The gas barrier film formation technique using simultaneous photo-irradiation and heat-treatment has been researched on alicyclic polyimide film coated with a polysilazane solution. A fine SiO2 thin film on polyimide ...The gas barrier film formation technique using simultaneous photo-irradiation and heat-treatment has been researched on alicyclic polyimide film coated with a polysilazane solution. A fine SiO2 thin film on polyimide film was formed at low temperatures, which greatly improved the substrate’s gas barrier characteristics by this technique. The values of gas barrier characteristics depended on the substrate temperature at the time of photo-irradiation. For photo-irradiated thin film heat-treated to 150°C, the water vapor transmission rate and oxygen transmission rate fell below the equipment measurement limit of 0.02 g/m2/day and 0.02 cm3/m2/day, respectively. This polyimide film with a gas-barrier film coating has good transmittance in the region of visible light, heat resistance, and flexibility.展开更多
Organo-soluble alicyclic polyimides (ALPIs) were synthesized from an alicyclic dianhydride, 1,8-dimethyl-bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (DMEA) and several multialkyl-substituted 4,4'-d...Organo-soluble alicyclic polyimides (ALPIs) were synthesized from an alicyclic dianhydride, 1,8-dimethyl-bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (DMEA) and several multialkyl-substituted 4,4'-diaminodiphenylmethane compounds, including 3,3'-dimethyl-4,4'-diaminodiphenyt methane (DMDA), 3,31,5,5'-tetramethyl-4,4'-diaminodiphenyl methane (TMDA) and 3,3',5,5'-tetraethyl-4,4'-diaminodiphenylmethane (TEDA). For comparison, the aromatic polyimides (ARPIs) were synthesized from the aromatic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and the same diamines. The ALPIs exhibited better solubility and transparency, but worse thermal stabilities and mechanical properties than those of the ARPIs. And the ALPIs could be dissolved in common organic solvents, such as N-methyl-2-pyrrolidinone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), chloroform, tetrahydrofuran, m-cresol and so on. The ALPI films had an UV-Vis cut-off at 320 nm and a transmittance of higher than 80% in the visible region. In addition, the ALPIs showed thermal decomposition temperatures (T-d) of about 450degreesC, which was nearly 100degreesC lower than that of the ARPIs.展开更多
In this study,nanosheet g-C_(3)N_(4)-H_(2) was prepared by thermal exfoliation of bulk g-C_(3)N_(4) under hydrogen.A series of Ru/g-C_(3)N_(4)-H_(2) catalysts with Ru species supported on the nanosheet g-C_(3)N_(4)-H_...In this study,nanosheet g-C_(3)N_(4)-H_(2) was prepared by thermal exfoliation of bulk g-C_(3)N_(4) under hydrogen.A series of Ru/g-C_(3)N_(4)-H_(2) catalysts with Ru species supported on the nanosheet g-C_(3)N_(4)-H_(2) were synthesized via ultrasonic assisted impregnation-deposition method.Ultrafine Ru nanoparticles(<2 nm)were highly dispersed on nanosheet g-C_(3)N_(4)-H_(2).Strong interaction due to Ru-Nx coordination facilitated the uniform distribution of Ru species.Meanwhile,the involvement of surface basicity derived from abundant nitrogen sites was favourable for enhancing the selective hydrogenation performance of bi-benzene ring,i.e.,almost complete 4,40-diaminodiphenylmethane(MDA)conversion and>99%4,40-diaminodicyclohexylmethane selectivity,corresponding to a reaction activity of 35.7 mol_(MDA) mol_(Ru)^(-1) h^(-1).Moreover,the reaction activity of catalyst in the fifth run was 36.5 mol_(MDA) mol_(Ru)^(-1) h^(-1),which was comparable with that of the fresh one.The computational results showed that g-C_(3)N_(4) as support was favorable for adsorption and dissociation of H_(2) molecules.Moreover,the substrate scope can be successfully expanded to a variety of other aromatic diamines.Therefore,this work provides an efficient and green catalyst system for selective hydrogenation of aromatic diamines.展开更多
The kinetics of charge transfer complex(CTC) of 2,3,5,6 tetramethoxyl 1,4 benzoquinone(TMOQ) with two alicyclic N donors,piperidine(PD) and morpholine(ML), in methanol, has been investigated by ultraviolet visible spe...The kinetics of charge transfer complex(CTC) of 2,3,5,6 tetramethoxyl 1,4 benzoquinone(TMOQ) with two alicyclic N donors,piperidine(PD) and morpholine(ML), in methanol, has been investigated by ultraviolet visible spectroscopy. The transformation leads to the formation of substitution products in solution, which have been isolated and characterized as 2,5 diamino 3,6 dimethoxyl 1,4 benzoquinones by 1H NMR, MS, and elemental analysis. The kinetic results of the formation of products indicate that the rate is first order both with the acceptor and the donor. A mechanism of interaction between TMOQ and PD or ML is discussed.展开更多
