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2004 Volume 21 Issue 2
2004, 21(2): 109-112
Abstract:
The title compound and its manganese(Ⅲ)complex MnL21Cl were prepared for catalytic epoxidation of styrene under the ambient temperature and pressure. The effects of reaction temperature, concentration of styrene, axial ligand, iodosobenzene and catalyst amount as well as the terminal group of the substituent bonded to the ligand on the biomimetic catalytic performance of the manganese(Ⅲ) complex were investigated. The result indicates that the catalytic activity(conv. of styrene 39.6%) of MnL21Cl, which contains hydroxyl group (OH) as the terminal group of the substituent bonded to the ligand is higher than that of containing acetoxyl group (CH3COO) as the terminal group, while the selectivity of epoxidation of (93.9%) is lower than that of MnL22Cl (100%) under the same optimization condition.
The title compound and its manganese(Ⅲ)complex MnL21Cl were prepared for catalytic epoxidation of styrene under the ambient temperature and pressure. The effects of reaction temperature, concentration of styrene, axial ligand, iodosobenzene and catalyst amount as well as the terminal group of the substituent bonded to the ligand on the biomimetic catalytic performance of the manganese(Ⅲ) complex were investigated. The result indicates that the catalytic activity(conv. of styrene 39.6%) of MnL21Cl, which contains hydroxyl group (OH) as the terminal group of the substituent bonded to the ligand is higher than that of containing acetoxyl group (CH3COO) as the terminal group, while the selectivity of epoxidation of (93.9%) is lower than that of MnL22Cl (100%) under the same optimization condition.
2004, 21(2): 113-116
Abstract:
The mechanism of the Cu2+ enriching process by chitosan as a flocculant chelating compound has been studied through morphological observation by AFM in noncontact mode. The colloid chitosan-Cu2+ aggregates were found to be regularly aligned. It could be further condensed by dehydration to from a more regular cyclic shape in small particle units. The process appears similar to that resulted by screw winding of particles. The higher concentrated sample is a regular disc-like shape. The range of disc diameters was between 35~50 μm.
The mechanism of the Cu2+ enriching process by chitosan as a flocculant chelating compound has been studied through morphological observation by AFM in noncontact mode. The colloid chitosan-Cu2+ aggregates were found to be regularly aligned. It could be further condensed by dehydration to from a more regular cyclic shape in small particle units. The process appears similar to that resulted by screw winding of particles. The higher concentrated sample is a regular disc-like shape. The range of disc diameters was between 35~50 μm.
2004, 21(2): 117-121
Abstract:
The behavior of quantized capacitance charging of the monolayer protected clusters(MPC) in tetrahydrofuran(THF) solution on the platinum ultramicroelectrode and bulk Pt electrode have been investigated for comparison. The results showed that MPC has many advantages over the bulk Pt electrode. With platinum microelectrode, there are six pairs of quantized capacitance charging peaks on the differential pulse cyclic voltammograms in 0.1 mol/L THF solution of hexanethiol protected MPC without electrolyte, and good electrochemical reversibility of the peaks could be observed even at high scan rate in cyclic voltammogram. The single potential step chronocoulometric experiments displayed that each quantized capacitance charging peak corresponds to one electron transfer across the interface of the MPC.
The behavior of quantized capacitance charging of the monolayer protected clusters(MPC) in tetrahydrofuran(THF) solution on the platinum ultramicroelectrode and bulk Pt electrode have been investigated for comparison. The results showed that MPC has many advantages over the bulk Pt electrode. With platinum microelectrode, there are six pairs of quantized capacitance charging peaks on the differential pulse cyclic voltammograms in 0.1 mol/L THF solution of hexanethiol protected MPC without electrolyte, and good electrochemical reversibility of the peaks could be observed even at high scan rate in cyclic voltammogram. The single potential step chronocoulometric experiments displayed that each quantized capacitance charging peak corresponds to one electron transfer across the interface of the MPC.
2004, 21(2): 122-125
Abstract:
Transparent SnO2 sols were obtained by a sol-gel method from SnCl2·2H2O in absolute ethanol, and SnO2 thin films were prepared by dip-coating technique. The microstructure of thin films has been studied by XRD、AFM and UV-Vis spectra analysis. The average size of the spherical SnO2 particles obtained is 5 nm. The absorbance of the film increases linearly with the ply deposited. The sheet resistance of the multi-ply SnO2 decreases with the increase of the film thickness to a constant value. The thin films have good sensitivity and response-recovery properties to ethanol and acetone from 100 to 1 000 μL/L at room temperature. The response and recovery times of the film to 800 μL/L gas are 30 and 60 s, respectively.
