Reducing the amount of aluminum chloride needed for the catalytic preparation of high quality mesophase and carbon materials is important and we have found that using terephthalic acid(PTA)as a co-catalyst serves this...Reducing the amount of aluminum chloride needed for the catalytic preparation of high quality mesophase and carbon materials is important and we have found that using terephthalic acid(PTA)as a co-catalyst serves this purpose.By adding 3%(mass fraction)AlCl_(3)and 0.9%(mass fraction)PTA to the coal tar pitch,approximately 90%mesophase was synthesized.The product(M-3-0.9)had a high stacking order(L_(c)=3.1 nm,n=10.14)and aromaticity(0.942).By adding PTA,a larger anisotropy content was produced using a smaller amount of AlCl_(3).The PTA participated in the polycondensation reaction through its own benzene ring structure to increase the catalytic activity.However,when its content was higher than 1.5%,the number of oxygen-containing groups in the product increased which was unfavorable for the aromatic lamellar stacking and gave rise to more isotropic structures.The work opens up a new way to prepare mesophase by a catalytic method.展开更多
High molecular weight poly(1,4-butylene 2,5-furandicarboxylate-co-isosorbide 2,5-furandicarboxylate)copolyesters(PBSIF-x)were synthesized via melt-polycondensation of 2,5-furandicarboxylic acid(FDCA),with varying rati...High molecular weight poly(1,4-butylene 2,5-furandicarboxylate-co-isosorbide 2,5-furandicarboxylate)copolyesters(PBSIF-x)were synthesized via melt-polycondensation of 2,5-furandicarboxylic acid(FDCA),with varying ratios of isosorbide(ISB)and 1,4-butylene glycol(BDO)catalyzed by antimony trioxide(Sb_(2)O_(3)).The PBSIF-x structures were investigated using FTIR and~1H NMR,while the GPC analysis exhibited the copolyesters molecular weights with number average molecular mass(M_n)in the range of 11079-15153 g/mol.The DSC results show that PBSIF-x copolyesters have a single glass-transition temperature(T_(g))(77.45-110.96℃),increasing with the increase in ISB content,while TGA analysis demonstrates excellent thermal stability up to 320℃.From the thermal result,properties of PBSIF-x copolyesters are found to be within the interval of their parent homologues poly(butylene 2,5-furandicarboxylate)(PBF)and poly(isosorbide 2,5-furandicarboxylate)(PIF),which confirms the aromatic/aliphatic blending within the polymer matrix for enhanced polymer stability and performance.展开更多
An efficient,simple,and convenient method for Suzuki polycondensation using a diaminocarbene palladium(Ⅱ)catalyst under aerobic conditions was developed.Reactions between aromatic diboronic acid bis(pinacol)ester and...An efficient,simple,and convenient method for Suzuki polycondensation using a diaminocarbene palladium(Ⅱ)catalyst under aerobic conditions was developed.Reactions between aromatic diboronic acid bis(pinacol)ester and different aromatic dibromides,both with electrondonating and electron-withdrawing fragments in the structure,were carried out.Various reaction conditions,such as the effect of catalyst concentration and solvent,were investigated.The molecular weight characteristics,photo-and electroluminescence properties of the synthesized polymers were studied.展开更多
This work described the preparation of easily colored meta-aramid(PMIA) copolymers from m-phenylenediamine(MPD),isophthaloyl dichloride(IPC), and 3,4′-oxydianiline(3,4′-ODA) via solution polycondensation in N,N-dime...This work described the preparation of easily colored meta-aramid(PMIA) copolymers from m-phenylenediamine(MPD),isophthaloyl dichloride(IPC), and 3,4′-oxydianiline(3,4′-ODA) via solution polycondensation in N,N-dimethylacetamide(DMAc). The novel co-PMIAs were obtained in relatively high inherent viscosities ranging from 1.32 dL/g to 2.53 dL/g, which could be easily cast into flexible films with high transparence or spun into fibers. All the newly synthesized copolymers possessed excellent thermal stabilities even better than that of commercial PMIA, with 5% weight loss temperatures higher than 430 °C in nitrogen measured by TGA and glass transition temperature of 267–277 °C measured by DSC. The cast films exhibited good mechanical properties with a tensile strength up to107 MPa and a tensile modulus up to 2.2 GPa. The resultant PMIAs also showed good solubility and better dye ability for cationic dyes.展开更多
A series of quaternary ammonium ionic liquids(ILs)were synthesized and employed as catalysts for the production of poly(isosorbide carbonate)(PIC)from diphenyl carbonate and isosorbide via a melt polycondensation proc...A series of quaternary ammonium ionic liquids(ILs)were synthesized and employed as catalysts for the production of poly(isosorbide carbonate)(PIC)from diphenyl carbonate and isosorbide via a melt polycondensation process.The relationship between the anions of the ILs and the catalytic activities was investigated,and the readily‐prepared IL tetraethylammonium imidazolate(TEAI)was found to exhibit the highest catalytic activity.After optimizing the reaction conditions,a PIC with a weight‐average molecular weight(Mw)of25600g/mol was obtained,in conjunction with an isosorbide conversion of92%.As a means of modifying the molecular flexibility and thermal properties of the PIC,poly(aliphatic diol‐co‐isosorbide carbonate)s(PAIC)s were successfully synthesized,again using TEAI,and polymers with Mw values ranging from29000to112000g/mol were obtained.13C NMR analyses determined that the PAIC specimens had random microstructures,while differential scanning calorimetry demonstrated that each of the PAICs were amorphous and had glass transition temperatures ranging from50to115°C.Thermogravimetric analyses found Td‐5%values ranging from316to332°C for these polymers.Based on these data,it is evident that the incorporation of linear or cyclohexane‐based diol repeating units changed the thermal properties of the PIC.展开更多
