A diamine containing ether and ester units, as basic monomer for the preparation of polyamides, was prepared via three consecutive reactions. Nucleophilic substitution reaction of 1,4-dihydroxy benzene with 4-nitroben...A diamine containing ether and ester units, as basic monomer for the preparation of polyamides, was prepared via three consecutive reactions. Nucleophilic substitution reaction of 1,4-dihydroxy benzene with 4-nitrobenzoyl chloride produced 4-hydroxyphenyl 4-nitrobenzoate (HPNB). Reduction of nitro groups to amino groups using Fe and HC1 resulted in preparation of 4-hydroxyphenyl 4-aminobenzoate (HPAB). The diamine was synthesized through nucleophilic substitution reaction of HPAB with 2,6-dichloropyridine. The precursors and diamine were fully characterized by common methods, and the diamine was polycondensed with different diacid chlorides in the presence of an acid scavenger to prepare new polyamides. The polyamides were characterized, and their physical properties including thermal stability and behavior, inherent viscosity and solubility were studied.展开更多
Long chain semiaromatic polyamides with high molecular weight were synthesized by the reactions of undecanediamine with various aromatic diacids,and characterized by fourier transform infrared spectra(FT-IR) and nuc...Long chain semiaromatic polyamides with high molecular weight were synthesized by the reactions of undecanediamine with various aromatic diacids,and characterized by fourier transform infrared spectra(FT-IR) and nuclear magnetic resonance(1H-NMR).The thermal behaviors were determined by differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA).The solubility,dynamic mechanical,physical and mechanical properties of the polyamides were also investigated.The experimental results show that the polyamides with high molecular weights are obtained only the PH value of the polyamides salt are in the range of 7.2-7.4.The melting temperatures and the glass transition temperatures of the polyamides increase with the increase of the rigidity of aromatic diacids,and are near to those of poly(nonamethylenetere-phthalamide)(PA9T).展开更多
New unsymmetrical diamine monomer containing triaryl imidazole pendent group, 4-[4-(4,5-diphenyl-1H-imidazol-2-y1)phe- noxy]-1,3-benzenediamine, was synthesized via aromatic substitution reaction of 1-chloro-2,4-din...New unsymmetrical diamine monomer containing triaryl imidazole pendent group, 4-[4-(4,5-diphenyl-1H-imidazol-2-y1)phe- noxy]-1,3-benzenediamine, was synthesized via aromatic substitution reaction of 1-chloro-2,4-dinitrobenzene with 4-(4,5- diphenyl-1H-imidazol-2-y1)pbenol, followed by palladium-catalyzed hydrazine reduction. This new monomer was further confirmed by FT-IR, IH NMR and ^13C NMR. Novel polyamides having pendant triaryl imidazole group were prepared by the phosphorylation polycondensation of four commercially aromatic dicarboxylic acids with the prepared diamine. Inherent viscosities of polyamides were in the range 0.42-0.53 dL/g indicating formation of medium molecular weight polymers. Polyamides exhibited glass-transition temperature (Tg) in the range 236-265 ℃. These polymers are essentially amorphous and were soluble in polar aprotic solvents such as DMF, NMP, DMAc. The 10% weight loss temperatures in air atmosphere, measured by TGA were in the range 350-373 ℃ indicating their good thermal stabilities. ?2009 Mousa Ghaemy. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.展开更多
The preliminary results for one-pot synthesis of dendronized aromatic polyamides with chloromethyl groups in the periphery by approach were reported first time. The GPC analysis of the resulting dendronized polymers h...The preliminary results for one-pot synthesis of dendronized aromatic polyamides with chloromethyl groups in the periphery by approach were reported first time. The GPC analysis of the resulting dendronized polymers has shown typical weight average molecular weight (Mw) of 41554 and a polydispersity of 2.74.展开更多