Transparent SnO2 sols were obtained by a sol-gel method from SnCl2·2H2O in absolute ethanol, and SnO2 thin films were prepared by dip-coating technique. The microstructure of thin films has been studied by XRD、AFM and UV-Vis spectra analysis. The average size of the spherical SnO2 particles obtained is 5 nm. The absorbance of the film increases linearly with the ply deposited. The sheet resistance of the multi-ply SnO2 decreases with the increase of the film thickness to a constant value. The thin films have good sensitivity and response-recovery properties to ethanol and acetone from 100 to 1 000 μL/L at room temperature. The response and recovery times of the film to 800 μL/L gas are 30 and 60 s, respectively.
2004, 21(2): 126-129
Abstract:
Three novel azo dyes, (2-(4-methyl-2-thiazolylazo)-5-diethylaminophenol,MTADP) and its nickel and zinc chelates have been synthesized. The structures of the compounds are characterized by elemental analysis, MS, FT-IR and FT-Raman spectroscopy. The UV-Vis absorption spectra indicated metal chelation results in about 60~70 nm bathochromic shift of absorption band. Bathochromic shift of Ni-MBADP is about 10 nm larger than that of Zn-MBADP. The decomposition temperature peak is observed at 331℃ for Ni-MTADP and 295℃ for Zn-MTADP by thermo-gravimetric analysis, respectively.
Three novel azo dyes, (2-(4-methyl-2-thiazolylazo)-5-diethylaminophenol,MTADP) and its nickel and zinc chelates have been synthesized. The structures of the compounds are characterized by elemental analysis, MS, FT-IR and FT-Raman spectroscopy. The UV-Vis absorption spectra indicated metal chelation results in about 60~70 nm bathochromic shift of absorption band. Bathochromic shift of Ni-MBADP is about 10 nm larger than that of Zn-MBADP. The decomposition temperature peak is observed at 331℃ for Ni-MTADP and 295℃ for Zn-MTADP by thermo-gravimetric analysis, respectively.
2004, 21(2): 130-134
Abstract:
The nanocomposites of epoxy resin/eleostearic anhydride/montmorillonite(EP/TOA/MMT) were prepared and studied by XRD and DSC. The XRD results showed it was an exfoliated nanocomposite. The dynamic curing information was obtained by nonisothermal DSC. It was found that addtion of montmorillonite accelerated the curing rate and facilitated the reaction. The activation energy, reaction order and other kinetic parameters were calculated by Flynn-Wall-Ozawa, Kissinger, Crane methods.
The nanocomposites of epoxy resin/eleostearic anhydride/montmorillonite(EP/TOA/MMT) were prepared and studied by XRD and DSC. The XRD results showed it was an exfoliated nanocomposite. The dynamic curing information was obtained by nonisothermal DSC. It was found that addtion of montmorillonite accelerated the curing rate and facilitated the reaction. The activation energy, reaction order and other kinetic parameters were calculated by Flynn-Wall-Ozawa, Kissinger, Crane methods.
2004, 21(2): 135-139
Abstract:
The title complex [Cu2(sphz)(DMF)3H2O]·(ClO4)2C22H32Cl2Cu2N6O14, where H2sphz is N,N'-salicylidene pyridine formylhydrazide, has been synthesized from H2sphz and copper perchlorate in a mixture of DMF and methanol. Crystal data of the complex were found:space group P21/c, a=1.08120(3)nm,b=2.57187(7)nm,c=1.1777(3)nm,β=104.1472(5)°,V=3.1757(2)nm3,Z=4,Dc=1.679Mg/m3,F(000)=1640,μ(MoKα)=1.582mm-1,R=0.0358 for 5 234 observed reflections(I≥2σ(I)), Rw=0.100 7, GOF=1.076. One copper(Ⅱ) ion in complex is coordinated with a pyridine nitrogen atom, a diazine nitrogen atom, two DMF oxygen atoms and a water oxygen atom, forming a distorted square pyramidal arrangement of N2O3. Another copper(Ⅱ) ion in complex is coordinated with a diazine nitrogen atom, a carbonyl oxygen atom, a phenoxy oxygen atom and a DMF oxygen atom, forming a distorted square arrangement of NO3. Every two molecules in the crystal are linked in pairs through the intermolecular hydrogen bonding. ν(C=O) and ν(C=N) are shifted to lower frequencies in IR spectra; π-π *charge transitions and d-π * charge-transitions are observed in their electronic spectra. The emission lines(λexc=310 nm) are shifted to higher frequencies in fluorescence spectra.
