors and the ignorance of interactions between components.Both the experimental data and the results predicted by the model show that increasing the backpressure helps to increase the burning rate of NEPE propellants.Furthermore,the grain size of the oxidizer inside the NEPE propellant has a more severe impact on the burning rate but a lighter impact on the burning rate pressure exponent in comparison with the grain size of aluminum.For aluminum-free NEPE propellants,the reaction in the gas phase is dominant in the combustion process while adding aluminum into the propellant makes the solid phase dominant in the final stage.The combustion of fine aluminum particles near the burning surface generates heat feedback to the burning surface which evidently influences the surface temperature.However,the agglomeration of coarse aluminum particles has little effect on the burning surface temperature.展开更多
Proton conducting composite membranes from sulfonated polyether ether ketone and SiO2 for direct methanol fuel cell （DMFC） application were prepared with sulfonated polyether ether ketone（SPEEK） and tetracethoxy s...Proton conducting composite membranes from sulfonated polyether ether ketone and SiO2 for direct methanol fuel cell （DMFC） application were prepared with sulfonated polyether ether ketone（SPEEK） and tetracethoxy silane（TEOS） by sol-gel method. The covalent crosslinking structure was formed between —SO3H of SPEEK via SiO2. The SEM images show that the interfacial compatibility of SPEEK and SiO2 is improved obviously and SiO2 disperses uniformly in the polymer matrix and the particle diameter of SiO2 does not exceed 40 nm. The proton conductivity of composite membranes decreases slightly compared with the SPEEK membrane while the methanol permeability and swelling of composite membrane are improved remarkablely owing to covalent cross-linking between —SO3H and SiO2 .展开更多
基金financially supported by the National Key R&D Program of China(No.2022YFC2805103)the National Natural Science Foundation of China(Nos.52022031 and 52263001)the Foundation from Qinghai Science and Technology Department(No.2022-ZJ-944Q)。
文摘Incorporation of acetal groups in the backbone is a potent strategy to create polymers that are cleavable or degradable under acidic conditions.We report here an in-depth study on the ring-closing-opening copolymerization of o-phthalaldehyde(OPA)and epoxide using Lewis pair type two-component organocatalysts for producing acetal-functionalized polyether and polyurethane.Notably,triethylborane as the Lewis acid,in comparison with tri(n-butyl)borane,more effectively enhances the polymerization activity by mitigating borane-induced reduction of the aldehyde group into extra initiating(borinic ester)species.Density functional theory(DFT)calculations present comparable energy barriers of OPA-epoxide cross-propagation and epoxide self-propagation,which is consistent with the experimental finding that an alternating-rich copolymer comprising mostly OPA-epoxide units but also epoxide-epoxide linkages is produced.In particular,when epoxide is added in a large excess,the product becomes a polyether containing acetal functionalities in the central part of the backbone and thus being convertible into polyurethane with refined acid degradability.
基金supported by the National Natural Science Foundation of China (NSFC 21706163)the Liaoning Province Department of Education Foundation (LQGD2017020)
文摘Three new catalysts based on the silica gel supported polyether ionic liquids(ILs), i.e., [HO-PECH-MIM]ClSi, [H2N-PECH-MIM]Cl-Si, and [HOOC-PECH-MIM]Cl-Si, were prepared, and their chemical structures were characterized by infrared(IR) spectroscopy and nuclear magnetic resonance(NMR) spectroscopy. Thermogravimetric analyzer(TG), X-ray diffractometer(XRD) and scanning electron microscope(SEM) were used to evaluate their thermal stability,crystalline structure and apparent morphology, respectively. Surface areas of the prepared catalysts were calculated by the Brunauer-Emmett-Teller(BET) method. The catalytic reaction for the synthesis of propylene carbonate(PC) using CO_2 and propylene oxide(PO) in the presence of the prepared catalysts was studied. The influences of times of recycling and catalyst structure on catalytic performance were also investigated. The experimental results showed that the silica gel supported polyether ILs catalysts successfully prepared under mild condition could possess the advantages of high activity, excellent thermal stability, good selectivity and easy recycling, while the phase transition of the liquid polyether ILs catalysts was also achieved. When the reaction temperature was 90 °C, the CO_2 pressure was 2.0 MPa and the dosage of the catalyst was 2.5%, [HOOC-PECH-MIM]Cl-Si was found to have the best catalytic performance in the catalytic process, with the conversion rate reaching 100% and the selectivity equating to 98.2%. The conversion rate and selectivity still could reach more than 90% even after the catalyst was reused for 15 times.
