In situ melt polycondensation was proposed to prepare biodegradable aliphatic-aromatic copolyesters/nano-SiO2 hybrids based on terephthalic acid （TPA）, poly（L-lactic acid） oligomer （OLLA）, 1,4-butanediol （BDO）...In situ melt polycondensation was proposed to prepare biodegradable aliphatic-aromatic copolyesters/nano-SiO2 hybrids based on terephthalic acid （TPA）, poly（L-lactic acid） oligomer （OLLA）, 1,4-butanediol （BDO） and nano-SiO2. TEM and FT-IR characterizations confirmed that TPA, OLLA and BDO copolymerized to obtain biodegradable copolyesters, poly（butylene terepbthalate-co-lactate） （PBTL）, and the abundant hydroxyl groups on the surface of nano-SiO2 provided potential sites for in situ grafting with the simultaneous resulted PBTL. The nano-SiO2 particles were chemically wrapped with PBTL to form PBTL/nano- SiO2 hybrids. Due to the good dispersion and interfacial adhesion of nano-SiO2 particles with the copolyester matrix, the tensile strength and the Young＇s modulus increased from 5.4 and 5.6 MPa for neat PBTL to 16 and 390 MPa for PBTL/nano-SiO2 hybrids with 5 wt.% nano-SiO2, respectively. The mechanical properties of PBTL/nano-SiO2 hybrids were substantially improved.展开更多
A series of biodegradable aliphatic-aromatic copolyesters, poly(butylene terephthalate-co-butylene adipate-co- ethylene terephthalate-co-ethylene adipate) (PBATE), were synthesized from terephthalic acid (PTA), adipic...A series of biodegradable aliphatic-aromatic copolyesters, poly(butylene terephthalate-co-butylene adipate-co- ethylene terephthalate-co-ethylene adipate) (PBATE), were synthesized from terephthalic acid (PTA), adipic acid (AA), 1,4-butanediol (BG) and ethylene glycol (EG) through direct esterification and polycondensation. The sequence structure and crystallinity of the copolyester were investigated by 1H NMR spectroscopy and the wide-angle X-ray diffractometry (WAXD). The analytical results showed that the PBATE copolyester was a random copolymer and the composition of PBATE copolyester was almost consistent with the feed molar ratios. The crystal structure of PBATE copolyester belonged to the triclinic crystalline system; The variation in melting point of the synthesized PBATE copolyester agreed well with the estimation obtained by the Flory equation and was applicable to the random copolymer.展开更多
Biodegradable aliphatic/aromatic copolyesters, poly（butylene terephthalate-co-lactate） （PBTL） were prepared via direct melt polycondensation of terephthalic acid （TPA）, 1,4-butanediol （BDO） and poly（L-lactic ...Biodegradable aliphatic/aromatic copolyesters, poly（butylene terephthalate-co-lactate） （PBTL） were prepared via direct melt polycondensation of terephthalic acid （TPA）, 1,4-butanediol （BDO） and poly（L-lactic acid） oligomer （OLLA）. The effects of polymerization time and temperature, as well as aliphatic/aromatic moiety ratio on the physical and thermal properties were investigated. The largest molecular weight of the copolyesters was up to 64100 with molecular weight distribution index of 2.09 when the polycondensation was carried out at 230℃ for 6 h. DSC, XRD, DMA and TGA analysis clearly indicated that the degree of crystallinity, glass-transition temperature, melting point, decomposition temperature, tensile strength, elongation and Young＇s modulus were influenced by the ratio between TPA and OLLA in the final copolyesters. Hydrolytic degradation results demonstrated that the incorporation of biodegradable lactate moieties into the aromatic polyester could efficiently improve hydrolytic degradability of the copolymer even though it still had many aromatic units in the main chains.展开更多
The asymmetric alternating copolymerization of meso-epoxide and cyclic anhydrides provides an efficient access to enantiopure polyesters.Contrary to the extensive investigation of the stereochemistry resulting from ep...The asymmetric alternating copolymerization of meso-epoxide and cyclic anhydrides provides an efficient access to enantiopure polyesters.Contrary to the extensive investigation of the stereochemistry resulting from epoxide building block,the chirality from anhydride and the configurational match with epoxide remain elusive.Herein,we discover that the bimetallic chromium catalysts have led to an obvious enhancement in terms of reactivity and enantioselectivity for the asymmetric copolymerization of meso-epoxide with various non-symmetric chiral anhydrides.Up to 97%ee was obtained during the asymmetric copolymerization of cyclohexene oxide(CHO)with(R)-methylsuccinic anhydride(R-MSA),and three-or four-carbon chiral centers were simultaneously installed in the aliphatic polyester backbone.In particular,the different combinations of stereochemistry in epoxide and anhydride building blocks considerably affect the thermal properties and crystalline behaviors of the resulting polyesters.This study uncovers an interesting method for regulating polymer crystallinity via matching the chirality of different monomers.展开更多