A series of dimer acid-based polyamides were synthesized by melt-polycondensation of dimer acid and various aromatic diamines, and were characterized by Fourier transform infrared spectrum (FT-IR) and nuclear magnet...A series of dimer acid-based polyamides were synthesized by melt-polycondensation of dimer acid and various aromatic diamines, and were characterized by Fourier transform infrared spectrum (FT-IR) and nuclear magnetic resonance (^1H NMR). The physical properties of the polyamides, such as glass transition temperature, melting temperature, decomposition temperature and mechanical properties were also investigated. The polyamides' intrinsic viscosity ranges from 1.8 dL·g^-1 to 2.2 dL·g^-1, and the melting temperature ranges from 140 ℃ to 181 ℃. The glass transition temperatures, observed from dynamic mechanical analysis, fall in the range of 34.8-48.2 ℃. The physical and mechanical properties of the resultant polyamides are similar to those of the PA1212. The heat resistance and mechanical properties of poly (4, 4′-diphenylsulfone dimeramide) (PSD) and poly(4, 4′-di pb enyl dimeramide) (PPDI) are comparable to those of PA 1212.展开更多
Aromatic copolyamides were synthesized by the Yamazaki phosphorylation method starting from bis(4- carboxyphenyl) phenyl phosphine oxide,terephthalic acid and 4,4 -diaminodiphenyl methane.The copolymers with inherent ...Aromatic copolyamides were synthesized by the Yamazaki phosphorylation method starting from bis(4- carboxyphenyl) phenyl phosphine oxide,terephthalic acid and 4,4 -diaminodiphenyl methane.The copolymers with inherent viscosities of 0.52-0.99 dL/g were obtained.The structures of the copolyamides were characterized by elemental analysis, FTIR and NMR.The glass transition temperatures were measured by DSC and DMA,respectively,and the results showed that the T_gs of the polymers were higher than 287℃.Thermal de...展开更多
A new diamine containing sulfone,sulfide and amide groups was synthesized via a three-step reaction process. The nucleophilic substitution reaction of 4-aminothiophenol with 4-nitrobenzoyl chloride in the presence of ...A new diamine containing sulfone,sulfide and amide groups was synthesized via a three-step reaction process. The nucleophilic substitution reaction of 4-aminothiophenol with 4-nitrobenzoyl chloride in the presence of propylene oxide (PO) afforded N-(4-mercaptophenyl)-4-nitrobenzamide(MPNB).The catalytic reduction of the nitro group in MPNB to amino group was accomplished by using Pd/C and hydrazine monohydrate to produce 4-amino-N-(4-mercapto phenyl)benzamide(AMPB).Reaction of two moles of AMPB with bis(4-c...展开更多
Aromatic/aliphatic polyamides were synthesized from a diamine monomer, 2,3-bis-p-aminophenylquinoxaline (IV), based on quinoxaline and various dicarboxylic acids of aliphatic, aromatic and heterocyclic. The diamine ...Aromatic/aliphatic polyamides were synthesized from a diamine monomer, 2,3-bis-p-aminophenylquinoxaline (IV), based on quinoxaline and various dicarboxylic acids of aliphatic, aromatic and heterocyclic. The diamine and polyamides were characterized by elemental analysis, FTIR and IH-NMR. The solubility of the polyamides was affected by the quinoxaline and heterocyclic groups in the polymer chain. They were all soluble in common organic solvents such as dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF) and N-methylpyrolidone (NMP). The polyamides showed inherent viscosity in the range of 0.25-0.3 dL/g in DMSO at 25℃ and good thermal stability with the char yields in the range of 65%-82% at 600℃ in nitrogen.展开更多
A novel unsymmetrical fluorinated diamine monomer with kink non-coplanar heterocyclic structures, 1,2-dihydro- 2-(4-amino-2-trifluoromethyophenyo)-4-[4-(4-amino-2-trifluoromethyophenoxy)phenyo](2H)phthaoazin-1-o...A novel unsymmetrical fluorinated diamine monomer with kink non-coplanar heterocyclic structures, 1,2-dihydro- 2-(4-amino-2-trifluoromethyophenyo)-4-[4-(4-amino-2-trifluoromethyophenoxy)phenyo](2H)phthaoazin-1-oneo was prepared through the nucleophilic substitution reaction of 1-trifluromethyl-2-chloro-5-nitrobenzene with 1,2-dihydro-4-(4- hydroxyphenyl)(2H)phthalazin-l-one in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd-C. A series of new fluorinated polyarnides were synthesized by the phosphorylation polyamidation of the fluorinated diamine with various dicarboxylic acids. The prepared polymers were obtained in quantitative yields with moderately and high inherent viscosities (0.47-0.87 dL/g). They were all amorphous and readily soluble in various polar aprotic solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacctamide (DMAc), pyridine (Py) and m-cresol at room temperature. These fluorinated polyamides have excellent thermal properties. The glass transition temperatures were all above 300℃. The 5% and 10% weight loss temperatures were in the range of 437-466℃ and 482-525℃ in nitrogen atmosphere, respectively.展开更多