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
Polyurea microcapsules about 2.5 μm in diameter containing phase change material for thermal energy storage application were synthesized and characterized by interfacial polycondensation method with toluene-2,4-diiso...Polyurea microcapsules about 2.5 μm in diameter containing phase change material for thermal energy storage application were synthesized and characterized by interfacial polycondensation method with toluene-2,4-diisocyanate and ethylenediamine as monomers in an emulsion system. Hexadecane was used as a phase change material and OP, which is nonionic surfactant, and used as an emulsifier. The chemical structure and thermal behavior of the microcapsules were investigated by FTIR and thermal analysis respectively. The results show encapsulated hexadecane has a good potential as a solar energy storage material.展开更多
The increase in the residue content resulting from polycondensation would be adverse to the utilization of lignocellulose and to the quality of products obtained from liquefied lignocellulosic material.The yield of th...The increase in the residue content resulting from polycondensation would be adverse to the utilization of lignocellulose and to the quality of products obtained from liquefied lignocellulosic material.The yield of the residue formed from liquefaction and the mechanism of polycondensation were reported mainly by Lin,Yamada and Kobayashi.The major products of cellulosic liquefaction are levulinic acid and hydroxymethylfurfural（HMF） derivatives under polyhydric alcohols and phenolated compounds under phenols.The cleavage of the β-O-4 bonds is the major reaction pathway of lignin liquefaction under various liquefying reagents regardless of whether they contain acid catalysts or not.The break up compounds by decomposition are polymerized to substances with high molecular weight by polycondensation in lignocellulosic liquefaction.The molecular weight of condensed residues increases almost linearly as a function of liquefaction time at the later stage of lignocellulosic liquefaction.The longer the time required,the greater the content of new residue generated by polycondensation during the entire process of liquefaction.We conclude that the condensed residues may stem from the interaction of degraded lignin and cellulose components in wood or from the products of two major components reacting with liquefying reagents.展开更多
Ethylene glycol aluminum was prepared efficiently and characterized by FT-IR and NMR.It exhibited higher catalytic activity and had profitable effect than titanium glycolate and ethylene glycol antimony for the synthe...Ethylene glycol aluminum was prepared efficiently and characterized by FT-IR and NMR.It exhibited higher catalytic activity and had profitable effect than titanium glycolate and ethylene glycol antimony for the synthesis of poly(ethylene terephthalate)(PET).It was only used as polycondensation catalyst because it was sensitive to water.For this catalyst,the degree of esterification of the theoretical amount of water was produced up to 95%at 260℃,while the intrinsic viscosity and content of terminal carboxyl groups of the corresponding PET polyester,polymerized at 280℃,70 Pa for 39 min,was 0.87 dL/g and 23.0μmol/g,respectively.Ethylene glycol aluminum was a promising catalyst for the synthesis of PET polyester.展开更多
Direct melt/solid polycondensation of lactic acid(LA)was carried out to obtain high molecular weight poly(lactic acid)(PLA)by a process using various catalysts in the first-step melt polycondensation,and followed soli...Direct melt/solid polycondensation of lactic acid(LA)was carried out to obtain high molecular weight poly(lactic acid)(PLA)by a process using various catalysts in the first-step melt polycondensation,and followed solid polycondensation by using p-toulenesulfonic acid monohydrate(TSA)as the catalyst in the second step.Effects of various catalysts and reaction temperature on the molecular weight and crystallinity of resulting PLA polymers were examined.It was shown that SnCl_2·2H_2O/TSA,SnCl_2·2H_2O/succinic ...展开更多