An epoxy-terminated hyperbranched aromatic polyester (P3) was synthesized from a hyperbranched aromatic polyester containing carboxylic acid end groups (P1), which was derived from the condensation polymerization of t...An epoxy-terminated hyperbranched aromatic polyester (P3) was synthesized from a hyperbranched aromatic polyester containing carboxylic acid end groups (P1), which was derived from the condensation polymerization of the AB(2) monomer, 5-acetoxyisophthalic acid. Polymer P1 was converted into the polymeric acid chloride by reaction with thionyl chloride. The acid chloride was reacted with ethanol and glycidol to form a poly(ethyl ester) (P2) and an epoxy terminated material (P3), respectively. The reaction conditions in each step of these processes had to be controlled very carefully to avoid unwanted cross-linking reactions. The characterization of products and intermediates, including molecular weight distributions and thermal properties, are reported.展开更多
The separation of aromatic/aliphatic hydrocarbon mixtures is a significant process in chemical industry, but challenged in some cases. Compared with conventional separation technologies, pervaporation is quite promisi...The separation of aromatic/aliphatic hydrocarbon mixtures is a significant process in chemical industry, but challenged in some cases. Compared with conventional separation technologies, pervaporation is quite promising in terms of its economical, energy-saving, and eco-friendly advantages. However, this technique has not been used in industry for separating aromatic/aliphatic mixtures yet. One of the main reasons is that the separation performance of existed pervaporation membranes is unsatisfactory. Membrane material is an important factor that affects the separation performance. This review provides an overview on the advances in studying membrane materials for the pervaporation separation of aromatic/aliphatic mixtures over the past decade. Explored pristine polymers and their hybrid materials(as hybrid membranes) are summarized to highlight their nature and separation performance. We anticipate that this review could provide some guidance in the development of new materials for the aromatic/aliphatic pervaporation separation.展开更多
The separation of aromatic/aliphatic hydrocarbon mixtures is crucial in the petrochemical industry.Pervaporation is regarded as a promising approach for the separation of aromatic compounds from alkanes. Developing me...The separation of aromatic/aliphatic hydrocarbon mixtures is crucial in the petrochemical industry.Pervaporation is regarded as a promising approach for the separation of aromatic compounds from alkanes. Developing membrane materials with efficient separation performance is still the main task since the membrane should provide chemical stability, high permeation flux, and selectivity. In this study, the hyperbranched polymer(HBP) was deposited on the outer surface of a polyvinylidene fluoride(PVDF)hollow-fiber ultrafiltration membrane by a facile dip-coating method. The dip-coating rate, HBP concentration, and thermal cross-linking temperature were regulated to optimize the membrane structure.The obtained HBP/PVDF hollow-fiber-composite membrane had a good separation performance for aromatic/aliphatic hydrocarbon mixtures. For the 50%/50%(mass) toluene/n-heptane mixture, the permeation flux of optimized composite membranes could reach 1766 g·m^(-2)·h^(-1), with a separation factor of 4.1 at 60℃. Therefore, the HBP/PVDF hollow-fiber-composite membrane has great application prospects in the pervaporation separation of aromatic/aliphatic hydrocarbon mixtures.展开更多
Aliphatic polyesters were synthesized via the ring opening polymerization of the corresponding lactones initiated with dibutylmagnesium both in bulk and in solution. The resulting polymers were characterized by 1H, 13...Aliphatic polyesters were synthesized via the ring opening polymerization of the corresponding lactones initiated with dibutylmagnesium both in bulk and in solution. The resulting polymers were characterized by 1H, 13C NMR, GPC and XRD. The results indicated that dibutylmagnesium is an effective initiator for the ring opening polymerization of lactones.展开更多
The crystalline morphology of a thermotropic aromatic polyester has been studied by microscopy techniques. Spherulites with ringed structure under polarizing micioscope were observed for solution cast specimens, They ...The crystalline morphology of a thermotropic aromatic polyester has been studied by microscopy techniques. Spherulites with ringed structure under polarizing micioscope were observed for solution cast specimens, They were composed of radially growing crystalline lamellae of thickness around 100. It was found that the molecules were packed in the thickness direction. Banded texture was observed in randomly packed domains for melt cast specimens. The bands have the same width and internal structure as those usually observed in oriented specimens of these polymers obtained by shearing their mesomorphic melt.展开更多
Infrared spectra at different temperatures have been studied for fractions ofa liquid crystal tormmg aromatic polyester. The molecular interactions in different phases and their changes duringthe transitions were disc...Infrared spectra at different temperatures have been studied for fractions ofa liquid crystal tormmg aromatic polyester. The molecular interactions in different phases and their changes duringthe transitions were discussed. Abrupt frequency shift was found for bands of groups both in mesogens and flexible spacers during fusion and isotropization transitions. It may imply that both the mesogens and the flexible spacers are included in the same crystalline phase and give their contributions to the formation of the mesophase. The splitting into doublet of the C—O stretching vibrations was observed for both the aromatic and aliphatic esters and was attributed to the existence of local regions for ester groups different in ordering. The more ordered regions do not disappear completely even in the isotropic liquid phase.展开更多