A series of novel mesogenic polyamides containing a flexible pendent side group was synthesized by solution condensation polymerization. The new monomers, diacids and diamines containing flexible elements of different...A series of novel mesogenic polyamides containing a flexible pendent side group was synthesized by solution condensation polymerization. The new monomers, diacids and diamines containing flexible elements of different lengths, were also synthesized and characterized by H-1 NMR, mass spectroscopy and elemental analysis. The polymers were characterized by viscosity measurements, differential scanning calorimetry (DSC), X-ray diffraction and polarizing optical microscopy. These studies revealed that polyamides containing flexible elements of a sufficient length exhibited thermotropic liquid crystalline (LC) properties. The melting temperatures of this series of polymers were: particularly sensitive to the length of the flexible segment on the main chain and that of the flexible pendent ester side chain. Lyotropic LC behaviours were also observed in solution.展开更多
A new synthetic route to polyamides and hydroxyl polyamides was established, based on the selecting (?)-acylation of three novel typical active diesters: the active diester of N-hydroxy- (?) 4-epoxy-5-cyclohexene-2, 3...A new synthetic route to polyamides and hydroxyl polyamides was established, based on the selecting (?)-acylation of three novel typical active diesters: the active diester of N-hydroxy- (?) 4-epoxy-5-cyclohexene-2, 3-dicarboximide( HOEC), such as N, N'-(temphthaloyldioxy) bis(1, 4- epoxy - 5 - cyclohexene- 2, 3 - dicarboximide.) ( PBOEC), N, N'- ( isophthaloyl - dioxy) bis (1,4-epoxy-5-cyclohexene-2, 3-dicarboximide)(IPBOEC) and N, N' -(adipoyldioxy) his (1,4-epoxy-5-cyclohexene-2, 3-dicarboximide) ( ADOEC)with aliphatic diamines and 1,3-diamino-2-hydroxypropane. The polycondensation occurs at room temperature in solution without added catalyst. Dipolar aprotic solvents which include dimethyl sulfoxide, N- methyl - 2- pyrrolidone and dimethylformamide were used as solvents for polymerization. The selective N-acylation of two active diesters was performed as a model reaction study.展开更多
Electrochemical CO_(2) reduction reaction(CO_(2) RR) has attracted growing attention in energy storage and sustainable production of fuels and chemicals. N-doped carbon materials are preferred metal-free electrocataly...Electrochemical CO_(2) reduction reaction(CO_(2) RR) has attracted growing attention in energy storage and sustainable production of fuels and chemicals. N-doped carbon materials are preferred metal-free electrocatalysts, but it remains one challenge to finely engineer the active sites and porosity. Herein, we demonstrated that ionic porous polyamides were a kind of versatile precursors to prepare functional carbon materials in a one-step pyrolysis process. The polyamide precursors allowed the maintenance of abundant N species at high temperatures. The existence of ionic moieties and large specific surface area of the precursors promoted the formation of larger porosity carbon with a large specific surface area and sufficient active graphitic-N species by controlling the pyrolysis temperature. The catalyst was highly selective in the CO_(2) RR to produce CO with a maximum Faraday efficiency above 99%, attributable to the improved mass transfer in a large porosity system. This work shows that ionic polyamides are promising carbon precursors for the fabrication of metal-free electrocatalysts for CO_(2) RR.展开更多
Polyamides with chiral environment were obtained from aromatic diamine, 1,3-phenylenediamine (1,3-PDA) or 1,4- phenylenediamine (1,4-PDA), and N-α-benzoyl-L-glutamic acid (Benzoyl-L-Glu). The optical rotation ([α]D)...Polyamides with chiral environment were obtained from aromatic diamine, 1,3-phenylenediamine (1,3-PDA) or 1,4- phenylenediamine (1,4-PDA), and N-α-benzoyl-L-glutamic acid (Benzoyl-L-Glu). The optical rotation ([α]D) for 1,3- PDA-Benzoyl-L-Glu was determined to be 3.7 deg cm2 g–1, while that for 1,4-PDA-Benzoyl-L-Glu to be 9.7 deg cm2 g–1. 1,3-PDA-Benzoyl-L-Glu showed adsorption selectivity toward D-Glu and its adsorption selectivity was determined to be 1.68. Contrary to this, 1,4-PDA-Benzoyl-L-Glu showed adsorption selectivity toward L-Glu and the adsorption selectivity toward L-Glu was determined to be 1.33. From those results, those two types of chiral polyamide are expected to applicable to chiral separation or chiral recognition.展开更多