The title complex [Cu2(sphz)(DMF)3H2O]·(ClO4)2C22H32Cl2Cu2N6O14, where H2sphz is N,N'-salicylidene pyridine formylhydrazide, has been synthesized from H2sphz and copper perchlorate in a mixture of DMF and methanol. Crystal data of the complex were found:space group P21/c, a=1.08120(3)nm,b=2.57187(7)nm,c=1.1777(3)nm,β=104.1472(5)°,V=3.1757(2)nm3,Z=4,Dc=1.679Mg/m3,F(000)=1640,μ(MoKα)=1.582mm-1,R=0.0358 for 5 234 observed reflections(I≥2σ(I)), Rw=0.100 7, GOF=1.076. One copper(Ⅱ) ion in complex is coordinated with a pyridine nitrogen atom, a diazine nitrogen atom, two DMF oxygen atoms and a water oxygen atom, forming a distorted square pyramidal arrangement of N2O3. Another copper(Ⅱ) ion in complex is coordinated with a diazine nitrogen atom, a carbonyl oxygen atom, a phenoxy oxygen atom and a DMF oxygen atom, forming a distorted square arrangement of NO3. Every two molecules in the crystal are linked in pairs through the intermolecular hydrogen bonding. ν(C=O) and ν(C=N) are shifted to lower frequencies in IR spectra; π-π *charge transitions and d-π * charge-transitions are observed in their electronic spectra. The emission lines(λexc=310 nm) are shifted to higher frequencies in fluorescence spectra.
2004, 21(2): 140-143
Abstract:
The chiral separation of the racemic triadimefon, penconazole, hexaconazole and diniconazole was carried out on HPLC column using cellulose (3,5-dimethylphenylcarbamate) as a chiral stationary phase. The influences of the mobile phase composition and temperature on chiral separation were investigated and the chromatographic conditions were optimized. The results showed that the structure and concentration of alcohol in mobile phase strikingly affect the enantiomeric separation and retention. The ln α-1/T plot for racemic triadimefon is linear at 15~40℃. The ln α-1/T plots for racemic hexaconazole and diniconazole are broken lines. At 15~25℃ the chiral separation is controlled by enthalpy and at 25~40℃, it is enthopy controlled.
The chiral separation of the racemic triadimefon, penconazole, hexaconazole and diniconazole was carried out on HPLC column using cellulose (3,5-dimethylphenylcarbamate) as a chiral stationary phase. The influences of the mobile phase composition and temperature on chiral separation were investigated and the chromatographic conditions were optimized. The results showed that the structure and concentration of alcohol in mobile phase strikingly affect the enantiomeric separation and retention. The ln α-1/T plot for racemic triadimefon is linear at 15~40℃. The ln α-1/T plots for racemic hexaconazole and diniconazole are broken lines. At 15~25℃ the chiral separation is controlled by enthalpy and at 25~40℃, it is enthopy controlled.
2004, 21(2): 144-149
Abstract:
The lanthanum-nickel mixed oxides were prepared by chemical coprecipitation, sol-gel method and solid state reaction method. Their thermal stability and microstructure were analyzed by TG-DTA, XRD and TEM. The effects of preparation method, illumination, aging time and dosage of photocatalyst on the efficiency of photo degradation of reactive dyes were investigated. The results revealed that 90.0% reactive turquoise KGL(20 mg/L) could be degraded with 150 mg mixed oxides prepared by three methods after illumination for 120 min, and it was above 79.6% without illumination; above 83.1% reactive brilliant blue KNR(reactive dark GR and reactive brilliant red K2G) could be degraded with 100 mg mixed oxides prepared by chemical coprecipitation and solid state reaction methods after illumination for 20 min, and it was above 38.1% without illumination; the degradation degrees of KNR, GR, K2G were above 38.1% with 100 mg mixed oxides prepared by sol-gel method after illumination. The dyes didn't degradate by mixed oxides without illumination. The aged photocatalyst showed a higher photocatalytic activity.
The lanthanum-nickel mixed oxides were prepared by chemical coprecipitation, sol-gel method and solid state reaction method. Their thermal stability and microstructure were analyzed by TG-DTA, XRD and TEM. The effects of preparation method, illumination, aging time and dosage of photocatalyst on the efficiency of photo degradation of reactive dyes were investigated. The results revealed that 90.0% reactive turquoise KGL(20 mg/L) could be degraded with 150 mg mixed oxides prepared by three methods after illumination for 120 min, and it was above 79.6% without illumination; above 83.1% reactive brilliant blue KNR(reactive dark GR and reactive brilliant red K2G) could be degraded with 100 mg mixed oxides prepared by chemical coprecipitation and solid state reaction methods after illumination for 20 min, and it was above 38.1% without illumination; the degradation degrees of KNR, GR, K2G were above 38.1% with 100 mg mixed oxides prepared by sol-gel method after illumination. The dyes didn't degradate by mixed oxides without illumination. The aged photocatalyst showed a higher photocatalytic activity.