Six new polyesters 7a-f were synthesized through the solution polycondensation reaction of diacid chloride 5 with six aromatic diols 6a-f in N,N-dimethyl acetamide(DMAc) as solvent in the presence of pyridine as base....Six new polyesters 7a-f were synthesized through the solution polycondensation reaction of diacid chloride 5 with six aromatic diols 6a-f in N,N-dimethyl acetamide(DMAc) as solvent in the presence of pyridine as base.The polycondensation reaction produced a series of novel polyester containing pyridyl moiety in the main chain in high yields with inherent viscosities between 0.35 and 0.54 dL/g.The resulted polymers were fully characterized by means of FT-IR spectroscopy,elemental analyses,inherent viscosity ...展开更多
Six aromatic polyesters were prepared for gas separation membranes, and their permeation properties for hydrogen, oxygen, nitrogen, carbon dioxide, and methane were measured at 30 degrees C and 1 atmosphere by low pre...Six aromatic polyesters were prepared for gas separation membranes, and their permeation properties for hydrogen, oxygen, nitrogen, carbon dioxide, and methane were measured at 30 degrees C and 1 atmosphere by low pressure manometric method. The correlation between the gas transport behavior and molecular structure of aromatic polyester membrane is discussed. These data are interpreted qualitatively in terms of the calculated packing density, gas-polymer interaction, concentration of aryl bromine on backbone, and effect of silane group on main chain of polymer.展开更多
Polyesters consisting of substituted aromatic type Schiff base mesogenic unit andpolymethylene spacers were synthesized and their thermal transitions and liquid crystallineproperties were studied. The liquid crystalli...Polyesters consisting of substituted aromatic type Schiff base mesogenic unit andpolymethylene spacers were synthesized and their thermal transitions and liquid crystallineproperties were studied. The liquid crystalline behaviour has been characterized by differentialscanning calorimetry (DSC) and optical polarizing microscopy. Structural broadening bysubstitution of methoxy group in 2, 2' positions of the mesogenic core produce polymers withlower transition temperatures. Polymers synthesized from ortho and meta substituted phenylenediamine did not form a liquid crystal phase.展开更多
The separation of aromatics from aliphatics is essential for achieving maximum exploitation of oil resources in the petrochemical industry.In this study,a series of metal chloride-based ionic liquids were prepared and...The separation of aromatics from aliphatics is essential for achieving maximum exploitation of oil resources in the petrochemical industry.In this study,a series of metal chloride-based ionic liquids were prepared and their performances in the separation of 1,2,3,4-tetrahydronaphthalene(tetralin)/dodecane and tetralin/decalin systems were studied.Among these ionic liquids,1-ethyl-3-methylimidazolium tetrachloroferrate([EMIM][FeCl_(4)])with the highest selectivity was used as the extractant.Density functional theory calculations showed that[EMIM][FeCl_(4)]interacted more strongly with tetralin than with dodecane and decalin.Energy decomposition analysis of[EMIM][FeCl_(4)]-tetralin indicated that electrostatics and dispersion played essential roles,and induction cannot be neglected.The van der Waals forces was a main effect in[EMIM][FeCl_(4)]-tetralin by independent gradient model analysis.The tetralin distribution coefficient and selectivity were 0.8 and 110,respectively,with 10%(mol)tetralin in the initial tetralin/dodecane system,and 0.67 and 19.5,respectively,with 10%(mol)tetralin in the initial tetralin/decalin system.The selectivity increased with decreasing alkyl chain length of the extractant.The influence of the extraction temperature,extractant dosage,and initial concentrations of the system components on the separation performance were studied.Recycling experiments showed that the regenerated[EMIM][FeCl_(4)]could be used repeatedly.展开更多
Crystalline morphology in a series of CH_(3)-substituted main chain thermotropic aromatic polyesters with even and odd numbered methylene spacers has been studied by polarizing optical microscopy(POM),scanning electro...Crystalline morphology in a series of CH_(3)-substituted main chain thermotropic aromatic polyesters with even and odd numbered methylene spacers has been studied by polarizing optical microscopy(POM),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).On crystallization from solution evaporation spherulites of radial structure were observed in the polymers with even numbered spacers,but spherulites with concentric rings form in the polymer with odd numbered spacers.Both spherulites have a lamellar structure,which is about 10 nm in thickness.On crystallization from nematic glassy state spherulites can not be grown;lamellar structure was only observed around disclinations in a specimen during crystallization.Ln the case of crystallization from nematic melt two types of spherulites can be observed far the sample with even numbered spacers.For the sample with add numbered spacers spherulites can not be formed,but only irregular crystallites.展开更多