The electrical, physical, mechanical and thermal properties of fluorine-containing alicyclic polyimides have been investigated. It was shown that the minimum value of the dielectric constant 1.91 at room temperature a...The electrical, physical, mechanical and thermal properties of fluorine-containing alicyclic polyimides have been investigated. It was shown that the minimum value of the dielectric constant 1.91 at room temperature and 1 kHz frequency was achieved for polymers containing only one fluorine atom in the structure. The dielectric loss tangent of new polymers was （I -4）~ 103. Electro-physical parameters were stable during polymer heating up to 300 ~C, and at the frequency from 1 to 20 kHz. Resistivity by heating in the air up to 320-380 ~C has been investigated depending on the polyimides structure. The coefficient of moisture absorption for the fluorine-containing polyimide based on dianhydride with 4,4＇-oxydianiline was determined at 50% humidity and 25 ℃. It was around 0.6, but after immersion in the water for 24 and 48 h was 0.8% and 1.2%, respectively. Manufactured films had tensile strength to 160-170 MPa, and elongation up to 55%.展开更多
Results of researches on study of the kinetics and isomerization mechanism of the alkyladamantanes in the presence of the heterogeneous catalysts of the acid type are considered as detection and experimental proof of ...Results of researches on study of the kinetics and isomerization mechanism of the alkyladamantanes in the presence of the heterogeneous catalysts of the acid type are considered as detection and experimental proof of a new intramolecular rearrangement of the carbcations bridged alicyclic hydrocarbons--2,4-moving of the methyl groups （β-methyl shift）. The proof of realization of such rearrangement is direct and primary formation 1,4-dimethyladamantane from 1,2-dimethyladamatane, passing a formation stage of the thermodynamic much stable 1,3-dimethyladamantane; direct formation 1,3,6-trimethyladamantane from 1,3,4-trimethyladamantane, excepting a formation stage 1,3.5-trimethyladamantane, and also other isomers which formation is impossible to explain by means of known 1,2-methyl shift （a-methyl shift）.展开更多
文摘The gas barrier film formation technique using simultaneous photo-irradiation and heat-treatment has been researched on alicyclic polyimide film coated with a polysilazane solution. A fine SiO2 thin film on polyimide film was formed at low temperatures, which greatly improved the substrate’s gas barrier characteristics by this technique. The values of gas barrier characteristics depended on the substrate temperature at the time of photo-irradiation. For photo-irradiated thin film heat-treated to 150°C, the water vapor transmission rate and oxygen transmission rate fell below the equipment measurement limit of 0.02 g/m2/day and 0.02 cm3/m2/day, respectively. This polyimide film with a gas-barrier film coating has good transmittance in the region of visible light, heat resistance, and flexibility.
基金This work was supported by the National Natural Science Foundation of China under the Grant for Distinguished YoungScholars (No. 59925310).
文摘Organo-soluble alicyclic polyimides (ALPIs) were synthesized from an alicyclic dianhydride, 1,8-dimethyl-bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydride (DMEA) and several multialkyl-substituted 4,4'-diaminodiphenylmethane compounds, including 3,3'-dimethyl-4,4'-diaminodiphenyt methane (DMDA), 3,31,5,5'-tetramethyl-4,4'-diaminodiphenyl methane (TMDA) and 3,3',5,5'-tetraethyl-4,4'-diaminodiphenylmethane (TEDA). For comparison, the aromatic polyimides (ARPIs) were synthesized from the aromatic dianhydride, 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and the same diamines. The ALPIs exhibited better solubility and transparency, but worse thermal stabilities and mechanical properties than those of the ARPIs. And the ALPIs could be dissolved in common organic solvents, such as N-methyl-2-pyrrolidinone (NMP), N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), chloroform, tetrahydrofuran, m-cresol and so on. The ALPI films had an UV-Vis cut-off at 320 nm and a transmittance of higher than 80% in the visible region. In addition, the ALPIs showed thermal decomposition temperatures (T-d) of about 450degreesC, which was nearly 100degreesC lower than that of the ARPIs.