In this study, the polycondensation products of a diamine anthraquinone (1,4-diamino anthraquinone) and some aliphatic diacids with different methylene numbers were synthesised. Their UV-visible spectroscopy and therm...In this study, the polycondensation products of a diamine anthraquinone (1,4-diamino anthraquinone) and some aliphatic diacids with different methylene numbers were synthesised. Their UV-visible spectroscopy and thermal properties were then characterised. The synthesis was achieved by reacting equimolar solutions of the amine and the acid halides. The structure and thermal properties of the products were characterised. FT-IR Spectra of all the three products revealed the formation of amide due to the presence of strong bands at 1565 and 3390 cm?1 assignable to C=O stretching and N-H vibrations. Differential Scanning Calorimetry revealed high melting exotherms for the products. Thermogravimetry revealed moderate thermal stabilities for Poly NAM and Poly NAS and low thermal stability for Poly NAA which indicated 5.9%, 7.1% and 61.2% weight losses at 285℃, 285℃ and 374℃ for the three products respectively. The wavelengths of maximum absorbance for the dye samples are 601.5, 591 and 589 nm respectively with absorptivity coefficients (a1cm1% ) of 11640000, 11610000 and 11560000 respectively.展开更多
Separation membrane with high flux is generally encouraged in industrial application,because of the tremendous needs for decreasing membrane areas,usage costs and space requirements.The most effective and direct metho...Separation membrane with high flux is generally encouraged in industrial application,because of the tremendous needs for decreasing membrane areas,usage costs and space requirements.The most effective and direct method for obtaining the high flux is to decrease membrane thickness.Polyamide(PA)nanofiltration membrane is conventionally prepared by the direct interfacial polymerization(IP)on substrate surface,and results in a thick PA layer.In this work,we proposed a strategy that constructing triazine-based porous organic polymer(TRZ-POP)as the interlayer to prepare the ultrathin PA nanofiltration membranes.TRZ-POP is firstly deposited on the polyethersulfone substrate,and then the formed TRZ-POP provides more adhesion sites towards PA based on its high specific surface areas.The chemical bonding between terminal amine group of TRZ-POP and the amide group of PA further improves the binding force,and strengthens the stability of PA layer.More importantly,the high porosity of TRZPOP layer causes the higher polymerization of initial PA owning to the stored sufficient amino monomer;and H-bonding interaction between amine groups of TRZ-POP and piperazine(PIP)can astrict the release of PIP.Thus,IP process is controlled,and the thinnest thickness of prepared PA layer is only<15 nm.As expected,PA/TRZ-POP membrane shows a more excellent water flux of 1414 L·m^(-2)·h^(-1)·MPa^(-1)than that of the state-of-the-art nanofiltration membranes,and without sacrificing dye rejection.The build of TRZPOP interlayer develops a new method for obtaining a high-flux nanofiltration membrane.展开更多
For this investigation conventional polyamide 6 with monomodal molecular mass distribution, and the newly developed bimodal one were used. Conventional polyamide 6 was used as a reference material in order to emphasiz...For this investigation conventional polyamide 6 with monomodal molecular mass distribution, and the newly developed bimodal one were used. Conventional polyamide 6 was used as a reference material in order to emphasize prospects of using bimodal material for medical applications from the point of view of sterilization resistance and improved creep behavior. Time-dependent mechanical properties of testing samples were characterized by torsional creep measurements in non-sterilized state and after sterilization with three different techniques: with autoclave, ethylene oxide, and hydrogen peroxide plasma. Results show that the two materials exhibit pronounced difference in morphology and consequently, mechanical properties. Both of them were not significantly affected by any of used sterilization techniques. However, bimodal material, originally being noticeably more time-stable in comparison to monomodal one, retains these preferences also post sterilization.展开更多