A series organosoluble and heterocyclic poly（ether-amide）s （PEA）s were synthesized from a new diamine containing pyridine moiety and four aliphatic-aromatic dicarboxylic acids by direct polycondensation reactions....A series organosoluble and heterocyclic poly（ether-amide）s （PEA）s were synthesized from a new diamine containing pyridine moiety and four aliphatic-aromatic dicarboxylic acids by direct polycondensation reactions. Dicarboxilic acids 4a-4d containing ether groups were synthesized in two step reactions. At first, dialdehydes 3a-3d were synthesized from four dibromo alkanes la-ld and 4-hydroxybenzaldehyde 2, then dicarboxilic acids 4a-4d were synthesized from dialdehydes 3a-3d and malonic acid in a solvent free reaction. On the other hand, the new diamine 8 containing pyridine ring was synthesized in two step reactions. The structures of synthesized monomers and polymers were proven by FTIR, NMR spectroscopy and elemental analysis. Also all of the above polymers were fully characterized by inherent viscosity, solubility tests, gel permeation chromatography （GPC）, differential scanning calorimetry （DSC） and thermogravimetric analysis （TGA）. The resulted PEAs have shown good inherent viscosities, solubility and thermal properties.展开更多
Eggshell powder is a powdered product that is made from discarded eggshells. It is rich in inorganic salts and a small number of organic substances. Aliphatic polyester is one of the most promising polymer materials a...Eggshell powder is a powdered product that is made from discarded eggshells. It is rich in inorganic salts and a small number of organic substances. Aliphatic polyester is one of the most promising polymer materials at present. Aliphatic polyester has not only a wide range of sources, but also excellent biodegradability and biocompatibility. Three kinds of aliphatic polyester composites were mixed with PCL, PBS, PHA, PLA and Ag powder as raw materials through solution reinforcement by eggshell powder. The thermal properties and structures of the three materials were analyzed and characterized by differential scanning calorimetry and scanning electron microscopy. DSC and SEM were used to analyze and characterize the thermal properties and structures of the three composites. The experimental results show that the GTT(glass-transition temperature) are 91.9°C, 89.3°C, and 87.2°C, the melting points are all greater than 92°C, and the enthalpy changes are respectively -37.8J/g, -23.9J/g, -22.2 J/g,. Among them, the composite material of PCL, PBS and eggshell powder, and Ag powder has excellent performance, showing good thermal performance and thermal stability. Moreover, the production and utilization of eggshell powder, turning waste into wealth, has important economic value for the sustainable development of circular ecology.展开更多
Aliphatic polyesters and polycarbonates are among the promising sustainable polymers,which exhibit unique degradability and chain-chain interactions owing to their heterofunctionality.However,monocomponent aliphatic p...Aliphatic polyesters and polycarbonates are among the promising sustainable polymers,which exhibit unique degradability and chain-chain interactions owing to their heterofunctionality.However,monocomponent aliphatic polyesters and polycarbonates usually suffer from inferior properties and functionalities.By contrast,precisely modulated block copolymers composed of polyesters and polycarbonates give rise to sustainable materials with tailored performance.An efficient approach to synthesize the block copolymers is the ring-opening(co)polymerization of the heterocycle monomers.Herein,this review presents the heterocycle monomer ring-opening(co)polymerization for the formation of sequence-controlled block polyesters and polycarbonates.Available synthetic strategies,different monomers,monomer combinations and the catalyst systems for the formation of different block polyesters and polycarbonates are summarized.展开更多
The effects of the structure of typical cations and anions of ionic liquids on the separation of benzene and toluene from aromatic/paraffin mixtures were studied. The .results showed that the corresponding separation ...The effects of the structure of typical cations and anions of ionic liquids on the separation of benzene and toluene from aromatic/paraffin mixtures were studied. The .results showed that the corresponding separation factors were considerably larger than those of the traditional solvents （Benzene＋Hexane＋sulfolane）, and that the ionic liquids could be used as novel solvents for the separation of aromatics from hydrocarbon mixtures. The key parameters governing the ability of ionic liquids for separating aromatics from hydrocarbon sources were investigated. It was found that the effectiveness of the ionic liquids, based on the same anion, changed in the cation order of [BIqu]^＋〈 [BPy]^＋〈 [BMIM]^＋. The selectivity of the ionic liquid toward aromatics decreased apparently with the increasing length of the substituted alkyl chain of its cationic head ring. The separation factors, based on the same cation, changed in the anion order of [Tf2N]^-〈[PF6]^-〈[BF4]^-〈[C2H5SO4]^-. The solubilities of the aromatics were greater in the ionic liquids based on the former three anions than that in the ionic liquids involving [C2H5SO4]^-.展开更多