Two aromatic co-polyamides were synthesized combining two diacid monomers containing bulky pendant groups, 5-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)isophthalic acid(DEAIA) and 5-tert-butylisophthalic ...Two aromatic co-polyamides were synthesized combining two diacid monomers containing bulky pendant groups, 5-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)isophthalic acid(DEAIA) and 5-tert-butylisophthalic acid(TERT), with 4,4′-(hexafluoroisopropylidene)dianiline(HFA) or 2,3,5,6-tetramethyl-1,4-phenylenediamine(Durene) by direct polycondensation. The structures of the obtained aromatic co-polyamides were confirmed by FTIR, Raman and 1 H-NMR. The co-copolyamide films, DHTH and DDTD, exhibited rms-roughness values between 0.94 and 1.60 nm, respectively. Moreover, they presented good thermal stability up to300 °C. Young's moduli of the co-polyamide films were between 4.1 and 4.3 GPa. X-ray diffraction results showed that the co-polyamide films were amorphous due to the incorporation of both bulky pendant groups, tert-butyl and dibenzobarrelene. The combination of bulky pendant groups provided intrinsically transparent co-polyamide films with a transmittance higher than 88% in the range of 400-780 nm.Due to these outstanding film and optical properties, they are suggested to be flexible substrates in applications for solar cell and other portable electronic devices.展开更多
Microencapsulation of neroline inside microcapsules having a polyurethane shell based onβ-cyclodextrin(β-CD)and hexane diisocyanate was performed by interfacial polycondensation.The polyol nature ofβ-CD caused tigh...Microencapsulation of neroline inside microcapsules having a polyurethane shell based onβ-cyclodextrin(β-CD)and hexane diisocyanate was performed by interfacial polycondensation.The polyol nature ofβ-CD caused tight crosslinking of microcapsules wall.Microcapsules of neroline were characterized for their chemical composition and structure of the polyurethane shell by FTIR spectroscopy,thermogravimetric analysis,optical and electron microscopy,light scattering and electrophoresis measurements.Core content and encapsulation yield were 15%and 60%,respectively.Spherical microcapsules of mean diameter 29μm were slightly cationic with an isoelectric point of 6.3.Neroline-loaded microcapsules were fixed on cotton fabric using an impregnation technique.The functionalized fabric showed improved resistance to washing cycles in comparison with previously reported diol-based microcapsules.Such microcapsules display great potential for the long-lasting release of fragrance in the framework of cosmetotextile.展开更多
The process of producing high viscosity polyester by transesterification polycondensation needs to adjust the operating conditions and equipment structure of pre-polycondensation kettle and final polycondensation kett...The process of producing high viscosity polyester by transesterification polycondensation needs to adjust the operating conditions and equipment structure of pre-polycondensation kettle and final polycondensation kettle to realize process intensification.In view of this,the fluid volume function method of computational fluid dynamics numerical simulation was used to investigate the film formation and surface renewal characteristics of horizontal polycondensation kettle under different operating conditions,including viscosity,rotating speed and liquid height.The results show that the viscosity and rotating speed were positively correlated with the film area and surface renewal in the pre-polycondensation stage.However,increasing the viscosity by several orders of magnitude in the final polycondensation kettle,the larger the film area and film thickness,but the overall surface renewal of the disk decreased.Therefore,a hexagonal hole disk is designed.By comparison,it is found that the film is more uniform,the surface update frequency is higher,and the power consumption can be reduced by more than 20%.展开更多
A non-aqueous suspension polycondensation method was proposed to proceed the reaction ofp-phenylenediamine and terephthaloyl chloride for the preparation of poly（p-phenylene terephthalamide） （PPTA）. The system was...A non-aqueous suspension polycondensation method was proposed to proceed the reaction ofp-phenylenediamine and terephthaloyl chloride for the preparation of poly（p-phenylene terephthalamide） （PPTA）. The system was operated with NMP-CaCI2 solution as the dispersed phase and inert liquid paraffin as the continuous phase. Each of NMP-CaCl2 solution microdroplet suspended in paraffin served as a microreactor where the polycondensation took place. According to the results of TGA, XRD, IR, SEM and EA, PPTA with good quality was obtained through this novel method, and a number of main factors influencing this process were investigated to determine the optimum condition for the preparation of PPTA. Besides, this two-phase polycondensation system brings many unique advantages compared to the conventional solution polycondensation method, including a sealed reaction environment keeping the reactants away from oxygen and water, easy removal of HCI to promote the reaction, well-controlled temperature and low viscosity which means less energy cost.展开更多
A non-isocyanate route for synthesizing thermoplastic polyurethanes with excellent thermal and mechanical properties was described. Melt transurethane polycondensation of 1,6-bis（hydroxyethyloxy carbonyl amino）hexan...A non-isocyanate route for synthesizing thermoplastic polyurethanes with excellent thermal and mechanical properties was described. Melt transurethane polycondensation of 1,6-bis（hydroxyethyloxy carbonyl amino）hexane with four poly（ethylene glycol）s （PEGs）, i.e. PEG400, PEG600, PEG1000, or PEG1500, was conducted at different molar ratios. A series of thermoplastic poly（ether urethane）s （TPEUs） with long PEG sequences were prepared. The TPEUs were characterized via gel permeation chromatography, FTIR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray scattering, and tensile tests. The TPEUs exhibit Tg between 12.4 ℃ and -40.4 ℃, Tm of up to 149.8 ℃, and initial decomposition temperature over 239.4 ℃. The tensile strength of the TPEUs reaches 38.39 MPa with a strain at break of 852.92%.展开更多