Polyamide 6 (PA6) was employed as a charring agent of intumescent flame retardant (IFR) to improve the flame retardancy of ethylene-vinyl acetate copolymer (EVA). Different processing procedures were used to regulate ...Polyamide 6 (PA6) was employed as a charring agent of intumescent flame retardant (IFR) to improve the flame retardancy of ethylene-vinyl acetate copolymer (EVA). Different processing procedures were used to regulate the localization of IFR in the EVA matrix. Localizations in which IFR was dispersed in the PA6phase or in the EVA phase were prepared. The effect of the localization of IFR on the flame retardancy of EVA was investigated. The limited oxygen index (LOI), vertical burning (UL 94) and cone calorimeter test (CCT)showed that the localization of IFR in the EVA matrix exhibited a remarkable influence on the flame retardancy.Compared with EVA/IFR, a weak improvement in the flame retardancy was observed in the EVA/PA6/IFR blend withthe localization of IFR in the PA6 phase. When IFR was regulated from the PA6 phase to the EVA matrix,a remarkable increase in the flame retardancy was exhibited. The LOI was increased from 27.8%to 32.7%, and the UL 94 vertical rating was increased from V-2 to V-0. Moreover, an approximately 41.36%decrease in the peak heat release rate was exhibited. A continuous and compact intumescent charring layer that formed in the blends with the localization of IFR in the EVA matrix should be responsible for its excellent flame retardancy.展开更多
文摘A diamine containing ether and ester units, as basic monomer for the preparation of polyamides, was prepared via three consecutive reactions. Nucleophilic substitution reaction of 1,4-dihydroxy benzene with 4-nitrobenzoyl chloride produced 4-hydroxyphenyl 4-nitrobenzoate (HPNB). Reduction of nitro groups to amino groups using Fe and HC1 resulted in preparation of 4-hydroxyphenyl 4-aminobenzoate (HPAB). The diamine was synthesized through nucleophilic substitution reaction of HPAB with 2,6-dichloropyridine. The precursors and diamine were fully characterized by common methods, and the diamine was polycondensed with different diacid chlorides in the presence of an acid scavenger to prepare new polyamides. The polyamides were characterized, and their physical properties including thermal stability and behavior, inherent viscosity and solubility were studied.
文摘Long chain semiaromatic polyamides with high molecular weight were synthesized by the reactions of undecanediamine with various aromatic diacids,and characterized by fourier transform infrared spectra(FT-IR) and nuclear magnetic resonance(1H-NMR).The thermal behaviors were determined by differential scanning calorimetry(DSC) and thermogravimetric analysis(TGA).The solubility,dynamic mechanical,physical and mechanical properties of the polyamides were also investigated.The experimental results show that the polyamides with high molecular weights are obtained only the PH value of the polyamides salt are in the range of 7.2-7.4.The melting temperatures and the glass transition temperatures of the polyamides increase with the increase of the rigidity of aromatic diacids,and are near to those of poly(nonamethylenetere-phthalamide)(PA9T).
文摘New unsymmetrical diamine monomer containing triaryl imidazole pendent group, 4-[4-(4,5-diphenyl-1H-imidazol-2-y1)phe- noxy]-1,3-benzenediamine, was synthesized via aromatic substitution reaction of 1-chloro-2,4-dinitrobenzene with 4-(4,5- diphenyl-1H-imidazol-2-y1)pbenol, followed by palladium-catalyzed hydrazine reduction. This new monomer was further confirmed by FT-IR, IH NMR and ^13C NMR. Novel polyamides having pendant triaryl imidazole group were prepared by the phosphorylation polycondensation of four commercially aromatic dicarboxylic acids with the prepared diamine. Inherent viscosities of polyamides were in the range 0.42-0.53 dL/g indicating formation of medium molecular weight polymers. Polyamides exhibited glass-transition temperature (Tg) in the range 236-265 ℃. These polymers are essentially amorphous and were soluble in polar aprotic solvents such as DMF, NMP, DMAc. The 10% weight loss temperatures in air atmosphere, measured by TGA were in the range 350-373 ℃ indicating their good thermal stabilities. ?2009 Mousa Ghaemy. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved.
文摘The preliminary results for one-pot synthesis of dendronized aromatic polyamides with chloromethyl groups in the periphery by approach were reported first time. The GPC analysis of the resulting dendronized polymers has shown typical weight average molecular weight (Mw) of 41554 and a polydispersity of 2.74.