Sorption by biodegradable polyesters of several aromatic chemicals as model compounds for hydrophobic organic contaminants (HOCs) was studied. The biodegradable polyesters used were poly(butylene succinate), poly(3-hy...Sorption by biodegradable polyesters of several aromatic chemicals as model compounds for hydrophobic organic contaminants (HOCs) was studied. The biodegradable polyesters used were poly(butylene succinate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(ε-caprolactone), poly(butylene succinate/ terephthalate), and poly(L-lactic acid). Petrochemical plastics, low-density polyethylene and polyethylene terephtalate, were used for comparison. The target HOCs were biphenyl, bisphenol-A, dibenzofuran, diethylstilbestrol, nonyl-phenol, and chlorophenols. The treatment of the HOC solutions with each of the biodegradable polyesters resulted in the nearly complete removal of the chemicals by sorption from the aqueous phase, except for the case of poly(L-lactic acid). Low-density polyethylene adsorbed biphenyl and dibenzofuran selectively, and polyethylene terephtalate did not adsorb any of the HOCs. The adsorptive interaction between the plastics and the HOCs might be related to both the glass transition temperature of the former and the nature of the latter as defined by the Fujita's inorganicity/organicity ratio. The toxic effect of 3,5-dichlorophenol on bacte-rial growth in liquid culture was removed by the addition of a biodegradable polyester. These results provide a basis for the applicability of the biodegradable plastics as the adsorbents for the removal of HOCs from aquatic environments.展开更多
基金support from the Natural Science Foundation of Ningbo(No.2007A610030)Science and Technology Department of Zhejiang Province(No.2008C11092-2)
文摘In situ melt polycondensation was proposed to prepare biodegradable aliphatic-aromatic copolyesters/nano-SiO2 hybrids based on terephthalic acid （TPA）, poly（L-lactic acid） oligomer （OLLA）, 1,4-butanediol （BDO） and nano-SiO2. TEM and FT-IR characterizations confirmed that TPA, OLLA and BDO copolymerized to obtain biodegradable copolyesters, poly（butylene terepbthalate-co-lactate） （PBTL）, and the abundant hydroxyl groups on the surface of nano-SiO2 provided potential sites for in situ grafting with the simultaneous resulted PBTL. The nano-SiO2 particles were chemically wrapped with PBTL to form PBTL/nano- SiO2 hybrids. Due to the good dispersion and interfacial adhesion of nano-SiO2 particles with the copolyester matrix, the tensile strength and the Young＇s modulus increased from 5.4 and 5.6 MPa for neat PBTL to 16 and 390 MPa for PBTL/nano-SiO2 hybrids with 5 wt.% nano-SiO2, respectively. The mechanical properties of PBTL/nano-SiO2 hybrids were substantially improved.
文摘A series of biodegradable aliphatic-aromatic copolyesters, poly(butylene terephthalate-co-butylene adipate-co- ethylene terephthalate-co-ethylene adipate) (PBATE), were synthesized from terephthalic acid (PTA), adipic acid (AA), 1,4-butanediol (BG) and ethylene glycol (EG) through direct esterification and polycondensation. The sequence structure and crystallinity of the copolyester were investigated by 1H NMR spectroscopy and the wide-angle X-ray diffractometry (WAXD). The analytical results showed that the PBATE copolyester was a random copolymer and the composition of PBATE copolyester was almost consistent with the feed molar ratios. The crystal structure of PBATE copolyester belonged to the triclinic crystalline system; The variation in melting point of the synthesized PBATE copolyester agreed well with the estimation obtained by the Flory equation and was applicable to the random copolymer.
基金supported by the Natural Science Foundation of Ningbo(No.2007A610030)Scientific Special Fund of Zhejiang Province(No.2008C11092-2)
文摘Biodegradable aliphatic/aromatic copolyesters, poly（butylene terephthalate-co-lactate） （PBTL） were prepared via direct melt polycondensation of terephthalic acid （TPA）, 1,4-butanediol （BDO） and poly（L-lactic acid） oligomer （OLLA）. The effects of polymerization time and temperature, as well as aliphatic/aromatic moiety ratio on the physical and thermal properties were investigated. The largest molecular weight of the copolyesters was up to 64100 with molecular weight distribution index of 2.09 when the polycondensation was carried out at 230℃ for 6 h. DSC, XRD, DMA and TGA analysis clearly indicated that the degree of crystallinity, glass-transition temperature, melting point, decomposition temperature, tensile strength, elongation and Young＇s modulus were influenced by the ratio between TPA and OLLA in the final copolyesters. Hydrolytic degradation results demonstrated that the incorporation of biodegradable lactate moieties into the aromatic polyester could efficiently improve hydrolytic degradability of the copolymer even though it still had many aromatic units in the main chains.