Poly（butylene terephthalate）-poly（tetramethylene glycol） （PBT-PTMG） copolymer is prepared with terephthalic acid （PTA） rather than its dimethyl ester （DMT） as starting material by a two-step melt polycondens...Poly（butylene terephthalate）-poly（tetramethylene glycol） （PBT-PTMG） copolymer is prepared with terephthalic acid （PTA） rather than its dimethyl ester （DMT） as starting material by a two-step melt polycondensation. This process includes the synthesis of PBT prepolymer from PTA with 1,4-butanediol （BDO） in the first step, followed by the synthesis of PBT-PTMG copolymer from PBT prepolymer with PTMG in the second step. The molecular weight, composition as well as thermal and mechanical properties of the products from the two-step melt polycondensation are compared with the properties of the PBT-PTMG from the traditional one-step melt polycondensation. When the PTMG content is low, there is only slight difference in molecular weight, composition, thermal and mechanical properties among PBT-PTMG copolymers obtained from these two methods. However, when the PTMG content is high, only the two-step strategy is able to give high molecular weight products, and the products have comparable thermal and mechanical properties with those from traditional one-step strategy using DMT as starting material.展开更多
A simple one-pot non-isocyanate route for synthesizing thermoplastic polyureas is presented. In situ urethanization was conducted from the ring-opening reaction of ethylene carbonate with poly(propylene glycol) bis(2-...A simple one-pot non-isocyanate route for synthesizing thermoplastic polyureas is presented. In situ urethanization was conducted from the ring-opening reaction of ethylene carbonate with poly(propylene glycol) bis(2-aminopropyl ether) and hexanediamine,m-xylylenediamine, or diethylene glycol bis(3-aminopropyl) ether at 100 °C for 6 h under normal pressure. Melt transurethane polycondensation was successively conducted at 170 °C under a reduced pressure of 399 Pa for different time periods. A series of nonisocyanate thermoplastic polyureas(NI-TPUreas) were prepared. The NI-TPUreas were characterized by gel permeation chromatography,FTIR, 1 H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, atomic force microscopy,and tensile test. NI-TPUreas exhibited Mn of up to 1.67 × 104 g/mol, initial decomposition temperature over 290 °C, and tensile strength of up to 32 MPa. Several crystallizable NI-TPUreas exhibited Tm exceeding 98 °C. NI-TPUreas with good thermal and mechanical properties were prepared through a green and simple one-pot non-isocyanate route.展开更多
A highly efficient and eco-friendly protocol for the synthesis of an alternating copolymer poly(7,7'-diazaisoindigo-alt-(E)-1,2- bis(3,4-difluorothien-2-yl)ethene)(PAIID-4FTVT) via direct arylation polycondensatio...A highly efficient and eco-friendly protocol for the synthesis of an alternating copolymer poly(7,7'-diazaisoindigo-alt-(E)-1,2- bis(3,4-difluorothien-2-yl)ethene)(PAIID-4FTVT) via direct arylation polycondensation (DArP) is presented. Through detailed study, we found that the inhibitory effect of 7,7'-diazaisoindigo on DArP stemmed from the coordination of N atom with catalyst can be overcome by using dimethylacetamide (DMAc) as the co-solvent. Thus, PAIID-4FTVT with number-average molecular weight (Mn)>100kDa was synthesized via DArP by optimizing the content of DMAc. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectroscopy revealed that PAIID-4FTVT was defect-free. Top gate and bottom contact (TG/BC) organic thin-film transistors (OTFTs) were fabricated to characterize the semiconducting properties of the polymers. PAIID-4FTVT displayed unipolar n-type characteristics with the electron mobility (μe) strongly dependent on Mn. The highest μe up to 0.25 cm^2·V^-1 s^-1 was achieved with the high molecular weight sample.展开更多
A diamine was synthesized by two successive reactions. Nucleophilic reaction of 4-hydroxybenzoic acid with terephthaloyl chloride yielded terephthaloyl bis（4-oxybenzoic） acid. Then reaction of this compound with 1,8...A diamine was synthesized by two successive reactions. Nucleophilic reaction of 4-hydroxybenzoic acid with terephthaloyl chloride yielded terephthaloyl bis（4-oxybenzoic） acid. Then reaction of this compound with 1,8-diamino-3,6- dioxaoctane via Yamazaki method resulted in preparation of diamine named terephthalic acid bis（4-{2-[2-（2-amino ethoxy）ethoxy]ethyl carbamoyl}phenyl） ester. After fully characterization it was used to prepare new polyimides through polycondensation with different dianhydrides using trimethylchlorosilane. Characterization of polymers was achieved by common methods and their physical properties including inherent viscosity, thermal behavior, thermal stability, crystallinity and solubility were studied. Prepared polyimides showed improved solubility and good thermal stability.展开更多