文摘A series of dimer acid-based polyamides were synthesized by melt-polycondensation of dimer acid and various aromatic diamines, and were characterized by Fourier transform infrared spectrum (FT-IR) and nuclear magnetic resonance (^1H NMR). The physical properties of the polyamides, such as glass transition temperature, melting temperature, decomposition temperature and mechanical properties were also investigated. The polyamides' intrinsic viscosity ranges from 1.8 dL·g^-1 to 2.2 dL·g^-1, and the melting temperature ranges from 140 ℃ to 181 ℃. The glass transition temperatures, observed from dynamic mechanical analysis, fall in the range of 34.8-48.2 ℃. The physical and mechanical properties of the resultant polyamides are similar to those of the PA1212. The heat resistance and mechanical properties of poly (4, 4′-diphenylsulfone dimeramide) (PSD) and poly(4, 4′-di pb enyl dimeramide) (PPDI) are comparable to those of PA 1212.
基金supported by the National Natural Science Foundation of China (No.50203008).
文摘Aromatic copolyamides were synthesized by the Yamazaki phosphorylation method starting from bis(4- carboxyphenyl) phenyl phosphine oxide,terephthalic acid and 4,4 -diaminodiphenyl methane.The copolymers with inherent viscosities of 0.52-0.99 dL/g were obtained.The structures of the copolyamides were characterized by elemental analysis, FTIR and NMR.The glass transition temperatures were measured by DSC and DMA,respectively,and the results showed that the T_gs of the polymers were higher than 287℃.Thermal de...
文摘A new diamine containing sulfone,sulfide and amide groups was synthesized via a three-step reaction process. The nucleophilic substitution reaction of 4-aminothiophenol with 4-nitrobenzoyl chloride in the presence of propylene oxide (PO) afforded N-(4-mercaptophenyl)-4-nitrobenzamide(MPNB).The catalytic reduction of the nitro group in MPNB to amino group was accomplished by using Pd/C and hydrazine monohydrate to produce 4-amino-N-(4-mercapto phenyl)benzamide(AMPB).Reaction of two moles of AMPB with bis(4-c...
文摘Aromatic/aliphatic polyamides were synthesized from a diamine monomer, 2,3-bis-p-aminophenylquinoxaline (IV), based on quinoxaline and various dicarboxylic acids of aliphatic, aromatic and heterocyclic. The diamine and polyamides were characterized by elemental analysis, FTIR and IH-NMR. The solubility of the polyamides was affected by the quinoxaline and heterocyclic groups in the polymer chain. They were all soluble in common organic solvents such as dimethylsulfoxide (DMSO), N,N-dimethylformamide (DMF) and N-methylpyrolidone (NMP). The polyamides showed inherent viscosity in the range of 0.25-0.3 dL/g in DMSO at 25℃ and good thermal stability with the char yields in the range of 65%-82% at 600℃ in nitrogen.
基金This work was financially supported by the National Natural Science Foundation of China (No. 50673031)the Key Natural Science Foundation of Fujian Province (No. E0320003)State Key Laboratory of Polymer Physics and Chemistry in Institute of Chemistry of CAS (No. 200602).
文摘A novel unsymmetrical fluorinated diamine monomer with kink non-coplanar heterocyclic structures, 1,2-dihydro- 2-(4-amino-2-trifluoromethyophenyo)-4-[4-(4-amino-2-trifluoromethyophenoxy)phenyo](2H)phthaoazin-1-oneo was prepared through the nucleophilic substitution reaction of 1-trifluromethyl-2-chloro-5-nitrobenzene with 1,2-dihydro-4-(4- hydroxyphenyl)(2H)phthalazin-l-one in the presence of potassium carbonate, followed by catalytic reduction with hydrazine and Pd-C. A series of new fluorinated polyarnides were synthesized by the phosphorylation polyamidation of the fluorinated diamine with various dicarboxylic acids. The prepared polymers were obtained in quantitative yields with moderately and high inherent viscosities (0.47-0.87 dL/g). They were all amorphous and readily soluble in various polar aprotic solvents such as N-methyl-2-pyrrolidone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacctamide (DMAc), pyridine (Py) and m-cresol at room temperature. These fluorinated polyamides have excellent thermal properties. The glass transition temperatures were all above 300℃. The 5% and 10% weight loss temperatures were in the range of 437-466℃ and 482-525℃ in nitrogen atmosphere, respectively.
