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1993 Volume 11 Issue 2
1993, 11(2): 97-102
Abstract:
Several silica-supported poly-γ-aminopropylsiloxane-monometal and bimetal complexes (Si-NH2-M,M = Cu or Co ; Si-NH2-Cu-M', M' =Co, Sn, Mn, Ni or Fe) have been prepared. Their catalytic properties for oxidative ethoxycarbonylation of aniline to ethyl phenylcarbamate have been investigated.The catalytic reaction was carried out under relatively mild conditions. The catalyst Si-NH2-Cu-CO had high activity and selectivity, and the turn-over number (molar of aniline converted/molar of metal in Si-NH2-Cu-CO added) could amount to 450 under the conditions:150℃,4 MPa (CO/O2=3) and 40 hours.The results of XPS and IR indicated that the coordination bonds were formed between nitrogen and metals in Si—NH2—Cu,Si—NH2—Co and Si—NH2—Cu—Co,and the coordination pattern was not single.In the oxidative ethoxycarbonylation of aniline to ethyl phenylcarbamate,the catalytic property of Si—NH2—Cu—Co bimetallic complex was better than Si—NH2—Cu or Si—NH2—Co monometallic complex.This indicated that there was synergistic action between different metals in the bimetallic complex.
Several silica-supported poly-γ-aminopropylsiloxane-monometal and bimetal complexes (Si-NH2-M,M = Cu or Co ; Si-NH2-Cu-M', M' =Co, Sn, Mn, Ni or Fe) have been prepared. Their catalytic properties for oxidative ethoxycarbonylation of aniline to ethyl phenylcarbamate have been investigated.The catalytic reaction was carried out under relatively mild conditions. The catalyst Si-NH2-Cu-CO had high activity and selectivity, and the turn-over number (molar of aniline converted/molar of metal in Si-NH2-Cu-CO added) could amount to 450 under the conditions:150℃,4 MPa (CO/O2=3) and 40 hours.The results of XPS and IR indicated that the coordination bonds were formed between nitrogen and metals in Si—NH2—Cu,Si—NH2—Co and Si—NH2—Cu—Co,and the coordination pattern was not single.In the oxidative ethoxycarbonylation of aniline to ethyl phenylcarbamate,the catalytic property of Si—NH2—Cu—Co bimetallic complex was better than Si—NH2—Cu or Si—NH2—Co monometallic complex.This indicated that there was synergistic action between different metals in the bimetallic complex.
1993, 11(2): 103-108
Abstract:
The cobalt and ruthenium bimetallic complex of poly-γ-amino-propylsiloxane( abbr. as Si-CH2-Co-Ru) was prepared, and it was found that it can catalyze the hydroformylation of cyclobexene effectively with the conversion amounting to over 90%. Cyclohexanecarboxaldehyde was first formed in the hydroformylation, and then further hydrogenated to form cylcohexanemethanol. The coversion was affected obviously by the Co/Ru ratio.When Co/Ru molar ratio was 100-150, i.e. in the very low content of noble metal Ru, the catalytic activity of Si-NH2-Co-Ru was also very high.The product composition was affected by CO/H2 ratio in the reaction gas.Aldehyde can be got high selectively by controlling CO/H2 ratio.Compared with other catalyst system,the Si-NH2-Co-Ru catalyst has higher catalytic activity and efficiency with very low Ru/Co ratio.The total turnover number was more than 28,800(based on the amount of rethenium used).
The cobalt and ruthenium bimetallic complex of poly-γ-amino-propylsiloxane( abbr. as Si-CH2-Co-Ru) was prepared, and it was found that it can catalyze the hydroformylation of cyclobexene effectively with the conversion amounting to over 90%. Cyclohexanecarboxaldehyde was first formed in the hydroformylation, and then further hydrogenated to form cylcohexanemethanol. The coversion was affected obviously by the Co/Ru ratio.When Co/Ru molar ratio was 100-150, i.e. in the very low content of noble metal Ru, the catalytic activity of Si-NH2-Co-Ru was also very high.The product composition was affected by CO/H2 ratio in the reaction gas.Aldehyde can be got high selectively by controlling CO/H2 ratio.Compared with other catalyst system,the Si-NH2-Co-Ru catalyst has higher catalytic activity and efficiency with very low Ru/Co ratio.The total turnover number was more than 28,800(based on the amount of rethenium used).
1993, 11(2): 109-114
Abstract:
A thermotropic liquid crystal copolyester resin based on p-hydroxybenzoic acid, 2, 6-naphthoic acid, hydroxyquinone and PET was synthesized by melt condensation and studied. The results based on DSC and X-ray diffraction indicated that there were a rapid and a slow crystallization processes for the copolyester at certain conditions. A critical temperature was suggested, below which the slow crystallization could hardly happen. Above the critical temperature the extent of the slow crystallization process depended not only on annealing temperature but also on the annealing time.A fine crystal structure with high melting point and narrow diffraction peak was formed under favorable conditions.