基金financially supported by the National Natural Science Foundation of China(Nos.22071016 and 21920102006)。
文摘The asymmetric alternating copolymerization of meso-epoxide and cyclic anhydrides provides an efficient access to enantiopure polyesters.Contrary to the extensive investigation of the stereochemistry resulting from epoxide building block,the chirality from anhydride and the configurational match with epoxide remain elusive.Herein,we discover that the bimetallic chromium catalysts have led to an obvious enhancement in terms of reactivity and enantioselectivity for the asymmetric copolymerization of meso-epoxide with various non-symmetric chiral anhydrides.Up to 97%ee was obtained during the asymmetric copolymerization of cyclohexene oxide(CHO)with(R)-methylsuccinic anhydride(R-MSA),and three-or four-carbon chiral centers were simultaneously installed in the aliphatic polyester backbone.In particular,the different combinations of stereochemistry in epoxide and anhydride building blocks considerably affect the thermal properties and crystalline behaviors of the resulting polyesters.This study uncovers an interesting method for regulating polymer crystallinity via matching the chirality of different monomers.
基金The project is supported by the EPSRC and the Youth Science Foundation of Shanghai Higher Education.
文摘An epoxy-terminated hyperbranched aromatic polyester (P3) was synthesized from a hyperbranched aromatic polyester containing carboxylic acid end groups (P1), which was derived from the condensation polymerization of the AB(2) monomer, 5-acetoxyisophthalic acid. Polymer P1 was converted into the polymeric acid chloride by reaction with thionyl chloride. The acid chloride was reacted with ethanol and glycidol to form a poly(ethyl ester) (P2) and an epoxy terminated material (P3), respectively. The reaction conditions in each step of these processes had to be controlled very carefully to avoid unwanted cross-linking reactions. The characterization of products and intermediates, including molecular weight distributions and thermal properties, are reported.
基金Supported by the National Natural Science Foundation of China(21406006,21576003)the Science and Technology Program of Beijing Municipal Education Commission(KM201510005010)+1 种基金the Importation and Development of High-Caliber Talents Project of Beijing Municipal Institutions(CIT&TCD20150309)the China Postdoctoral Science Foundation funded project(2015M580954)
文摘The separation of aromatic/aliphatic hydrocarbon mixtures is a significant process in chemical industry, but challenged in some cases. Compared with conventional separation technologies, pervaporation is quite promising in terms of its economical, energy-saving, and eco-friendly advantages. However, this technique has not been used in industry for separating aromatic/aliphatic mixtures yet. One of the main reasons is that the separation performance of existed pervaporation membranes is unsatisfactory. Membrane material is an important factor that affects the separation performance. This review provides an overview on the advances in studying membrane materials for the pervaporation separation of aromatic/aliphatic mixtures over the past decade. Explored pristine polymers and their hybrid materials(as hybrid membranes) are summarized to highlight their nature and separation performance. We anticipate that this review could provide some guidance in the development of new materials for the aromatic/aliphatic pervaporation separation.
基金financially supported by the National Natural Science Foundation of China (22178008, 22125801)Petrochina (2022DJ6004)。
文摘The separation of aromatic/aliphatic hydrocarbon mixtures is crucial in the petrochemical industry.Pervaporation is regarded as a promising approach for the separation of aromatic compounds from alkanes. Developing membrane materials with efficient separation performance is still the main task since the membrane should provide chemical stability, high permeation flux, and selectivity. In this study, the hyperbranched polymer(HBP) was deposited on the outer surface of a polyvinylidene fluoride(PVDF)hollow-fiber ultrafiltration membrane by a facile dip-coating method. The dip-coating rate, HBP concentration, and thermal cross-linking temperature were regulated to optimize the membrane structure.The obtained HBP/PVDF hollow-fiber-composite membrane had a good separation performance for aromatic/aliphatic hydrocarbon mixtures. For the 50%/50%(mass) toluene/n-heptane mixture, the permeation flux of optimized composite membranes could reach 1766 g·m^(-2)·h^(-1), with a separation factor of 4.1 at 60℃. Therefore, the HBP/PVDF hollow-fiber-composite membrane has great application prospects in the pervaporation separation of aromatic/aliphatic hydrocarbon mixtures.
文摘Aliphatic polyesters were synthesized via the ring opening polymerization of the corresponding lactones initiated with dibutylmagnesium both in bulk and in solution. The resulting polymers were characterized by 1H, 13C NMR, GPC and XRD. The results indicated that dibutylmagnesium is an effective initiator for the ring opening polymerization of lactones.
文摘The crystalline morphology of a thermotropic aromatic polyester has been studied by microscopy techniques. Spherulites with ringed structure under polarizing micioscope were observed for solution cast specimens, They were composed of radially growing crystalline lamellae of thickness around 100. It was found that the molecules were packed in the thickness direction. Banded texture was observed in randomly packed domains for melt cast specimens. The bands have the same width and internal structure as those usually observed in oriented specimens of these polymers obtained by shearing their mesomorphic melt.
文摘Infrared spectra at different temperatures have been studied for fractions ofa liquid crystal tormmg aromatic polyester. The molecular interactions in different phases and their changes duringthe transitions were discussed. Abrupt frequency shift was found for bands of groups both in mesogens and flexible spacers during fusion and isotropization transitions. It may imply that both the mesogens and the flexible spacers are included in the same crystalline phase and give their contributions to the formation of the mesophase. The splitting into doublet of the C—O stretching vibrations was observed for both the aromatic and aliphatic esters and was attributed to the existence of local regions for ester groups different in ordering. The more ordered regions do not disappear completely even in the isotropic liquid phase.
