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1997 Volume 14 Issue 2
1997, 14(2): 1-4
Abstract:
New catalysts composed of Ln(acac)3 and BuMgCl have been successfully developed for the polymerization of methyl methacrylate(MMA). The effects of various rare earth elements, catalyst aging time and temperature, catalyst concentration, various solvents, CCl4 additive, polymerization time and temperature on the polymerization of MMA were studied in detail. The results showed that the polymerization conversion of MMA in petroleum ether was higher than that in aromatic hydrocarbons and other polar solvents. The excessive BuMgCl may act as chain transfer agent. Lower polymerization temperature is preferable for increasing syndiotactic content of PMMA.
New catalysts composed of Ln(acac)3 and BuMgCl have been successfully developed for the polymerization of methyl methacrylate(MMA). The effects of various rare earth elements, catalyst aging time and temperature, catalyst concentration, various solvents, CCl4 additive, polymerization time and temperature on the polymerization of MMA were studied in detail. The results showed that the polymerization conversion of MMA in petroleum ether was higher than that in aromatic hydrocarbons and other polar solvents. The excessive BuMgCl may act as chain transfer agent. Lower polymerization temperature is preferable for increasing syndiotactic content of PMMA.
1997, 14(2): 5-7
Abstract:
X-Caprolactone/d,l-lactide copolymers with different compositions have been synthesized with a novel rare earth coordination catalyst composed of yttrium trifluoroacetate Y(CF3COO)3 and triisobutylaluminum Al(i-Bu)3, and characterized by GPC and 1H NMR. The results show that the chemical compositions of X-caprolactone/d,l lactide copolymers can be adjusted by changing the monomer weight ratio in feed, and morphology of the copolymer is influenced greatly by the composition.
X-Caprolactone/d,l-lactide copolymers with different compositions have been synthesized with a novel rare earth coordination catalyst composed of yttrium trifluoroacetate Y(CF3COO)3 and triisobutylaluminum Al(i-Bu)3, and characterized by GPC and 1H NMR. The results show that the chemical compositions of X-caprolactone/d,l lactide copolymers can be adjusted by changing the monomer weight ratio in feed, and morphology of the copolymer is influenced greatly by the composition.
1997, 14(2): 8-12
Abstract:
The preparation of water-containing diesel oil emulsion and microemulsion by using nonionic surfactants as emulsifiers was studied. The combustion heat of water-doped diesel oil was measured under different combustion conditions. The results showed that the incorporation of water in diesel oil did not improve the combustion efficiency under rich oxygen condition(in the oxygen bomb), but the calorific efficiency was improved when the diesel oil containing water was atomized directly into the combustion chamber under atmospheric condition. To get a higher combustion efficiency, the amount of water incorporated in diesel oil generally should be about 10%~20%, but it can be up to 30% in the presence of some metallic ions in water. The diesel oil microemulsion is much more stable than the emulsion containing equal content of water, but the combustion heat in both of them is all the same.
The preparation of water-containing diesel oil emulsion and microemulsion by using nonionic surfactants as emulsifiers was studied. The combustion heat of water-doped diesel oil was measured under different combustion conditions. The results showed that the incorporation of water in diesel oil did not improve the combustion efficiency under rich oxygen condition(in the oxygen bomb), but the calorific efficiency was improved when the diesel oil containing water was atomized directly into the combustion chamber under atmospheric condition. To get a higher combustion efficiency, the amount of water incorporated in diesel oil generally should be about 10%~20%, but it can be up to 30% in the presence of some metallic ions in water. The diesel oil microemulsion is much more stable than the emulsion containing equal content of water, but the combustion heat in both of them is all the same.
1997, 14(2): 13-15
Abstract:
Glycerin T-monobutyl ether, T-monohexyl ether, T-monoheptyl ether and T-monooctyl ether were synthesized and used as the plasticizers of regenerated cellulose films. The structure and properties of plasticized films were studied by FT-IR, DTA and mechanical strength measurement. Experimental results showed that these four glycerin T-monoethers had good plasticization effects on the films. With increasing number of carbon atoms of etheric moiety, the interaction between molecules of plasticizer and cellulose increased and plasticization effects decreased. The resistance against water washing of regenerated cellulose films plasticized by glycerin T-monohexyl ether, T-monoheptyl ether and T-monoctyl ether was obviously higher than that of the films plasticized by glycerin.
Glycerin T-monobutyl ether, T-monohexyl ether, T-monoheptyl ether and T-monooctyl ether were synthesized and used as the plasticizers of regenerated cellulose films. The structure and properties of plasticized films were studied by FT-IR, DTA and mechanical strength measurement. Experimental results showed that these four glycerin T-monoethers had good plasticization effects on the films. With increasing number of carbon atoms of etheric moiety, the interaction between molecules of plasticizer and cellulose increased and plasticization effects decreased. The resistance against water washing of regenerated cellulose films plasticized by glycerin T-monohexyl ether, T-monoheptyl ether and T-monoctyl ether was obviously higher than that of the films plasticized by glycerin.