文摘The composition and sequence distribution of monomeric units in polyester polyether multiblock copolymer were studied by pyrolysis? gas chromatography (PGC) and pyrolysis gas chromatography/mass spectrometry (PGC/MS). PGC was applied to study the F t curve of the multiblock copolymer and PGC/MS was used to separate and identify the pyrolyzates. DTA experiment was used to study the decomposition temperature. The results show that the beginning point of elastomer’s decomposition was about 300?℃ and the decomposition temperature of most of the sample was 550?℃. Many pyrolyzates were produced because of the breaking of weak bonds in the sample. The possible microstructure was verified and the pyrolysis pathway of the copolymer was investigated.
基金supported by the National 863 Plan(No.2006AA03A209)New Century Excellent Talent Plan (No.NECT-05-0660) from Ministry of EducationDefense Basic Research Item(No.D1420061057)
文摘A high performance thermosetting epoxy resin crosslinkable at room temperature was obtained via directly moulding diglycidyl ether of bisphenol A（DGEBA） and flexibleα,ω-bisamino（n-alkylene）phenyl terminated poly（ethylene glycol）.The influences of the n-alkylene inserted in aminophenyl of flexible amino-terminated polythers（ATPE） on the mechanical properties,fractographs and curing kinetics of the ATPE-DGEBA cured products were studied.The results show that the insertion of n-alkylene group into the aminophenyl group of the ATPE,on one hand,can significantly increase the strain relaxation rate and decrease glass transition temperature of the ATPE-DGEBA cured products,resulting in slight decrease of the Young’s modulus and tensile strength,and significant increase of the toughness and elongation of the ATPE-DGEBA cured products.On the other hand,it can remarkably enhance the reactivity of amine with epoxy,much accelerating the curing rate of the ATPE-DGEBA systems.The activation energy of DGEBA cured by BAPTPE,BAMPTPE and BAEPTPE was 53.1,28.5 and 25.4 kJ·mol;,respectively.The as-obtained ATPE-DGEBA cured products are homogeneous, transparent,and show excellent mechanical properties including tensile strength and toughness.Thus they are promising to have important applications in structure adhesives,casting bulk materials,functional coatings,cryogenic engineering, damping and sound absorbing materials.
基金supported by the Natural Science Foundation of Beijing(No.2092023)National Natural Science Foundation of China(No.51173012)the Fundamental Research Funds for the Central Universities(No.ZZ0912)
文摘A novel liquid hyperbranched polyether epoxy （HBPEE） based on commercially available hydroquinone （HQ） and 1,1,1-trihydroxymethylpropane triglycidyl ether （TMPGE） was synthesized through an A2 ＋ B3 one-step proton transfer polymerization. In order to improve the toughness, the synthesized HBPEE was mixed with diglycidyl ether of bisphenol A （DGEBA） in different ratios to form hybrids and cured with triethylenetetramine （TETA）. Thermal and mechanical properties of the cured hybrids were evaluated. Results show that addition of HBPEE can improve the toughness of cured hybrids remarkably at 〈 20 wt% loading, without compromising the tensile strength. However, the glass transition temperature （Tg） of the cured hybrids decreases with increasing HBPEE content. Fracture surface images from scanning electron microscope show oriented fibrils in hybrids containing HBPEE. The formation and orientation of the fibrils can absorb energy under impact and lead to an improvement of toughness. Furthermore, based on the morphology of fractured surfaces and the single Tg in each hybrid, no sign of phase separation was found in the cured hybrid systems. As a result, the toughening mechanism could be explained by in situ homogeneous toughening mechanism rather than phase separation mechanism.
基金Supported by Science and Technology Planning Project of Huizhou City(20161117141959)
文摘[Objectives] This study was conducted to establish an LC-MS/MS method for the determination of three kinds of polyether residues in eggs with QuEChERS dSPE EMR-Lipid as a pretreatment method, which was established according to Agilent Bond Elut enhanced lipid removal EMR-Lipid technology. [ Methods] Egg was extracted by acidified acetonitrile, purified by Bond Elut EMR-Lipid QuEChERS, and detected by HPLC-MS/MS. [ Results] The three kinds of polyether residues had good linear relationships in the range of 2.0 - 100 μg/L with peak areas, r 〉 0. 999. The recoveries ranged from 84.6% to 107.0%. [ Conclusions ] The method is convenient and accurate, and the quantitative results are accurate and reproducible. It is suitable for the determination of the three kinds of polyether residues in eggs.
基金This work was financially supported by the National Natural Science Foundation of China(NO. 204760l5).