基金financially supported by the National Nature Science Foundation of China(21576272)“Transformational Technologies for Clean Energy and Demonstration”,Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDA 21030600)Science and Technology Service Network Initiative,Chinese Academy of Sciences(KFJ-STS-QYZD-138).
文摘In this study,nanosheet g-C_(3)N_(4)-H_(2) was prepared by thermal exfoliation of bulk g-C_(3)N_(4) under hydrogen.A series of Ru/g-C_(3)N_(4)-H_(2) catalysts with Ru species supported on the nanosheet g-C_(3)N_(4)-H_(2) were synthesized via ultrasonic assisted impregnation-deposition method.Ultrafine Ru nanoparticles(<2 nm)were highly dispersed on nanosheet g-C_(3)N_(4)-H_(2).Strong interaction due to Ru-Nx coordination facilitated the uniform distribution of Ru species.Meanwhile,the involvement of surface basicity derived from abundant nitrogen sites was favourable for enhancing the selective hydrogenation performance of bi-benzene ring,i.e.,almost complete 4,40-diaminodiphenylmethane(MDA)conversion and>99%4,40-diaminodicyclohexylmethane selectivity,corresponding to a reaction activity of 35.7 mol_(MDA) mol_(Ru)^(-1) h^(-1).Moreover,the reaction activity of catalyst in the fifth run was 36.5 mol_(MDA) mol_(Ru)^(-1) h^(-1),which was comparable with that of the fresh one.The computational results showed that g-C_(3)N_(4) as support was favorable for adsorption and dissociation of H_(2) molecules.Moreover,the substrate scope can be successfully expanded to a variety of other aromatic diamines.Therefore,this work provides an efficient and green catalyst system for selective hydrogenation of aromatic diamines.
文摘The kinetics of charge transfer complex(CTC) of 2,3,5,6 tetramethoxyl 1,4 benzoquinone(TMOQ) with two alicyclic N donors,piperidine(PD) and morpholine(ML), in methanol, has been investigated by ultraviolet visible spectroscopy. The transformation leads to the formation of substitution products in solution, which have been isolated and characterized as 2,5 diamino 3,6 dimethoxyl 1,4 benzoquinones by 1H NMR, MS, and elemental analysis. The kinetic results of the formation of products indicate that the rate is first order both with the acceptor and the donor. A mechanism of interaction between TMOQ and PD or ML is discussed.
文摘The electrical, physical, mechanical and thermal properties of fluorine-containing alicyclic polyimides have been investigated. It was shown that the minimum value of the dielectric constant 1.91 at room temperature and 1 kHz frequency was achieved for polymers containing only one fluorine atom in the structure. The dielectric loss tangent of new polymers was （I -4）~ 103. Electro-physical parameters were stable during polymer heating up to 300 ~C, and at the frequency from 1 to 20 kHz. Resistivity by heating in the air up to 320-380 ~C has been investigated depending on the polyimides structure. The coefficient of moisture absorption for the fluorine-containing polyimide based on dianhydride with 4,4＇-oxydianiline was determined at 50% humidity and 25 ℃. It was around 0.6, but after immersion in the water for 24 and 48 h was 0.8% and 1.2%, respectively. Manufactured films had tensile strength to 160-170 MPa, and elongation up to 55%.
文摘Results of researches on study of the kinetics and isomerization mechanism of the alkyladamantanes in the presence of the heterogeneous catalysts of the acid type are considered as detection and experimental proof of a new intramolecular rearrangement of the carbcations bridged alicyclic hydrocarbons--2,4-moving of the methyl groups （β-methyl shift）. The proof of realization of such rearrangement is direct and primary formation 1,4-dimethyladamantane from 1,2-dimethyladamatane, passing a formation stage of the thermodynamic much stable 1,3-dimethyladamantane; direct formation 1,3,6-trimethyladamantane from 1,3,4-trimethyladamantane, excepting a formation stage 1,3.5-trimethyladamantane, and also other isomers which formation is impossible to explain by means of known 1,2-methyl shift （a-methyl shift）.