1997, 14(2): 16-19
Abstract:
Double ionic conducting AB crosslinked polyether solid electrolytes(ABCPE2) and electrorheological(ER) fluids based on ABCPE2 were synthesized by solution polymerization or inverse suspension polymerization of T,k-bismethacryloyl capped poly(ethylene oxide), which has been mixed with LiClO4. Ionic conductivity of ABCPE2 as well as ER effect and electric current density of ER fluids based on ABCPE2 were studied, in the meantime, the shape and sizes of particles in the ER fluids were observed with scanning electronic microscopy. As a result, ABCPE2 with high ionic conductivity of 8.0×10-5 S/cm(25℃) was obtained as well as ER fluid with relative high activity.
Double ionic conducting AB crosslinked polyether solid electrolytes(ABCPE2) and electrorheological(ER) fluids based on ABCPE2 were synthesized by solution polymerization or inverse suspension polymerization of T,k-bismethacryloyl capped poly(ethylene oxide), which has been mixed with LiClO4. Ionic conductivity of ABCPE2 as well as ER effect and electric current density of ER fluids based on ABCPE2 were studied, in the meantime, the shape and sizes of particles in the ER fluids were observed with scanning electronic microscopy. As a result, ABCPE2 with high ionic conductivity of 8.0×10-5 S/cm(25℃) was obtained as well as ER fluid with relative high activity.
1997, 14(2): 20-23
Abstract:
Nickel-palladium alloy film was prepared on p-type silicon using potential-controlled electrodeposition. Cathodic deposition and anodic stripping behavior were investigated as well. The influence of polarization style on the composition, thickness, morphology and structure of film was studied by means of energy dispersive X-ray analysis, X-ray diffraction (XRD) and scanning electron microscope(SEM). SEM showed that at the initial stage nickel-palladium forms a layered structure, with the film growing and the polarization enhanced, an island growth was found. XRD indicated that nickel-palladium alloy has a face-centered cubic structure and the distance between crystal planes changes with the composition of deposit.
Nickel-palladium alloy film was prepared on p-type silicon using potential-controlled electrodeposition. Cathodic deposition and anodic stripping behavior were investigated as well. The influence of polarization style on the composition, thickness, morphology and structure of film was studied by means of energy dispersive X-ray analysis, X-ray diffraction (XRD) and scanning electron microscope(SEM). SEM showed that at the initial stage nickel-palladium forms a layered structure, with the film growing and the polarization enhanced, an island growth was found. XRD indicated that nickel-palladium alloy has a face-centered cubic structure and the distance between crystal planes changes with the composition of deposit.
1997, 14(2): 24-27
Abstract:
The comblike polymers with carboxylate groups and poly(ethylene oxide) side chains have been synthesized by alcoholysis of maleic anhydride-vinyl acetate copolymers with PEO monoether. The plasticized alkali polymer salt films showed conductivity up to 10-5 S/cm at room temperature. It was found that the conductivity increased when the length of the side chains increased appropriately. The effects of plasticizer, cation radius, temperature and frequency on the conductivity were also investigated.
The comblike polymers with carboxylate groups and poly(ethylene oxide) side chains have been synthesized by alcoholysis of maleic anhydride-vinyl acetate copolymers with PEO monoether. The plasticized alkali polymer salt films showed conductivity up to 10-5 S/cm at room temperature. It was found that the conductivity increased when the length of the side chains increased appropriately. The effects of plasticizer, cation radius, temperature and frequency on the conductivity were also investigated.
1997, 14(2): 28-31
Abstract:
A new fluorescent reagent, salicylaldehyde-5-bromo salicyloylhydrazone(SABSH), was synthesized and the fluorigenic reaction of this reagent with zinc was studied in detail. Based on this chelation reaction, a spectrofluorimetric method was developed for the determination of zinc in a 2-propanol-water(1:1, V/V) medium at pH 7.9. Under these conditions the Zn SABSH complex has excitation and emission maxima at 393 nm and 465 nm, respectively. The linear range of the method is from 0 to 400 μg/L, the relative standard deviation of the method is 1.2% and the detection limit is 1.3 μg/L of zinc when a standard addition method is used in the assay. The molar ratio of zinc to reagent is 1:2. Interferences of thirty six other ions were studied. The method has been successfully applied to the determination of trace zinc in wheat flour, rice, human urine and mineral spring water samples.