A thermotropic liquid crystal copolyester resin based on p-hydroxybenzoic acid, 2, 6-naphthoic acid, hydroxyquinone and PET was synthesized by melt condensation and studied. The results based on DSC and X-ray diffraction indicated that there were a rapid and a slow crystallization processes for the copolyester at certain conditions. A critical temperature was suggested, below which the slow crystallization could hardly happen. Above the critical temperature the extent of the slow crystallization process depended not only on annealing temperature but also on the annealing time.A fine crystal structure with high melting point and narrow diffraction peak was formed under favorable conditions.
1993, 11(2): 115-120
Abstract:
13C-NMR chemical shifts of model compound of a novel side chain liquid crystalline polymer, poly 2.5-his (4-alkoxybenzoyloxy) styrene , have been assigned in this study. Moreover, by using high-resolution solid-state CP/MAS (cross polarization/magic angle spinning) technique, the spectrum shows that in the crystalline state the ester linkage has a conformation nearly perpendicular to the either side of ring planes, and that the alkoxy groups are not fully in zigzag form. The possible conformational changes around the mesogens from the solid state to the mesophase are discussed.
13C-NMR chemical shifts of model compound of a novel side chain liquid crystalline polymer, poly 2.5-his (4-alkoxybenzoyloxy) styrene , have been assigned in this study. Moreover, by using high-resolution solid-state CP/MAS (cross polarization/magic angle spinning) technique, the spectrum shows that in the crystalline state the ester linkage has a conformation nearly perpendicular to the either side of ring planes, and that the alkoxy groups are not fully in zigzag form. The possible conformational changes around the mesogens from the solid state to the mesophase are discussed.
1993, 11(2): 121-124
Abstract:
The gas separation properties of free- standing film of polyaniline (PANI) for gas pairs of He/N2, H2/N2. CO2/N2 and CO2/CH4 at room temperature were measured as a function of the protonation state. Variation of the gas permeabilities coefficient of PANI with an insulator to metal transition upon the protonation processes was observed, which might be due to a change in both gas solubility coefficient and diffusion coefficient with the protonation state.
The gas separation properties of free- standing film of polyaniline (PANI) for gas pairs of He/N2, H2/N2. CO2/N2 and CO2/CH4 at room temperature were measured as a function of the protonation state. Variation of the gas permeabilities coefficient of PANI with an insulator to metal transition upon the protonation processes was observed, which might be due to a change in both gas solubility coefficient and diffusion coefficient with the protonation state.
1993, 11(2): 125-132
Abstract:
A new differential equation was derived from the modified first-order kinetic model to describe the polymer crystallization processes. The crystallization experiments were carried out by means of DSC. Poly (ethylene terephthalate) resins were selected as the samples containing different catalysts. The relationships between the parameters obtained from the known Avrami equation and from one in the present paper were discussed. A method for applying the equation to determine the kinetic parameters from a constant heating and a constant cooling curve was proposed.
A new differential equation was derived from the modified first-order kinetic model to describe the polymer crystallization processes. The crystallization experiments were carried out by means of DSC. Poly (ethylene terephthalate) resins were selected as the samples containing different catalysts. The relationships between the parameters obtained from the known Avrami equation and from one in the present paper were discussed. A method for applying the equation to determine the kinetic parameters from a constant heating and a constant cooling curve was proposed.
1993, 11(2): 133-143
Abstract:
The mechanical relaxation time of a two-component epoxy network-LiClO4 system as a polymer electrolyte was investigated. The network is composed of diglycidyl ether of polyethylene glycol (DGEPEG) and triglycidyl ether of glycerol (TGEG), wherein LiCIO4 was incorporated and acts as both the ionic carrier and the curing catalyst. As the relaxation time is informative to the segmental mobility, which is known to be essential for ionic conductivity, the average relaxation times of the specimens were determined through master curve construction.Experimental results showed that the salt concentration,molecular weight of PEG in DGEPEG and DGEPEG/TGEG ratio have profound effect on the relaxation time of the specimen.Among these factors,the former reinforces the network chains,leading to lengthen the relaxation time,whereas the latter two are in favour of the chain flexibility and show an opposite effect.The findings was rationalized in terms of the free volume concept.