Because of its high purity and excellent orientation, mesophase pitch is a superior precursor for high-performance car-bon materials. However, the preparation of top-notch mesophase pitch faces challenges. Catalytic p...Because of its high purity and excellent orientation, mesophase pitch is a superior precursor for high-performance car-bon materials. However, the preparation of top-notch mesophase pitch faces challenges. Catalytic polycondensation at low temperat-ures is more favorable for synthesizing mesophase pitch, because it circumvents the high-temperature free radical reaction of other thermal polycondensation approaches. The reaction is gentle and can be easily controlled. It has the potential to significantly im-prove the yield of mesophase pitch and easily introduce naphthenic characteristics into the molecules, catalytic polycondensation is therefore a preferred method of synthesizing highly spinnable mesophase pitch. This review provides a synopsis of the selective pre-treatment of the raw materials to prepare different mesophase pitches, and explains the reaction mechanism and associated research advances for different catalytic systems in recent years. Finally, how to manufacture high-quality mesophase pitch by using a cata-lyst-promoter system is summarized and proposed, which may provide a theoretical basis for the future design of high-quality pitch molecules.展开更多
文摘Reducing the amount of aluminum chloride needed for the catalytic preparation of high quality mesophase and carbon materials is important and we have found that using terephthalic acid(PTA)as a co-catalyst serves this purpose.By adding 3%(mass fraction)AlCl_(3)and 0.9%(mass fraction)PTA to the coal tar pitch,approximately 90%mesophase was synthesized.The product(M-3-0.9)had a high stacking order(L_(c)=3.1 nm,n=10.14)and aromaticity(0.942).By adding PTA,a larger anisotropy content was produced using a smaller amount of AlCl_(3).The PTA participated in the polycondensation reaction through its own benzene ring structure to increase the catalytic activity.However,when its content was higher than 1.5%,the number of oxygen-containing groups in the product increased which was unfavorable for the aromatic lamellar stacking and gave rise to more isotropic structures.The work opens up a new way to prepare mesophase by a catalytic method.
基金Funded by the Program(BG2021)of High-end Foreign Experts of The State Administration of Foreign Experts Affairs(SAFEA)the Young Talent Project of Hubei Provincial Department of Education,China(No.Q20201108)。
文摘High molecular weight poly(1,4-butylene 2,5-furandicarboxylate-co-isosorbide 2,5-furandicarboxylate)copolyesters(PBSIF-x)were synthesized via melt-polycondensation of 2,5-furandicarboxylic acid(FDCA),with varying ratios of isosorbide(ISB)and 1,4-butylene glycol(BDO)catalyzed by antimony trioxide(Sb_(2)O_(3)).The PBSIF-x structures were investigated using FTIR and~1H NMR,while the GPC analysis exhibited the copolyesters molecular weights with number average molecular mass(M_n)in the range of 11079-15153 g/mol.The DSC results show that PBSIF-x copolyesters have a single glass-transition temperature(T_(g))(77.45-110.96℃),increasing with the increase in ISB content,while TGA analysis demonstrates excellent thermal stability up to 320℃.From the thermal result,properties of PBSIF-x copolyesters are found to be within the interval of their parent homologues poly(butylene 2,5-furandicarboxylate)(PBF)and poly(isosorbide 2,5-furandicarboxylate)(PIF),which confirms the aromatic/aliphatic blending within the polymer matrix for enhanced polymer stability and performance.
基金financially supported by the Russian Science Foundation(No.23-43-00060)。
文摘An efficient,simple,and convenient method for Suzuki polycondensation using a diaminocarbene palladium(Ⅱ)catalyst under aerobic conditions was developed.Reactions between aromatic diboronic acid bis(pinacol)ester and different aromatic dibromides,both with electrondonating and electron-withdrawing fragments in the structure,were carried out.Various reaction conditions,such as the effect of catalyst concentration and solvent,were investigated.The molecular weight characteristics,photo-and electroluminescence properties of the synthesized polymers were studied.
基金financially supported by the National Natural Science Foundation of China(No.51473031)the Shanghai International S&T Cooperation Fund(No.16160731302)
文摘This work described the preparation of easily colored meta-aramid(PMIA) copolymers from m-phenylenediamine(MPD),isophthaloyl dichloride(IPC), and 3,4′-oxydianiline(3,4′-ODA) via solution polycondensation in N,N-dimethylacetamide(DMAc). The novel co-PMIAs were obtained in relatively high inherent viscosities ranging from 1.32 dL/g to 2.53 dL/g, which could be easily cast into flexible films with high transparence or spun into fibers. All the newly synthesized copolymers possessed excellent thermal stabilities even better than that of commercial PMIA, with 5% weight loss temperatures higher than 430 °C in nitrogen measured by TGA and glass transition temperature of 267–277 °C measured by DSC. The cast films exhibited good mechanical properties with a tensile strength up to107 MPa and a tensile modulus up to 2.2 GPa. The resultant PMIAs also showed good solubility and better dye ability for cationic dyes.