A new fluorescent reagent, salicylaldehyde-5-bromo salicyloylhydrazone(SABSH), was synthesized and the fluorigenic reaction of this reagent with zinc was studied in detail. Based on this chelation reaction, a spectrofluorimetric method was developed for the determination of zinc in a 2-propanol-water(1:1, V/V) medium at pH 7.9. Under these conditions the Zn SABSH complex has excitation and emission maxima at 393 nm and 465 nm, respectively. The linear range of the method is from 0 to 400 μg/L, the relative standard deviation of the method is 1.2% and the detection limit is 1.3 μg/L of zinc when a standard addition method is used in the assay. The molar ratio of zinc to reagent is 1:2. Interferences of thirty six other ions were studied. The method has been successfully applied to the determination of trace zinc in wheat flour, rice, human urine and mineral spring water samples.
1997, 14(2): 32-35
Abstract:
Carbon nanotubes have been produced by catalytic pyrolysis of n-butene on solid acid catalyst at first time. The solid acid catalysts were fluorinated V-Al2O3 and HZSM-5 zeolites which did not contain metal particles, as ordinary used in the production of carbon nanotubes. In comparison with the metal particle catalysts, the carbon nanotubes produced in this condition require much lower pyrolysis temperature. The production was found to correlate with acid strength and acid sites of the solid acid catalysts. Some carbon nanotubes with special structures have been distinguished.
Carbon nanotubes have been produced by catalytic pyrolysis of n-butene on solid acid catalyst at first time. The solid acid catalysts were fluorinated V-Al2O3 and HZSM-5 zeolites which did not contain metal particles, as ordinary used in the production of carbon nanotubes. In comparison with the metal particle catalysts, the carbon nanotubes produced in this condition require much lower pyrolysis temperature. The production was found to correlate with acid strength and acid sites of the solid acid catalysts. Some carbon nanotubes with special structures have been distinguished.
1997, 14(2): 36-39
Abstract:
The effects of partially hydrolyzed polyacrylamide(HPAM), xanthan gum(XC) and lignosulfonate(LS) on the middle phase microemulsion containing petroleum sulfonate, mixed n-butyl and i-propyl alcohols and mineralized water have been studied by phase volume, interfacial tension(IFT), viscosity and solubilizing parameter measurements. Introducing polymers into the microemulsion caused slight increase of IFT, and no obvious change was observed in viscosity of middle phase. The volume of the middle phase microemulsion was decreased as the concentration of HPAM increased. Increase of LS led to disapearing of middle phase, forming Winsor 2 microemulsion system.
The effects of partially hydrolyzed polyacrylamide(HPAM), xanthan gum(XC) and lignosulfonate(LS) on the middle phase microemulsion containing petroleum sulfonate, mixed n-butyl and i-propyl alcohols and mineralized water have been studied by phase volume, interfacial tension(IFT), viscosity and solubilizing parameter measurements. Introducing polymers into the microemulsion caused slight increase of IFT, and no obvious change was observed in viscosity of middle phase. The volume of the middle phase microemulsion was decreased as the concentration of HPAM increased. Increase of LS led to disapearing of middle phase, forming Winsor 2 microemulsion system.
1997, 14(2): 40-44
Abstract:
The effects of the adsorption and surface micellization of dodecylpyridinium bromide(DPB) on the stability of silica(CAB-O-SIL) suspension have been investigated. The adsorption isotherms of DPB on a flame-hydrolyzed silica from aqueous solution exhibit two plateau(i.e.LS-type isotherm). In the presence of 0.1 mol/L NaBr the adsorption isotherm of DPB is displaced to lower equilibrium concentration region and the limiting adsorption is enhanced, but the adsorption in the first plateau remains nearly constant. In the low concentration range of DPB, the stability of silica suspension decreases with increasing concentration of DPB. However, near smc (surface micelle concentration) of DPB the stability increases sharply with increasing concentration of DPB. In the presence of NaBr, the stability of silica suspension is much lower in comparison with that without addcd salt. The results are explained in terms of the surface micellization model and the adsorption isotherms of DPB.
The effects of the adsorption and surface micellization of dodecylpyridinium bromide(DPB) on the stability of silica(CAB-O-SIL) suspension have been investigated. The adsorption isotherms of DPB on a flame-hydrolyzed silica from aqueous solution exhibit two plateau(i.e.LS-type isotherm). In the presence of 0.1 mol/L NaBr the adsorption isotherm of DPB is displaced to lower equilibrium concentration region and the limiting adsorption is enhanced, but the adsorption in the first plateau remains nearly constant. In the low concentration range of DPB, the stability of silica suspension decreases with increasing concentration of DPB. However, near smc (surface micelle concentration) of DPB the stability increases sharply with increasing concentration of DPB. In the presence of NaBr, the stability of silica suspension is much lower in comparison with that without addcd salt. The results are explained in terms of the surface micellization model and the adsorption isotherms of DPB.