基金This work is supported by the National Natural Science Foundation of China
文摘A series of novel mesogenic polyamides containing a flexible pendent side group was synthesized by solution condensation polymerization. The new monomers, diacids and diamines containing flexible elements of different lengths, were also synthesized and characterized by H-1 NMR, mass spectroscopy and elemental analysis. The polymers were characterized by viscosity measurements, differential scanning calorimetry (DSC), X-ray diffraction and polarizing optical microscopy. These studies revealed that polyamides containing flexible elements of a sufficient length exhibited thermotropic liquid crystalline (LC) properties. The melting temperatures of this series of polymers were: particularly sensitive to the length of the flexible segment on the main chain and that of the flexible pendent ester side chain. Lyotropic LC behaviours were also observed in solution.
文摘A new synthetic route to polyamides and hydroxyl polyamides was established, based on the selecting (?)-acylation of three novel typical active diesters: the active diester of N-hydroxy- (?) 4-epoxy-5-cyclohexene-2, 3-dicarboximide( HOEC), such as N, N'-(temphthaloyldioxy) bis(1, 4- epoxy - 5 - cyclohexene- 2, 3 - dicarboximide.) ( PBOEC), N, N'- ( isophthaloyl - dioxy) bis (1,4-epoxy-5-cyclohexene-2, 3-dicarboximide)(IPBOEC) and N, N' -(adipoyldioxy) his (1,4-epoxy-5-cyclohexene-2, 3-dicarboximide) ( ADOEC)with aliphatic diamines and 1,3-diamino-2-hydroxypropane. The polycondensation occurs at room temperature in solution without added catalyst. Dipolar aprotic solvents which include dimethyl sulfoxide, N- methyl - 2- pyrrolidone and dimethylformamide were used as solvents for polymerization. The selective N-acylation of two active diesters was performed as a model reaction study.
基金support from the National Natural Science Foundation of China ( 22072065, 22178162, U1662107, and 21476109)Six talent peaks project in Jiangsu Province (JNHB-035)+1 种基金State Key Laboratory of Materials-Oriented Chemical Engineering (KL18-09)the Project of Priority Academic Program Development of Jiangsu Higher Education Institutions (PAPD)。
文摘Electrochemical CO_(2) reduction reaction(CO_(2) RR) has attracted growing attention in energy storage and sustainable production of fuels and chemicals. N-doped carbon materials are preferred metal-free electrocatalysts, but it remains one challenge to finely engineer the active sites and porosity. Herein, we demonstrated that ionic porous polyamides were a kind of versatile precursors to prepare functional carbon materials in a one-step pyrolysis process. The polyamide precursors allowed the maintenance of abundant N species at high temperatures. The existence of ionic moieties and large specific surface area of the precursors promoted the formation of larger porosity carbon with a large specific surface area and sufficient active graphitic-N species by controlling the pyrolysis temperature. The catalyst was highly selective in the CO_(2) RR to produce CO with a maximum Faraday efficiency above 99%, attributable to the improved mass transfer in a large porosity system. This work shows that ionic polyamides are promising carbon precursors for the fabrication of metal-free electrocatalysts for CO_(2) RR.
文摘Polyamides with chiral environment were obtained from aromatic diamine, 1,3-phenylenediamine (1,3-PDA) or 1,4- phenylenediamine (1,4-PDA), and N-α-benzoyl-L-glutamic acid (Benzoyl-L-Glu). The optical rotation ([α]D) for 1,3- PDA-Benzoyl-L-Glu was determined to be 3.7 deg cm2 g–1, while that for 1,4-PDA-Benzoyl-L-Glu to be 9.7 deg cm2 g–1. 1,3-PDA-Benzoyl-L-Glu showed adsorption selectivity toward D-Glu and its adsorption selectivity was determined to be 1.68. Contrary to this, 1,4-PDA-Benzoyl-L-Glu showed adsorption selectivity toward L-Glu and the adsorption selectivity toward L-Glu was determined to be 1.33. From those results, those two types of chiral polyamide are expected to applicable to chiral separation or chiral recognition.
文摘In this study, the polycondensation products of a diamine anthraquinone (1,4-diamino anthraquinone) and some aliphatic diacids with different methylene numbers were synthesised. Their UV-visible spectroscopy and thermal properties were then characterised. The synthesis was achieved by reacting equimolar solutions of the amine and the acid halides. The structure and thermal properties of the products were characterised. FT-IR Spectra of all the three products revealed the formation of amide due to the presence of strong bands at 1565 and 3390 cm?1 assignable to C=O stretching and N-H vibrations. Differential Scanning Calorimetry revealed high melting exotherms for the products. Thermogravimetry revealed moderate thermal stabilities for Poly NAM and Poly NAS and low thermal stability for Poly NAA which indicated 5.9%, 7.1% and 61.2% weight losses at 285℃, 285℃ and 374℃ for the three products respectively. The wavelengths of maximum absorbance for the dye samples are 601.5, 591 and 589 nm respectively with absorptivity coefficients (a1cm1% ) of 11640000, 11610000 and 11560000 respectively.