基金supported by the National Key Projects for Fundamental Research and Development of China(2016YFB0600903)the National Natural Science Foundation of China(91434107,21506226,21476245)the Key Research Program of Frontier Sciences of Chinese Academy of Sciences(QYZDY-SSW-JSC011)~~
文摘A series of quaternary ammonium ionic liquids(ILs)were synthesized and employed as catalysts for the production of poly(isosorbide carbonate)(PIC)from diphenyl carbonate and isosorbide via a melt polycondensation process.The relationship between the anions of the ILs and the catalytic activities was investigated,and the readily‐prepared IL tetraethylammonium imidazolate(TEAI)was found to exhibit the highest catalytic activity.After optimizing the reaction conditions,a PIC with a weight‐average molecular weight(Mw)of25600g/mol was obtained,in conjunction with an isosorbide conversion of92%.As a means of modifying the molecular flexibility and thermal properties of the PIC,poly(aliphatic diol‐co‐isosorbide carbonate)s(PAIC)s were successfully synthesized,again using TEAI,and polymers with Mw values ranging from29000to112000g/mol were obtained.13C NMR analyses determined that the PAIC specimens had random microstructures,while differential scanning calorimetry demonstrated that each of the PAICs were amorphous and had glass transition temperatures ranging from50to115°C.Thermogravimetric analyses found Td‐5%values ranging from316to332°C for these polymers.Based on these data,it is evident that the incorporation of linear or cyclohexane‐based diol repeating units changed the thermal properties of the PIC.
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Polyurea microcapsules about 2.5 μm in diameter containing phase change material for thermal energy storage application were synthesized and characterized by interfacial polycondensation method with toluene-2,4-diisocyanate and ethylenediamine as monomers in an emulsion system. Hexadecane was used as a phase change material and OP, which is nonionic surfactant, and used as an emulsifier. The chemical structure and thermal behavior of the microcapsules were investigated by FTIR and thermal analysis respectively. The results show encapsulated hexadecane has a good potential as a solar energy storage material.
基金supported by the Forestry Public Special Scientific Research (No. 201004057)
文摘The increase in the residue content resulting from polycondensation would be adverse to the utilization of lignocellulose and to the quality of products obtained from liquefied lignocellulosic material.The yield of the residue formed from liquefaction and the mechanism of polycondensation were reported mainly by Lin,Yamada and Kobayashi.The major products of cellulosic liquefaction are levulinic acid and hydroxymethylfurfural（HMF） derivatives under polyhydric alcohols and phenolated compounds under phenols.The cleavage of the β-O-4 bonds is the major reaction pathway of lignin liquefaction under various liquefying reagents regardless of whether they contain acid catalysts or not.The break up compounds by decomposition are polymerized to substances with high molecular weight by polycondensation in lignocellulosic liquefaction.The molecular weight of condensed residues increases almost linearly as a function of liquefaction time at the later stage of lignocellulosic liquefaction.The longer the time required,the greater the content of new residue generated by polycondensation during the entire process of liquefaction.We conclude that the condensed residues may stem from the interaction of degraded lignin and cellulose components in wood or from the products of two major components reacting with liquefying reagents.
文摘Ethylene glycol aluminum was prepared efficiently and characterized by FT-IR and NMR.It exhibited higher catalytic activity and had profitable effect than titanium glycolate and ethylene glycol antimony for the synthesis of poly(ethylene terephthalate)(PET).It was only used as polycondensation catalyst because it was sensitive to water.For this catalyst,the degree of esterification of the theoretical amount of water was produced up to 95%at 260℃,while the intrinsic viscosity and content of terminal carboxyl groups of the corresponding PET polyester,polymerized at 280℃,70 Pa for 39 min,was 0.87 dL/g and 23.0μmol/g,respectively.Ethylene glycol aluminum was a promising catalyst for the synthesis of PET polyester.
基金the HMPURT(No.2006KYCX009)the National Natural Science Foundation of Henan(No.200510465008)Henan Innovation Project(No.0523021300)
文摘Direct melt/solid polycondensation of lactic acid(LA)was carried out to obtain high molecular weight poly(lactic acid)(PLA)by a process using various catalysts in the first-step melt polycondensation,and followed solid polycondensation by using p-toulenesulfonic acid monohydrate(TSA)as the catalyst in the second step.Effects of various catalysts and reaction temperature on the molecular weight and crystallinity of resulting PLA polymers were examined.It was shown that SnCl_2·2H_2O/TSA,SnCl_2·2H_2O/succinic ...
基金the financial support from CONACYT-México(No.248378)CONACYT-México for the fellowship 427467partially supported by the project "Fortalecimiento e internacionalización del doctorado en ciencias(Materiales Poliméricos)del CICY" FOMIX YUC 2014-C17-247046
文摘Two aromatic co-polyamides were synthesized combining two diacid monomers containing bulky pendant groups, 5-(9,10-dihydro-9,10-ethanoanthracene-11,12-dicarboximido)isophthalic acid(DEAIA) and 5-tert-butylisophthalic acid(TERT), with 4,4′-(hexafluoroisopropylidene)dianiline(HFA) or 2,3,5,6-tetramethyl-1,4-phenylenediamine(Durene) by direct polycondensation. The structures of the obtained aromatic co-polyamides were confirmed by FTIR, Raman and 1 H-NMR. The co-copolyamide films, DHTH and DDTD, exhibited rms-roughness values between 0.94 and 1.60 nm, respectively. Moreover, they presented good thermal stability up to300 °C. Young's moduli of the co-polyamide films were between 4.1 and 4.3 GPa. X-ray diffraction results showed that the co-polyamide films were amorphous due to the incorporation of both bulky pendant groups, tert-butyl and dibenzobarrelene. The combination of bulky pendant groups provided intrinsically transparent co-polyamide films with a transmittance higher than 88% in the range of 400-780 nm.Due to these outstanding film and optical properties, they are suggested to be flexible substrates in applications for solar cell and other portable electronic devices.