文摘Six new polyesters 7a-f were synthesized through the solution polycondensation reaction of diacid chloride 5 with six aromatic diols 6a-f in N,N-dimethyl acetamide(DMAc) as solvent in the presence of pyridine as base.The polycondensation reaction produced a series of novel polyester containing pyridyl moiety in the main chain in high yields with inherent viscosities between 0.35 and 0.54 dL/g.The resulted polymers were fully characterized by means of FT-IR spectroscopy,elemental analyses,inherent viscosity ...
文摘Six aromatic polyesters were prepared for gas separation membranes, and their permeation properties for hydrogen, oxygen, nitrogen, carbon dioxide, and methane were measured at 30 degrees C and 1 atmosphere by low pressure manometric method. The correlation between the gas transport behavior and molecular structure of aromatic polyester membrane is discussed. These data are interpreted qualitatively in terms of the calculated packing density, gas-polymer interaction, concentration of aryl bromine on backbone, and effect of silane group on main chain of polymer.
文摘Polyesters consisting of substituted aromatic type Schiff base mesogenic unit andpolymethylene spacers were synthesized and their thermal transitions and liquid crystallineproperties were studied. The liquid crystalline behaviour has been characterized by differentialscanning calorimetry (DSC) and optical polarizing microscopy. Structural broadening bysubstitution of methoxy group in 2, 2' positions of the mesogenic core produce polymers withlower transition temperatures. Polymers synthesized from ortho and meta substituted phenylenediamine did not form a liquid crystal phase.
基金supported by the National Natural Science Foundation of China(22125802,22078010).
文摘The separation of aromatics from aliphatics is essential for achieving maximum exploitation of oil resources in the petrochemical industry.In this study,a series of metal chloride-based ionic liquids were prepared and their performances in the separation of 1,2,3,4-tetrahydronaphthalene(tetralin)/dodecane and tetralin/decalin systems were studied.Among these ionic liquids,1-ethyl-3-methylimidazolium tetrachloroferrate([EMIM][FeCl_(4)])with the highest selectivity was used as the extractant.Density functional theory calculations showed that[EMIM][FeCl_(4)]interacted more strongly with tetralin than with dodecane and decalin.Energy decomposition analysis of[EMIM][FeCl_(4)]-tetralin indicated that electrostatics and dispersion played essential roles,and induction cannot be neglected.The van der Waals forces was a main effect in[EMIM][FeCl_(4)]-tetralin by independent gradient model analysis.The tetralin distribution coefficient and selectivity were 0.8 and 110,respectively,with 10%(mol)tetralin in the initial tetralin/dodecane system,and 0.67 and 19.5,respectively,with 10%(mol)tetralin in the initial tetralin/decalin system.The selectivity increased with decreasing alkyl chain length of the extractant.The influence of the extraction temperature,extractant dosage,and initial concentrations of the system components on the separation performance were studied.Recycling experiments showed that the regenerated[EMIM][FeCl_(4)]could be used repeatedly.
基金This work was supported by the National Key Prject of Fundamental Research"Maromolcular Condensed State"Ministy of Scicncc and Technology,China and by Polymer Physics Laboratory,Chinesec Academy of Science.
文摘Crystalline morphology in a series of CH_(3)-substituted main chain thermotropic aromatic polyesters with even and odd numbered methylene spacers has been studied by polarizing optical microscopy(POM),scanning electron microscopy(SEM)and transmission electron microscopy(TEM).On crystallization from solution evaporation spherulites of radial structure were observed in the polymers with even numbered spacers,but spherulites with concentric rings form in the polymer with odd numbered spacers.Both spherulites have a lamellar structure,which is about 10 nm in thickness.On crystallization from nematic glassy state spherulites can not be grown;lamellar structure was only observed around disclinations in a specimen during crystallization.Ln the case of crystallization from nematic melt two types of spherulites can be observed far the sample with even numbered spacers.For the sample with add numbered spacers spherulites can not be formed,but only irregular crystallites.
文摘A series organosoluble and heterocyclic poly（ether-amide）s （PEA）s were synthesized from a new diamine containing pyridine moiety and four aliphatic-aromatic dicarboxylic acids by direct polycondensation reactions. Dicarboxilic acids 4a-4d containing ether groups were synthesized in two step reactions. At first, dialdehydes 3a-3d were synthesized from four dibromo alkanes la-ld and 4-hydroxybenzaldehyde 2, then dicarboxilic acids 4a-4d were synthesized from dialdehydes 3a-3d and malonic acid in a solvent free reaction. On the other hand, the new diamine 8 containing pyridine ring was synthesized in two step reactions. The structures of synthesized monomers and polymers were proven by FTIR, NMR spectroscopy and elemental analysis. Also all of the above polymers were fully characterized by inherent viscosity, solubility tests, gel permeation chromatography （GPC）, differential scanning calorimetry （DSC） and thermogravimetric analysis （TGA）. The resulted PEAs have shown good inherent viscosities, solubility and thermal properties.