The mechanical relaxation time of a two-component epoxy network-LiClO4 system as a polymer electrolyte was investigated. The network is composed of diglycidyl ether of polyethylene glycol (DGEPEG) and triglycidyl ether of glycerol (TGEG), wherein LiCIO4 was incorporated and acts as both the ionic carrier and the curing catalyst. As the relaxation time is informative to the segmental mobility, which is known to be essential for ionic conductivity, the average relaxation times of the specimens were determined through master curve construction.Experimental results showed that the salt concentration,molecular weight of PEG in DGEPEG and DGEPEG/TGEG ratio have profound effect on the relaxation time of the specimen.Among these factors,the former reinforces the network chains,leading to lengthen the relaxation time,whereas the latter two are in favour of the chain flexibility and show an opposite effect.The findings was rationalized in terms of the free volume concept.
1993, 11(2): 144-152
Abstract:
A novel radical grafting copolymerization process has been designed for water-soluble polymers which avoids the problems of conducting grafting reactions in highly viscous polymerization media. A variety of water-soluble graft copolymers having starch or dextran as the backbone chain with grafted side chains of polyacrylamide (—AM—), poly (acrylic acid ) (—AA—), poly (acrylamide-co-acrylic acid) (—AM—NH4AA—) or poly ( acrylamide-co-2-acryiamido-2-methyl-l-propanesulphinic acid) (—AM—AMPS—) have been synthesized in gel droplets using a ceric sulphate redox initiator,and their properties compared.The reaction conditions were optimized taking into account reaction kinetic data and the observed properties of the products produced under different reaction conditions.The effects of the ratios of [backbone]/[graft monomer],[AM]/[AA]/[AMPS],[Ce4+]/[S2O8] nad pH value on the reaction rate,conversion,grafting degree,grafted chain length and the product molecular weight have been investigated.
A novel radical grafting copolymerization process has been designed for water-soluble polymers which avoids the problems of conducting grafting reactions in highly viscous polymerization media. A variety of water-soluble graft copolymers having starch or dextran as the backbone chain with grafted side chains of polyacrylamide (—AM—), poly (acrylic acid ) (—AA—), poly (acrylamide-co-acrylic acid) (—AM—NH4AA—) or poly ( acrylamide-co-2-acryiamido-2-methyl-l-propanesulphinic acid) (—AM—AMPS—) have been synthesized in gel droplets using a ceric sulphate redox initiator,and their properties compared.The reaction conditions were optimized taking into account reaction kinetic data and the observed properties of the products produced under different reaction conditions.The effects of the ratios of [backbone]/[graft monomer],[AM]/[AA]/[AMPS],[Ce4+]/[S2O8] nad pH value on the reaction rate,conversion,grafting degree,grafted chain length and the product molecular weight have been investigated.
1993, 11(2): 153-157
Abstract:
The novel cyclic monomer, 2-oxo-3-methylene-5-phenyl-1,4-dioxan, was synthesized by a set of reactions. Several intermediates were prepared and characterized in order to determine the monomer structure. The presence of chiral centers in the intermediates and resulting monomer makes it complicated to separate , purify and characterize them. It is a very reactive monomer which will polymerize even at room temperature if expose to moisture and air. This monomer can undergo essentially quantitative flee radical ring opening polymerization.The driving force for ring opening is the formation of new carbonyl group and benzylic radical.The monomer and polymer structure were estabished by IR,1H NMR,13C NMR and elemental analysis or high resolution mass spectrum.The molecular weight of the resulting polymer was estimated by viscosity determination.
The novel cyclic monomer, 2-oxo-3-methylene-5-phenyl-1,4-dioxan, was synthesized by a set of reactions. Several intermediates were prepared and characterized in order to determine the monomer structure. The presence of chiral centers in the intermediates and resulting monomer makes it complicated to separate , purify and characterize them. It is a very reactive monomer which will polymerize even at room temperature if expose to moisture and air. This monomer can undergo essentially quantitative flee radical ring opening polymerization.The driving force for ring opening is the formation of new carbonyl group and benzylic radical.The monomer and polymer structure were estabished by IR,1H NMR,13C NMR and elemental analysis or high resolution mass spectrum.The molecular weight of the resulting polymer was estimated by viscosity determination.
1993, 11(2): 158-162
Abstract:
A program of Monte Carlo simulation of binary copolymerization for E-SBR (emulsion polymn. SB rubber) was made according to the terminal model. The simulation results obtained by this program were in good agreement with those experimental ones. A detail microstructure information of E-SBR molecular chain has been provided.
A program of Monte Carlo simulation of binary copolymerization for E-SBR (emulsion polymn. SB rubber) was made according to the terminal model. The simulation results obtained by this program were in good agreement with those experimental ones. A detail microstructure information of E-SBR molecular chain has been provided.