基金by the“Ministry of Higher Education and Scientific Research”of Tunisia,Laboratory of Advanced Materials and Interfaces(LAMI,LR-11-S-55)。
文摘Microencapsulation of neroline inside microcapsules having a polyurethane shell based onβ-cyclodextrin(β-CD)and hexane diisocyanate was performed by interfacial polycondensation.The polyol nature ofβ-CD caused tight crosslinking of microcapsules wall.Microcapsules of neroline were characterized for their chemical composition and structure of the polyurethane shell by FTIR spectroscopy,thermogravimetric analysis,optical and electron microscopy,light scattering and electrophoresis measurements.Core content and encapsulation yield were 15%and 60%,respectively.Spherical microcapsules of mean diameter 29μm were slightly cationic with an isoelectric point of 6.3.Neroline-loaded microcapsules were fixed on cotton fabric using an impregnation technique.The functionalized fabric showed improved resistance to washing cycles in comparison with previously reported diol-based microcapsules.Such microcapsules display great potential for the long-lasting release of fragrance in the framework of cosmetotextile.
基金the financial support of the National Key Research and Development Program of China(2020YFA0710202,2018YFC0808805)。
文摘The process of producing high viscosity polyester by transesterification polycondensation needs to adjust the operating conditions and equipment structure of pre-polycondensation kettle and final polycondensation kettle to realize process intensification.In view of this,the fluid volume function method of computational fluid dynamics numerical simulation was used to investigate the film formation and surface renewal characteristics of horizontal polycondensation kettle under different operating conditions,including viscosity,rotating speed and liquid height.The results show that the viscosity and rotating speed were positively correlated with the film area and surface renewal in the pre-polycondensation stage.However,increasing the viscosity by several orders of magnitude in the final polycondensation kettle,the larger the film area and film thickness,but the overall surface renewal of the disk decreased.Therefore,a hexagonal hole disk is designed.By comparison,it is found that the film is more uniform,the surface update frequency is higher,and the power consumption can be reduced by more than 20%.
基金financially supported by the National Natural Science Foundation of China(Nos.U1463208 and 91334201)
文摘A non-aqueous suspension polycondensation method was proposed to proceed the reaction ofp-phenylenediamine and terephthaloyl chloride for the preparation of poly（p-phenylene terephthalamide） （PPTA）. The system was operated with NMP-CaCI2 solution as the dispersed phase and inert liquid paraffin as the continuous phase. Each of NMP-CaCl2 solution microdroplet suspended in paraffin served as a microreactor where the polycondensation took place. According to the results of TGA, XRD, IR, SEM and EA, PPTA with good quality was obtained through this novel method, and a number of main factors influencing this process were investigated to determine the optimum condition for the preparation of PPTA. Besides, this two-phase polycondensation system brings many unique advantages compared to the conventional solution polycondensation method, including a sealed reaction environment keeping the reactants away from oxygen and water, easy removal of HCI to promote the reaction, well-controlled temperature and low viscosity which means less energy cost.
基金financially supported by the National Natural Science Foundation of China(Nos.21244006 and 50873013)
文摘A non-isocyanate route for synthesizing thermoplastic polyurethanes with excellent thermal and mechanical properties was described. Melt transurethane polycondensation of 1,6-bis（hydroxyethyloxy carbonyl amino）hexane with four poly（ethylene glycol）s （PEGs）, i.e. PEG400, PEG600, PEG1000, or PEG1500, was conducted at different molar ratios. A series of thermoplastic poly（ether urethane）s （TPEUs） with long PEG sequences were prepared. The TPEUs were characterized via gel permeation chromatography, FTIR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray scattering, and tensile tests. The TPEUs exhibit Tg between 12.4 ℃ and -40.4 ℃, Tm of up to 149.8 ℃, and initial decomposition temperature over 239.4 ℃. The tensile strength of the TPEUs reaches 38.39 MPa with a strain at break of 852.92%.