1997, 14(2): 45-49
Abstract:
Twenty one new O-(1,2,2,2 tetrachloro) ethyl-O-substituted-phenyl-phospho-ramidothionates were synthesized and their structures were characterized through IR, NMR(1H、31 P) and MS. The O-(1,2,2,2-tetrachloro) ethyl-thiophosphoric hydrazides could be transferred into 1,3,4,2-oxadiazaphospholanes under alkaline condition. The biological activity of the products was also tested and some compounds showed a high activity against nematode.
Twenty one new O-(1,2,2,2 tetrachloro) ethyl-O-substituted-phenyl-phospho-ramidothionates were synthesized and their structures were characterized through IR, NMR(1H、31 P) and MS. The O-(1,2,2,2-tetrachloro) ethyl-thiophosphoric hydrazides could be transferred into 1,3,4,2-oxadiazaphospholanes under alkaline condition. The biological activity of the products was also tested and some compounds showed a high activity against nematode.
1997, 14(2): 50-52
Abstract:
Seven bulkier substitute titanocene and zirconocene dichlorides have been synthesized by addition reaction of 6,6-dialkylfulvenes with 1-lithiocyclohexene followed by treatment of the obtained bulkier substituted metallocene with MCl4(M=Ti, Zr). Their 1H NMR, EIMS and IR spectra have been discussed.
Seven bulkier substitute titanocene and zirconocene dichlorides have been synthesized by addition reaction of 6,6-dialkylfulvenes with 1-lithiocyclohexene followed by treatment of the obtained bulkier substituted metallocene with MCl4(M=Ti, Zr). Their 1H NMR, EIMS and IR spectra have been discussed.
1997, 14(2): 53-56
Abstract:
In the paper the miscibility of carboxylated poly(phenylene oxide) (CPPO)/poly(styrene-co-4-vinylpyridine) (PSVP) blends was investigated by DSC and DMA. It was found that the CPPO/PSVP blends possessed relatively good miscibility compared with CPPO/PS, and this was attributed to the ion-ion interactions resulted from the proton transfer between the carboxylic groups of CPPO and the pyridine groups of PSVP.
In the paper the miscibility of carboxylated poly(phenylene oxide) (CPPO)/poly(styrene-co-4-vinylpyridine) (PSVP) blends was investigated by DSC and DMA. It was found that the CPPO/PSVP blends possessed relatively good miscibility compared with CPPO/PS, and this was attributed to the ion-ion interactions resulted from the proton transfer between the carboxylic groups of CPPO and the pyridine groups of PSVP.
1997, 14(2): 57-59
Abstract:
Cu/SiO2 catalysts modified by Cr2O3 and MoO3 have been characterized with a continuous fixed-bed reactor. The influence of Cr2O3 and MoO3 on the surface properties and active site of catalysts has also been studied with TPR, XPS and XRD. The results show that catalytic properties of catalysts modified by Cr and Mo are improved remarkably and Cr2O3 and MoO3 in the catalysts have the property of donating electrons towards Cu particles. Adding proper amounts of Cr, Mo to catalysts can increase the dispersity of Cu particles and the stability of catalysts.
Cu/SiO2 catalysts modified by Cr2O3 and MoO3 have been characterized with a continuous fixed-bed reactor. The influence of Cr2O3 and MoO3 on the surface properties and active site of catalysts has also been studied with TPR, XPS and XRD. The results show that catalytic properties of catalysts modified by Cr and Mo are improved remarkably and Cr2O3 and MoO3 in the catalysts have the property of donating electrons towards Cu particles. Adding proper amounts of Cr, Mo to catalysts can increase the dispersity of Cu particles and the stability of catalysts.
1997, 14(2): 60-62
Abstract:
The preparation and characterization of a series of dinuclear copper(Ⅱ) complexes, Cu2L2IA(ClO4)2, are presented. The ligand L is 1,10-phenanthroline(phen), 5-nitro-1,10-phenanthroline(NO2-phen) and 2,2'-bipyridine, and IA denotes the dianion of iodanilic acid. The complexes are characterized by elemental analysis, IR, electronic spectra, ESR and variable-temperature magnetic susceptibility measurements. The coordination geometry of copper(Ⅱ) ion is probably a distorted square pyramid. Room-temperature ESR spectra of all the complexes studied show the ΔMs=±2 half-field transitions. The variable-temperature magnetic susceptibility of Cu2(phen)2IA(ClO4)2 had been measured (4.2~300 K) and the exchange parameter, J, was found to be -29.18 cm-1 using the Heisenberg model. This indicates that an antiferromagnetic interaction exists between the metal ions.