文摘Eggshell powder is a powdered product that is made from discarded eggshells. It is rich in inorganic salts and a small number of organic substances. Aliphatic polyester is one of the most promising polymer materials at present. Aliphatic polyester has not only a wide range of sources, but also excellent biodegradability and biocompatibility. Three kinds of aliphatic polyester composites were mixed with PCL, PBS, PHA, PLA and Ag powder as raw materials through solution reinforcement by eggshell powder. The thermal properties and structures of the three materials were analyzed and characterized by differential scanning calorimetry and scanning electron microscopy. DSC and SEM were used to analyze and characterize the thermal properties and structures of the three composites. The experimental results show that the GTT(glass-transition temperature) are 91.9°C, 89.3°C, and 87.2°C, the melting points are all greater than 92°C, and the enthalpy changes are respectively -37.8J/g, -23.9J/g, -22.2 J/g,. Among them, the composite material of PCL, PBS and eggshell powder, and Ag powder has excellent performance, showing good thermal performance and thermal stability. Moreover, the production and utilization of eggshell powder, turning waste into wealth, has important economic value for the sustainable development of circular ecology.
基金supported by the National Natural Science Foundation of China,Fund for Distinguished Young Scholars(No.52325301)CAS Project for Young Scientists in Basic Research(YSBR-094)the National Natural Science Foundation of China,Basic Science Center Program(No.51988102).
文摘Aliphatic polyesters and polycarbonates are among the promising sustainable polymers,which exhibit unique degradability and chain-chain interactions owing to their heterofunctionality.However,monocomponent aliphatic polyesters and polycarbonates usually suffer from inferior properties and functionalities.By contrast,precisely modulated block copolymers composed of polyesters and polycarbonates give rise to sustainable materials with tailored performance.An efficient approach to synthesize the block copolymers is the ring-opening(co)polymerization of the heterocycle monomers.Herein,this review presents the heterocycle monomer ring-opening(co)polymerization for the formation of sequence-controlled block polyesters and polycarbonates.Available synthetic strategies,different monomers,monomer combinations and the catalyst systems for the formation of different block polyesters and polycarbonates are summarized.
基金The authors thank the National Natural Science Foundation of China(20276037)the CNPC Innovation Foundation(03E7016)for financial support.
文摘The effects of the structure of typical cations and anions of ionic liquids on the separation of benzene and toluene from aromatic/paraffin mixtures were studied. The .results showed that the corresponding separation factors were considerably larger than those of the traditional solvents （Benzene＋Hexane＋sulfolane）, and that the ionic liquids could be used as novel solvents for the separation of aromatics from hydrocarbon mixtures. The key parameters governing the ability of ionic liquids for separating aromatics from hydrocarbon sources were investigated. It was found that the effectiveness of the ionic liquids, based on the same anion, changed in the cation order of [BIqu]^＋〈 [BPy]^＋〈 [BMIM]^＋. The selectivity of the ionic liquid toward aromatics decreased apparently with the increasing length of the substituted alkyl chain of its cationic head ring. The separation factors, based on the same cation, changed in the anion order of [Tf2N]^-〈[PF6]^-〈[BF4]^-〈[C2H5SO4]^-. The solubilities of the aromatics were greater in the ionic liquids based on the former three anions than that in the ionic liquids involving [C2H5SO4]^-.
文摘Sorption by biodegradable polyesters of several aromatic chemicals as model compounds for hydrophobic organic contaminants (HOCs) was studied. The biodegradable polyesters used were poly(butylene succinate), poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(ε-caprolactone), poly(butylene succinate/ terephthalate), and poly(L-lactic acid). Petrochemical plastics, low-density polyethylene and polyethylene terephtalate, were used for comparison. The target HOCs were biphenyl, bisphenol-A, dibenzofuran, diethylstilbestrol, nonyl-phenol, and chlorophenols. The treatment of the HOC solutions with each of the biodegradable polyesters resulted in the nearly complete removal of the chemicals by sorption from the aqueous phase, except for the case of poly(L-lactic acid). Low-density polyethylene adsorbed biphenyl and dibenzofuran selectively, and polyethylene terephtalate did not adsorb any of the HOCs. The adsorptive interaction between the plastics and the HOCs might be related to both the glass transition temperature of the former and the nature of the latter as defined by the Fujita's inorganicity/organicity ratio. The toxic effect of 3,5-dichlorophenol on bacte-rial growth in liquid culture was removed by the addition of a biodegradable polyester. These results provide a basis for the applicability of the biodegradable plastics as the adsorbents for the removal of HOCs from aquatic environments.