基金financially supported by the Key Research Program of the Chinese Academy of Sciences(No.KGZD-EW-606-16)Ningbo Key Lab of Polymer Materials(No.2010A22001)Ningbo Natural Science Foundation(Nos.2013A610025,2013A610023 and 2014A610135)
文摘Poly（butylene terephthalate）-poly（tetramethylene glycol） （PBT-PTMG） copolymer is prepared with terephthalic acid （PTA） rather than its dimethyl ester （DMT） as starting material by a two-step melt polycondensation. This process includes the synthesis of PBT prepolymer from PTA with 1,4-butanediol （BDO） in the first step, followed by the synthesis of PBT-PTMG copolymer from PBT prepolymer with PTMG in the second step. The molecular weight, composition as well as thermal and mechanical properties of the products from the two-step melt polycondensation are compared with the properties of the PBT-PTMG from the traditional one-step melt polycondensation. When the PTMG content is low, there is only slight difference in molecular weight, composition, thermal and mechanical properties among PBT-PTMG copolymers obtained from these two methods. However, when the PTMG content is high, only the two-step strategy is able to give high molecular weight products, and the products have comparable thermal and mechanical properties with those from traditional one-step strategy using DMT as starting material.
基金financially supported by the National Natural Science Foundation of China (No. 21244006)Beijing Natural Science Foundation (No. 2182056)
文摘A simple one-pot non-isocyanate route for synthesizing thermoplastic polyureas is presented. In situ urethanization was conducted from the ring-opening reaction of ethylene carbonate with poly(propylene glycol) bis(2-aminopropyl ether) and hexanediamine,m-xylylenediamine, or diethylene glycol bis(3-aminopropyl) ether at 100 °C for 6 h under normal pressure. Melt transurethane polycondensation was successively conducted at 170 °C under a reduced pressure of 399 Pa for different time periods. A series of nonisocyanate thermoplastic polyureas(NI-TPUreas) were prepared. The NI-TPUreas were characterized by gel permeation chromatography,FTIR, 1 H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, atomic force microscopy,and tensile test. NI-TPUreas exhibited Mn of up to 1.67 × 104 g/mol, initial decomposition temperature over 290 °C, and tensile strength of up to 32 MPa. Several crystallizable NI-TPUreas exhibited Tm exceeding 98 °C. NI-TPUreas with good thermal and mechanical properties were prepared through a green and simple one-pot non-isocyanate route.
基金financially supported by the National Key R&D Program of “Strategic Advanced Electronic Materials” (No. 2016YFB0401101) of the Chinese Ministry of Science and Technologythe National Natural Science Foundation of China (No. 51333006)
文摘A highly efficient and eco-friendly protocol for the synthesis of an alternating copolymer poly(7,7'-diazaisoindigo-alt-(E)-1,2- bis(3,4-difluorothien-2-yl)ethene)(PAIID-4FTVT) via direct arylation polycondensation (DArP) is presented. Through detailed study, we found that the inhibitory effect of 7,7'-diazaisoindigo on DArP stemmed from the coordination of N atom with catalyst can be overcome by using dimethylacetamide (DMAc) as the co-solvent. Thus, PAIID-4FTVT with number-average molecular weight (Mn)>100kDa was synthesized via DArP by optimizing the content of DMAc. Matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectroscopy revealed that PAIID-4FTVT was defect-free. Top gate and bottom contact (TG/BC) organic thin-film transistors (OTFTs) were fabricated to characterize the semiconducting properties of the polymers. PAIID-4FTVT displayed unipolar n-type characteristics with the electron mobility (μe) strongly dependent on Mn. The highest μe up to 0.25 cm^2·V^-1 s^-1 was achieved with the high molecular weight sample.
文摘A diamine was synthesized by two successive reactions. Nucleophilic reaction of 4-hydroxybenzoic acid with terephthaloyl chloride yielded terephthaloyl bis（4-oxybenzoic） acid. Then reaction of this compound with 1,8-diamino-3,6- dioxaoctane via Yamazaki method resulted in preparation of diamine named terephthalic acid bis（4-{2-[2-（2-amino ethoxy）ethoxy]ethyl carbamoyl}phenyl） ester. After fully characterization it was used to prepare new polyimides through polycondensation with different dianhydrides using trimethylchlorosilane. Characterization of polymers was achieved by common methods and their physical properties including inherent viscosity, thermal behavior, thermal stability, crystallinity and solubility were studied. Prepared polyimides showed improved solubility and good thermal stability.
文摘Because of its high purity and excellent orientation, mesophase pitch is a superior precursor for high-performance car-bon materials. However, the preparation of top-notch mesophase pitch faces challenges. Catalytic polycondensation at low temperat-ures is more favorable for synthesizing mesophase pitch, because it circumvents the high-temperature free radical reaction of other thermal polycondensation approaches. The reaction is gentle and can be easily controlled. It has the potential to significantly im-prove the yield of mesophase pitch and easily introduce naphthenic characteristics into the molecules, catalytic polycondensation is therefore a preferred method of synthesizing highly spinnable mesophase pitch. This review provides a synopsis of the selective pre-treatment of the raw materials to prepare different mesophase pitches, and explains the reaction mechanism and associated research advances for different catalytic systems in recent years. Finally, how to manufacture high-quality mesophase pitch by using a cata-lyst-promoter system is summarized and proposed, which may provide a theoretical basis for the future design of high-quality pitch molecules.