The preparation and characterization of a series of dinuclear copper(Ⅱ) complexes, Cu2L2IA(ClO4)2, are presented. The ligand L is 1,10-phenanthroline(phen), 5-nitro-1,10-phenanthroline(NO2-phen) and 2,2'-bipyridine, and IA denotes the dianion of iodanilic acid. The complexes are characterized by elemental analysis, IR, electronic spectra, ESR and variable-temperature magnetic susceptibility measurements. The coordination geometry of copper(Ⅱ) ion is probably a distorted square pyramid. Room-temperature ESR spectra of all the complexes studied show the ΔMs=±2 half-field transitions. The variable-temperature magnetic susceptibility of Cu2(phen)2IA(ClO4)2 had been measured (4.2~300 K) and the exchange parameter, J, was found to be -29.18 cm-1 using the Heisenberg model. This indicates that an antiferromagnetic interaction exists between the metal ions.
1997, 14(2): 63-65
Abstract:
The organoclay has been prepared from short chain alkylammonium ion exchanged montmorillonite. The clay nanolayers can be homogeneously dispersed in epoxy matrix under curing in polyetheramine at 125℃. The organoclay structure and molecular dispersion of the layered silicates were verified using X-ray diffraction. Better reinforcement mechanical proporties for short chain molecule exchanged organoclay have been achieved.
The organoclay has been prepared from short chain alkylammonium ion exchanged montmorillonite. The clay nanolayers can be homogeneously dispersed in epoxy matrix under curing in polyetheramine at 125℃. The organoclay structure and molecular dispersion of the layered silicates were verified using X-ray diffraction. Better reinforcement mechanical proporties for short chain molecule exchanged organoclay have been achieved.
1997, 14(2): 66-68
Abstract:
Thermokinetic properties of the reaction between laccase and 3,4-dihydroxyben-zaldehyde have been studied with a microcalorimetry system. The molar reaction enthalpy(ΔrHm), michaelis constant(Km), rate constant(k2), binding energy(ΔG0), activation gibbis free energy(ΔG=) and laccase activity(EA) have been determined. The result has been discussed by the transition state theory.
Thermokinetic properties of the reaction between laccase and 3,4-dihydroxyben-zaldehyde have been studied with a microcalorimetry system. The molar reaction enthalpy(ΔrHm), michaelis constant(Km), rate constant(k2), binding energy(ΔG0), activation gibbis free energy(ΔG=) and laccase activity(EA) have been determined. The result has been discussed by the transition state theory.
1997, 14(2): 69-71
Abstract:
The anionic block copolymerization of MMA and C7~9 methacrylate (C7~9 MA) was studied using n-BuLi as initiator. PC7~9 MA-b-PMMA copolymer was obtained. The influences of sequence in monomer-feed, temperature, concentration of initiator and active chain length of PC7~9 MA- on block copolymerization were discussed. When T=-20℃,[I]=(5.30±0.04)×10-2 mol/L and C7~9 MA as first monomer, PC7~9 MA- with Mn~1.6×104 was favorable to the copolymerization of PC7~9 MA-b-PMMA. The relative molecular mass and relative molecular mass distribution of copolymer were measured by GPC. The structure of block copolymer was characterized by FTIR and 1H NMR.
The anionic block copolymerization of MMA and C7~9 methacrylate (C7~9 MA) was studied using n-BuLi as initiator. PC7~9 MA-b-PMMA copolymer was obtained. The influences of sequence in monomer-feed, temperature, concentration of initiator and active chain length of PC7~9 MA- on block copolymerization were discussed. When T=-20℃,[I]=(5.30±0.04)×10-2 mol/L and C7~9 MA as first monomer, PC7~9 MA- with Mn~1.6×104 was favorable to the copolymerization of PC7~9 MA-b-PMMA. The relative molecular mass and relative molecular mass distribution of copolymer were measured by GPC. The structure of block copolymer was characterized by FTIR and 1H NMR.
Laser-induced Electropolymerization of Pyrrole and o-Phenylenediamine for Micro-patterns Fabrication
1997, 14(2): 72-74
Abstract:
It has been shown that laser can induce selective local electropolymerization of polypyrrole (PPY) and poly-o-phenylenediamine(POPD). The resonance Raman spectroscopic result indicates that the structure of the laser-induced PPY is nearly identical to that of the PPY formed under the normal condition of electropolymerization. It seems to be reasonable to assume that the laser induced thermal effect is most likely to influence the electropolymerization kinetics, as the temperature rise at the illuminated surface area results in considerable shift of the equilibrium potential. Electrochemical micro-patterns were achieved by laser-induced electropolymerization of PPY and POPD on Au and HOPG electrode. The diameter of points and the width of lines obtained are about 2~4 and 8 micrometers respectively.