基金funded by National Key Research and Development Program of China (2021YFC2101202)Bingtuan Science and Technology Program (2022DB025)+3 种基金Beijing Natural Science Foundation (2222015)Hebei Province Key Research and Development Program (21327316D)China Postdoctoral Science Foundation (2021M700011)the long-term subsidy mechanism from the Ministry of Finance and the Ministry of Education of China。
文摘Separation membrane with high flux is generally encouraged in industrial application,because of the tremendous needs for decreasing membrane areas,usage costs and space requirements.The most effective and direct method for obtaining the high flux is to decrease membrane thickness.Polyamide(PA)nanofiltration membrane is conventionally prepared by the direct interfacial polymerization(IP)on substrate surface,and results in a thick PA layer.In this work,we proposed a strategy that constructing triazine-based porous organic polymer(TRZ-POP)as the interlayer to prepare the ultrathin PA nanofiltration membranes.TRZ-POP is firstly deposited on the polyethersulfone substrate,and then the formed TRZ-POP provides more adhesion sites towards PA based on its high specific surface areas.The chemical bonding between terminal amine group of TRZ-POP and the amide group of PA further improves the binding force,and strengthens the stability of PA layer.More importantly,the high porosity of TRZPOP layer causes the higher polymerization of initial PA owning to the stored sufficient amino monomer;and H-bonding interaction between amine groups of TRZ-POP and piperazine(PIP)can astrict the release of PIP.Thus,IP process is controlled,and the thinnest thickness of prepared PA layer is only<15 nm.As expected,PA/TRZ-POP membrane shows a more excellent water flux of 1414 L·m^(-2)·h^(-1)·MPa^(-1)than that of the state-of-the-art nanofiltration membranes,and without sacrificing dye rejection.The build of TRZPOP interlayer develops a new method for obtaining a high-flux nanofiltration membrane.
文摘For this investigation conventional polyamide 6 with monomodal molecular mass distribution, and the newly developed bimodal one were used. Conventional polyamide 6 was used as a reference material in order to emphasize prospects of using bimodal material for medical applications from the point of view of sterilization resistance and improved creep behavior. Time-dependent mechanical properties of testing samples were characterized by torsional creep measurements in non-sterilized state and after sterilization with three different techniques: with autoclave, ethylene oxide, and hydrogen peroxide plasma. Results show that the two materials exhibit pronounced difference in morphology and consequently, mechanical properties. Both of them were not significantly affected by any of used sterilization techniques. However, bimodal material, originally being noticeably more time-stable in comparison to monomodal one, retains these preferences also post sterilization.
基金the National Natural Science Foundation of China (No.51673059)the Science and Technology Planning Project of Henan Province (No. 212102210636)the Opening Project of Jiangxi Province Key Laboratory of Polymer Micro/Nano Manufacturing and Devices (East China University of Technology)。
文摘Polyamide 6 (PA6) was employed as a charring agent of intumescent flame retardant (IFR) to improve the flame retardancy of ethylene-vinyl acetate copolymer (EVA). Different processing procedures were used to regulate the localization of IFR in the EVA matrix. Localizations in which IFR was dispersed in the PA6phase or in the EVA phase were prepared. The effect of the localization of IFR on the flame retardancy of EVA was investigated. The limited oxygen index (LOI), vertical burning (UL 94) and cone calorimeter test (CCT)showed that the localization of IFR in the EVA matrix exhibited a remarkable influence on the flame retardancy.Compared with EVA/IFR, a weak improvement in the flame retardancy was observed in the EVA/PA6/IFR blend withthe localization of IFR in the PA6 phase. When IFR was regulated from the PA6 phase to the EVA matrix,a remarkable increase in the flame retardancy was exhibited. The LOI was increased from 27.8%to 32.7%, and the UL 94 vertical rating was increased from V-2 to V-0. Moreover, an approximately 41.36%decrease in the peak heat release rate was exhibited. A continuous and compact intumescent charring layer that formed in the blends with the localization of IFR in the EVA matrix should be responsible for its excellent flame retardancy.