文摘Catalytic hydrogenation of SBS was performed for the first time in polyether molten salt with Ru/TPPTS complex as catalyst. Experimental results showed that the hydrogenation degree can be enhanced significantly by the addition of triphenylphosphine (TPP). When the molar ratio of TPP, TPPTS and Ru is 2:5:1, 89% hydrogenation degree can be achieved after 12 h under reaction conditions of 5.0 MPa and 150°C. The ionic liquid containing catalyst can be reused three times without obvious changes in the catalytic selectivity and activity.
基金supported by the National Key R&D Program of China(No.2022YFC2401903)the“Pioneer”and the“Leading Goose”R&D Program of Zhejiang Province(No.2023C01170)+1 种基金the National Natural Science Foundation of China(No.52205424)the Key Project of Science and Technology Innovation 2025 of Ningbo(No.2023Z029),China.
文摘Over the last half-century,polyether ether ketone(PEEK)has emerged as a widely adopted thermoplastic polymer,primarily due to its lower density,exceptional mechanical properties,high-temperature and chemical resistance,and biocompatibility.PEEK and its composites have found extensive applications across various fields,including machinery,aerospace,military equipment,electronics,and biomedicine,positioning themselves as promising substitutes for traditional metal structures.Nevertheless,achieving optimal performance and functional molding of PEEK and its composites presents a formidable challenge,given their inherent characteristics,such as semi-crystallinity,high melting temperature,heightened viscosity,low dielectric coefficient,and hydrophobic properties.In this paper,we present a comprehensive review of the molding methods and processes of PEEK and its composites,including extrusion molding,hot compression molding,injection molding,and 3D printing.We also introduce typical innovative applications within the fields of mechanics,electricity,and biomedicine while elucidating methodologies that leverage the distinctive advantages of PEEK and its composites.Additionally,we summarize research findings related to manipulating the properties of PEEK and its composites through the optimization of machine parameters,process variables,and material structural adjustments.Finally,we contemplate the prevailing development trends and outline prospective avenues for further research in the advancement and molding of PEEK and its composites.
文摘Fluorinated polyether dendritic sectors 4, 7 and 10 from the first to the third generations, respectively, were prepared by a convergent approach from readily available pentafluorophenol, phloroglucinol and 1,3-dibromopropane. These dendritic sectors have good solubility properties and are stable in both acidic and basic media. Hence they are useful dendritic building blocks for the preparation of functional dendrimers.
基金Project supported by the National Natural Science Foundation of China(No.11572349)the Natural Science Foundation of Hunan Province(No.2018JJ3606),China。
文摘Nitrate ester plasticized polyether(NEPE)is a kind of high-energy solid propellant that has both good mechanical properties and high specific impulse.However,its unique composition makes its combustion mechanism different from both double-base propellants and composite propellants.In order to study the combustion mechanism of NEPE propellants,we improved the free radical cracking model of previous research to make it capable of predicting the burning rate of NEPE propellants.To study the combustion characteristics and provide data support for the model,an experimental system was built and four kinds of NEPE propellants with different compositions and grain size distributions were tested.The results show that our modified model can reflect the combustion characteristics of NEPE propellants with an acceptable accuracy.The difference between the model and the experimental data is mainly caused by uncertain environmental factors and the ignorance of interactions between components.Both the experimental data and the results predicted by the model show that increasing the backpressure helps to increase the burning rate of NEPE propellants.Furthermore,the grain size of the oxidizer inside the NEPE propellant has a more severe impact on the burning rate but a lighter impact on the burning rate pressure exponent in comparison with the grain size of aluminum.For aluminum-free NEPE propellants,the reaction in the gas phase is dominant in the combustion process while adding aluminum into the propellant makes the solid phase dominant in the final stage.The combustion of fine aluminum particles near the burning surface generates heat feedback to the burning surface which evidently influences the surface temperature.However,the agglomeration of coarse aluminum particles has little effect on the burning surface temperature.
文摘Proton conducting composite membranes from sulfonated polyether ether ketone and SiO2 for direct methanol fuel cell （DMFC） application were prepared with sulfonated polyether ether ketone（SPEEK） and tetracethoxy silane（TEOS） by sol-gel method. The covalent crosslinking structure was formed between —SO3H of SPEEK via SiO2. The SEM images show that the interfacial compatibility of SPEEK and SiO2 is improved obviously and SiO2 disperses uniformly in the polymer matrix and the particle diameter of SiO2 does not exceed 40 nm. The proton conductivity of composite membranes decreases slightly compared with the SPEEK membrane while the methanol permeability and swelling of composite membrane are improved remarkablely owing to covalent cross-linking between —SO3H and SiO2 .