It has been shown that laser can induce selective local electropolymerization of polypyrrole (PPY) and poly-o-phenylenediamine(POPD). The resonance Raman spectroscopic result indicates that the structure of the laser-induced PPY is nearly identical to that of the PPY formed under the normal condition of electropolymerization. It seems to be reasonable to assume that the laser induced thermal effect is most likely to influence the electropolymerization kinetics, as the temperature rise at the illuminated surface area results in considerable shift of the equilibrium potential. Electrochemical micro-patterns were achieved by laser-induced electropolymerization of PPY and POPD on Au and HOPG electrode. The diameter of points and the width of lines obtained are about 2~4 and 8 micrometers respectively.
1997, 14(2): 75-77
Abstract:
In this paper, the surface reaction of NO thermal desorption and NO-CH4 reaction activity over Co-MgO catalyst were investigated. The adsorpted NO undergoes extensive decomposition to form N2 and N2O. There are two N2 peaks which are attributed to N(a)+NO(a)→N2+O(a) and 2N(a)→N2 reactions, respectively. There is only one N2O peak which is attributed to N(a)+NO(a)→N2O reaction. Because the O(a) produced during NO decomposition remains on Co microcrystallites, no O2 peak is observed. The ratio of CO2 and N2 in the products is near 1/2, which indicates that the reaction can be described as 4NO+CH4→2N2+CO2+H2O.
In this paper, the surface reaction of NO thermal desorption and NO-CH4 reaction activity over Co-MgO catalyst were investigated. The adsorpted NO undergoes extensive decomposition to form N2 and N2O. There are two N2 peaks which are attributed to N(a)+NO(a)→N2+O(a) and 2N(a)→N2 reactions, respectively. There is only one N2O peak which is attributed to N(a)+NO(a)→N2O reaction. Because the O(a) produced during NO decomposition remains on Co microcrystallites, no O2 peak is observed. The ratio of CO2 and N2 in the products is near 1/2, which indicates that the reaction can be described as 4NO+CH4→2N2+CO2+H2O.
1997, 14(2): 78-80
Abstract:
An acetoacetylated polyacrylate and a vinylic groups-ended polyurethane were synthesized. In the presence of a basic catalyst, they can crosslink with each other via the Michael reaction to prepare a thermoset coating at ambient temperature. A model of this crosslinking system, the reaction of ethyl acetoacetate (EAA) with methyl acrylate (MA), was designed to investigate the crosslinking mechanism. The results indicate that the two active hydrogen atoms of the acetoacetyl functionality can participate in the reaction and both mono-and bis-adducts are formed. The yield of bis-adduct increased with decreasing feeding molar ratio of EAA and MA. Two composite coatings with molar ratios of acetoacetyl content of polyacrylate to double bond content of polyurethane being 0 6/1 and 1/1 were prepared. The former coating showed higher crosslinking degree and better properties than the latter one.
An acetoacetylated polyacrylate and a vinylic groups-ended polyurethane were synthesized. In the presence of a basic catalyst, they can crosslink with each other via the Michael reaction to prepare a thermoset coating at ambient temperature. A model of this crosslinking system, the reaction of ethyl acetoacetate (EAA) with methyl acrylate (MA), was designed to investigate the crosslinking mechanism. The results indicate that the two active hydrogen atoms of the acetoacetyl functionality can participate in the reaction and both mono-and bis-adducts are formed. The yield of bis-adduct increased with decreasing feeding molar ratio of EAA and MA. Two composite coatings with molar ratios of acetoacetyl content of polyacrylate to double bond content of polyurethane being 0 6/1 and 1/1 were prepared. The former coating showed higher crosslinking degree and better properties than the latter one.
1997, 14(2): 81-83
Abstract:
This paper reports a buoyant photocatalyst of nano-sized TiO2 loaded on the hollow ceramic microbeads by silane coupling. The morphology was observed by SEM, and the amount of TiO2 bound to the beads was determined by spectrophotometry. Percentage moles of octane remaining in the solution phase after UV irradiation was analyzed by GC. It was observed that more than 90% of the octane photodecomposed in 60 min.
This paper reports a buoyant photocatalyst of nano-sized TiO2 loaded on the hollow ceramic microbeads by silane coupling. The morphology was observed by SEM, and the amount of TiO2 bound to the beads was determined by spectrophotometry. Percentage moles of octane remaining in the solution phase after UV irradiation was analyzed by GC. It was observed that more than 90% of the octane photodecomposed in 60 min.