1993, 11(2): 163-170
Abstract:
Several dimethylamino-substituted chalcone (i .e. dimethylaminobenzal acetophenone) (DBA) derivatives with intramolecular charge transfer transition character were used as visible light sensitizers for radical photopolymerization initiated by iodonium salt (DPIO). Initiating radical species is produced from DBA sensitized photolysis of DPIO through the single electron transfer, accompanying the bleaching of DBA, The activity of DBA decreases as a function of substituent attached to phenyl ring in the order:DBA-2(OCH3)>DBA-1(H)>DBA-3(C1).The kinetic study on photopolymerization of MMA was carried out in CH3CN solution at 30℃ by dilatometry.The polymerization rate was determined to be proportional to the concentration with exponents of 0.42,0.25 and 0.86 for SPIO,DBA-1 and MMA,respectively.
Several dimethylamino-substituted chalcone (i .e. dimethylaminobenzal acetophenone) (DBA) derivatives with intramolecular charge transfer transition character were used as visible light sensitizers for radical photopolymerization initiated by iodonium salt (DPIO). Initiating radical species is produced from DBA sensitized photolysis of DPIO through the single electron transfer, accompanying the bleaching of DBA, The activity of DBA decreases as a function of substituent attached to phenyl ring in the order:DBA-2(OCH3)>DBA-1(H)>DBA-3(C1).The kinetic study on photopolymerization of MMA was carried out in CH3CN solution at 30℃ by dilatometry.The polymerization rate was determined to be proportional to the concentration with exponents of 0.42,0.25 and 0.86 for SPIO,DBA-1 and MMA,respectively.
1993, 11(2): 171-177
Abstract:
Poly(lithium propionate methyl siloxane )as a single-ion carrier source was synthesized. The crosslinked film showed lower lithium ionic conductivity at room temperature (about 10-10 S/cm). However,the lithium ionic conductivity was obviously increased by blending with high polar polymers such as polyethylene oxide, poly (methylsiloxane - co- ethylene oxide) and poly (methylsiloxane- g- ethylene oxide). In the blend system a high conductivity of 10-7-10-5 Scm-1 at room temperature was obtained and the single-ion conductivity was deeply influenced by the content of the poly (lithium propionate methyl siloxane).The dc ionic conductivity of the flexible crosslinked films is more stable over time.
Poly(lithium propionate methyl siloxane )as a single-ion carrier source was synthesized. The crosslinked film showed lower lithium ionic conductivity at room temperature (about 10-10 S/cm). However,the lithium ionic conductivity was obviously increased by blending with high polar polymers such as polyethylene oxide, poly (methylsiloxane - co- ethylene oxide) and poly (methylsiloxane- g- ethylene oxide). In the blend system a high conductivity of 10-7-10-5 Scm-1 at room temperature was obtained and the single-ion conductivity was deeply influenced by the content of the poly (lithium propionate methyl siloxane).The dc ionic conductivity of the flexible crosslinked films is more stable over time.
1993, 11(2): 178-184
Abstract:
The potyelectrolyte of propane sulfonate(PS) grafted PPTA copolymers——PPTA-PS, PPTA[O]-PS, PPTA[C]-PS were prepared and used as electrolyte in the process of electrochemical polymerization of pyrrole to form the molecular composite polypyrrole (PPY)/Polyelectrolyte.The preparation and liquid crystalline property of three kinds of polyelectrolyte, the electrical conductivity, mechanical properties, SEM and thermoproperties of PPY/polyelectrolyte are presented in detail.
The potyelectrolyte of propane sulfonate(PS) grafted PPTA copolymers——PPTA-PS, PPTA[O]-PS, PPTA[C]-PS were prepared and used as electrolyte in the process of electrochemical polymerization of pyrrole to form the molecular composite polypyrrole (PPY)/Polyelectrolyte.The preparation and liquid crystalline property of three kinds of polyelectrolyte, the electrical conductivity, mechanical properties, SEM and thermoproperties of PPY/polyelectrolyte are presented in detail.
1993, 11(2): 185-192
Abstract:
In this paper, the poling properties of (PS)O-DCV, a derivative of poly (p-hydroxystyrene ), was reported. The investigations showed that the thermochromism correction, which was neglected in the literatures, should be considered in the measurements of order parameter of poled films with electrochromism technique Here, another linear optical method, IR and polarized IR spectra for characterizing of poled films was suggested first time. The bulk second nonlinear optical coefficient d33 of poled films could be estimated by measured order parameter semi-qualitatively.
In this paper, the poling properties of (PS)O-DCV, a derivative of poly (p-hydroxystyrene ), was reported. The investigations showed that the thermochromism correction, which was neglected in the literatures, should be considered in the measurements of order parameter of poled films with electrochromism technique Here, another linear optical method, IR and polarized IR spectra for characterizing of poled films was suggested first time. The bulk second nonlinear optical coefficient d33 of poled films could be estimated by measured order parameter semi-qualitatively.