1997, 14(2): 84-86
Abstract:
X-Caprolactone(X-CL)/d,l-lactide(DLLA) copolymer films with thickness of 40 μm were prepared by solution-casting and implanted into rabbit body to cover the ruptured achilles tendons for preventing tendon adhesion with surrounding tissues. The biodegradation of X-CL homopolymer film and X-CL/DLLA copolymer film in rabbit body were also studied. The X-CL/DLLA copolymer film could decrease postoperative adhesion of the tendon, and it degraded entirely within 24 weeks.
X-Caprolactone(X-CL)/d,l-lactide(DLLA) copolymer films with thickness of 40 μm were prepared by solution-casting and implanted into rabbit body to cover the ruptured achilles tendons for preventing tendon adhesion with surrounding tissues. The biodegradation of X-CL homopolymer film and X-CL/DLLA copolymer film in rabbit body were also studied. The X-CL/DLLA copolymer film could decrease postoperative adhesion of the tendon, and it degraded entirely within 24 weeks.
1997, 14(2): 87-89
Abstract:
Excimer fluorescence was used to probe the change of fluorescence intensity ratio of excimer/monomer chromophore IE/IM of poly(S-b-MMA) with concentration in THF solution. Three concentration regions are recognized in the range studied with respect to the values of IE/IM. In region Ⅰ, the values of IE/IM are independent of the concentration of the solution. In region Ⅱ, the IE/IM values increase with the increase of concentration. In region Ⅲ, the values of IE/IM almost keep constant. This phenomenon is attributed to the shrinkage of polymer coils and the entanglement of polymer chains at high concentration. The formation of micelles of the block copolymer in THF solution on addition of acetone was also studied. The change of IE/IM values indicates that the PS chains act as core and the PMMA chains as the corona.
Excimer fluorescence was used to probe the change of fluorescence intensity ratio of excimer/monomer chromophore IE/IM of poly(S-b-MMA) with concentration in THF solution. Three concentration regions are recognized in the range studied with respect to the values of IE/IM. In region Ⅰ, the values of IE/IM are independent of the concentration of the solution. In region Ⅱ, the IE/IM values increase with the increase of concentration. In region Ⅲ, the values of IE/IM almost keep constant. This phenomenon is attributed to the shrinkage of polymer coils and the entanglement of polymer chains at high concentration. The formation of micelles of the block copolymer in THF solution on addition of acetone was also studied. The change of IE/IM values indicates that the PS chains act as core and the PMMA chains as the corona.
1997, 14(2): 90-92
Abstract:
In this paper the pyrolytic process of polycarbosilane mixed with nano nickel particles was studied. This process involves two stages:the transition of organosilicon polymer to inorganic amorphous state and then to crystallite. The dominative form in pyrolytic products is Ni2Si. The addition of nano nickel particles accelerates the growth of U-SiC and the increase of crystallite size.
In this paper the pyrolytic process of polycarbosilane mixed with nano nickel particles was studied. This process involves two stages:the transition of organosilicon polymer to inorganic amorphous state and then to crystallite. The dominative form in pyrolytic products is Ni2Si. The addition of nano nickel particles accelerates the growth of U-SiC and the increase of crystallite size.
1997, 14(2): 93-95
Abstract:
Superfine V-MnO2 particles of different shape were obtained by reacting KMnO4 with H2O2 through controlling the reaction conditions. The formation process of the crystals has been studied and the materials were characterized by XRD, TEM, TG-DTA.
Superfine V-MnO2 particles of different shape were obtained by reacting KMnO4 with H2O2 through controlling the reaction conditions. The formation process of the crystals has been studied and the materials were characterized by XRD, TEM, TG-DTA.
1997, 14(2): 96-98
Abstract:
Twenty novel long-chain esters of substituted phenyl T-furoic acid have been synthesized. Their structures were confirmed by IR, 1H NMR and elemental analysis. The preliminary biological activity experiments showed that a certainly definite length of the ester chain is profitable.
Twenty novel long-chain esters of substituted phenyl T-furoic acid have been synthesized. Their structures were confirmed by IR, 1H NMR and elemental analysis. The preliminary biological activity experiments showed that a certainly definite length of the ester chain is profitable.
1997, 14(2): 99-101
Abstract:
A series of substituted cyclopentadienyllithium were prepared from exocyclic double-bond addition reaction of 6,6-dialkylfulvenes and 6,6-polymethy lenefulvenes with n-pentyllithium, 1-cyclohexenyllithium, 1,4-butylenedilithium and 1,6-hexylenedilithium, respectively. Reacting with CpTiCl3, they gave seventeen novel asymmetric titanocenes with bulky substituents. A general route for preparation of asymmetric titanocenes is herein reported.
A series of substituted cyclopentadienyllithium were prepared from exocyclic double-bond addition reaction of 6,6-dialkylfulvenes and 6,6-polymethy lenefulvenes with n-pentyllithium, 1-cyclohexenyllithium, 1,4-butylenedilithium and 1,6-hexylenedilithium, respectively. Reacting with CpTiCl3, they gave seventeen novel asymmetric titanocenes with bulky substituents. A general route for preparation of asymmetric titanocenes is herein reported.
1997, 14(2): 102-104
Abstract:
The application of poly(DL-lactide)(PLA) as a biodegradable ophthalmic implant has been studied. The PLA was synthesized from DL-lactide by bulk ring-opening polymerization initiated by stannous 2-ethylhexanoate. Both the pressure of polymerization system and the mole ratio of monomer to initiator showed a marked influence on the relative molecular weights of PLA. The in vitro and in vivo degradation of PLA has been investigated in 0.2 mol/L Na2HPO4-NaH2PO4 solution in rabbit's eyes.
The application of poly(DL-lactide)(PLA) as a biodegradable ophthalmic implant has been studied. The PLA was synthesized from DL-lactide by bulk ring-opening polymerization initiated by stannous 2-ethylhexanoate. Both the pressure of polymerization system and the mole ratio of monomer to initiator showed a marked influence on the relative molecular weights of PLA. The in vitro and in vivo degradation of PLA has been investigated in 0.2 mol/L Na2HPO4-NaH2PO4 solution in rabbit's eyes.
1997, 14(2): 105-107
Abstract:
Layered double hydroxides pillared with heteropolyanions have been studied using XPS、IR、XRD techniques, and the interaction between layers and pillars is discussed. The mechanism of this interaction is deduced mainly from XPS results.
Layered double hydroxides pillared with heteropolyanions have been studied using XPS、IR、XRD techniques, and the interaction between layers and pillars is discussed. The mechanism of this interaction is deduced mainly from XPS results.
1997, 14(2): 108-109
Abstract:
The polymerization of styrene initiated by divalent aryloxy samarium complex alone was studied for the first time. The effects of polymerization conditions on catalytic activity of the catalyst have been studied.
The polymerization of styrene initiated by divalent aryloxy samarium complex alone was studied for the first time. The effects of polymerization conditions on catalytic activity of the catalyst have been studied.
1997, 14(2): 110-112
Abstract:
V-FeOOH crystals were grown from FeSO4 by the air oxidation of ferrous hydroxide suspension in the presence of EDTA, and then 100% spindle T-Fe2O3 particles were prepared by adding 0.0025 mol/L hydroxyethylidene diphosphonic acid (HEDP) at 90~95℃. The mean particle length is 150~180 nm and the axial ratio is 3.5~3.8. A series of experiments were carried out with HEDP concentrations ranging from 0.0015 to 0.003 mol/L. The effect of HEDP concentration on T-Fe2O3 morphology is discussed.
V-FeOOH crystals were grown from FeSO4 by the air oxidation of ferrous hydroxide suspension in the presence of EDTA, and then 100% spindle T-Fe2O3 particles were prepared by adding 0.0025 mol/L hydroxyethylidene diphosphonic acid (HEDP) at 90~95℃. The mean particle length is 150~180 nm and the axial ratio is 3.5~3.8. A series of experiments were carried out with HEDP concentrations ranging from 0.0015 to 0.003 mol/L. The effect of HEDP concentration on T-Fe2O3 morphology is discussed.
1997, 14(2): 113-115
Abstract:
The removal of cytochrome c was investigated by multi-phase macroporous polyurethane resin. The domain structure of polyurethane resin provides a suitable morphological structure and affinity adsorption. The results show that the adsorption percentage is 96.6%.
The removal of cytochrome c was investigated by multi-phase macroporous polyurethane resin. The domain structure of polyurethane resin provides a suitable morphological structure and affinity adsorption. The results show that the adsorption percentage is 96.6%.
1997, 14(2): 116-117
Abstract:
Methylammonium chlorochromate adsorbed on alumina is prepared and evaluated as a convenient reagent for efficient oxidation of benzoins into corresponding benzils. This reagent is easily prepared, the oxidation condition is mild and the resulting oxidation products are easily separated.
Methylammonium chlorochromate adsorbed on alumina is prepared and evaluated as a convenient reagent for efficient oxidation of benzoins into corresponding benzils. This reagent is easily prepared, the oxidation condition is mild and the resulting oxidation products are easily separated.
1997, 14(2): 118-118
Abstract:
Composite coating of zinc and polyacrylate chains has been obtained through simultaneous zinc electrodeposition and electropolymerization of acrylate ions.
Composite coating of zinc and polyacrylate chains has been obtained through simultaneous zinc electrodeposition and electropolymerization of acrylate ions.