2004, 21(2): 150-153
Abstract:
A Schiff base, 1-phenyl-3-methyl-4-(α-furoyl)-5-pyrazolone-β-alanine(HL) and its UO22+, Cu(Ⅱ), Co(Ⅱ) and Fe(Ⅱ) complexes have been synthesized. The general formula of complexes were [UO2L2]·H2O, [CoL2]·3H2O and [FeL2]·2H2O, respectively, based on the elemental analysis and molar conductance results. They were characterized by IR, UV-visible, 1H NMR, 13C NMR, thermal analyses and magnetic moment measurement. The metal ions except UO22+ are six coordinated in the complexes. All of the complexes have high antibacterial activities against S.aureus, B.subtillis, E.coli, E.carotovora, and C.flaccumfaciens.
A Schiff base, 1-phenyl-3-methyl-4-(α-furoyl)-5-pyrazolone-β-alanine(HL) and its UO22+, Cu(Ⅱ), Co(Ⅱ) and Fe(Ⅱ) complexes have been synthesized. The general formula of complexes were [UO2L2]·H2O, [CoL2]·3H2O and [FeL2]·2H2O, respectively, based on the elemental analysis and molar conductance results. They were characterized by IR, UV-visible, 1H NMR, 13C NMR, thermal analyses and magnetic moment measurement. The metal ions except UO22+ are six coordinated in the complexes. All of the complexes have high antibacterial activities against S.aureus, B.subtillis, E.coli, E.carotovora, and C.flaccumfaciens.
2004, 21(2): 154-158
Abstract:
The effects of cerium oxide on the catalytic activity and the thermal stability of Pd/Al2O3 were investigated. It was found that the cerium oxide improved the performance of Pd/Al2O3 catalysts in removal of CO and C3H6 from simulated exhaust gas. The cerium oxide could widen the operation-window of oxidation reaction under reduction conditions (λ>1) due to its high oxygen storage-release capacity. Moreover, a great advantage of cerium oxide as a promoter is that it stabilizes the dispersion of Pd particles on the surface of Al2O3 during the sintering process. It may be due to the interaction of Pd with cerium oxide to form a Pdδ+ species which are more stable than Pd0 at high temperature.
The effects of cerium oxide on the catalytic activity and the thermal stability of Pd/Al2O3 were investigated. It was found that the cerium oxide improved the performance of Pd/Al2O3 catalysts in removal of CO and C3H6 from simulated exhaust gas. The cerium oxide could widen the operation-window of oxidation reaction under reduction conditions (λ>1) due to its high oxygen storage-release capacity. Moreover, a great advantage of cerium oxide as a promoter is that it stabilizes the dispersion of Pd particles on the surface of Al2O3 during the sintering process. It may be due to the interaction of Pd with cerium oxide to form a Pdδ+ species which are more stable than Pd0 at high temperature.
2004, 21(2): 159-163
Abstract:
The aggregation behavior of chitosan(CS) has been investigated with fluorescence probe technique. The fluorescence emission spectra and fluorescence polarization(p value) of 1,6-diphenyl hexatriene(DPH) in dilute aqueous solutions of CS were measured. Results indicate chitosan is able to self-aggregate and the aggregation could be obviously accelerated by the presence of sodium dodecylsulfate(SDS) in 0.1 mol/L acetic acid solution. The fluorescence emission of DPH was enhanced remarkably as the concentration of chitosan was 1.0 g/L. During the aggregation process, the structure of chitosan chains is transformed from stretched chains into coils and further transformed into intertwist coils.
The aggregation behavior of chitosan(CS) has been investigated with fluorescence probe technique. The fluorescence emission spectra and fluorescence polarization(p value) of 1,6-diphenyl hexatriene(DPH) in dilute aqueous solutions of CS were measured. Results indicate chitosan is able to self-aggregate and the aggregation could be obviously accelerated by the presence of sodium dodecylsulfate(SDS) in 0.1 mol/L acetic acid solution. The fluorescence emission of DPH was enhanced remarkably as the concentration of chitosan was 1.0 g/L. During the aggregation process, the structure of chitosan chains is transformed from stretched chains into coils and further transformed into intertwist coils.
2004, 21(2): 164-168
Abstract:
The catalyst system consisted of benzoyl chloride(BC), TiCl4 and a third additive is developed to initiate polymerization of isobutene(IB) and its copolymerization with styrene(St). Polyisobutene(PIB) and PIB-PS copolymers of high molecular weight and narrow molecular weight distribution were obtained whereas the high activity of BC could be controlled effectively. Based on the examination of the effects of the catalyst concentration, residual water and the third additive(triethyl amine(TEA)) on the reaction activity, the optimized condition is obtained as[BC]:=2.6 mmol/L and [TEA]/[BC]=1.0 for homopolymerization and n(TiCl4)/n(BC)=80 and[TEA]/[BC]=4.0 for copolymerization. The BC/TiCl4/TEA system is found to be the best optimal, it is characteristic of being insensitive to water. PIB with MWD=1.5 and P(IB-co-St) with MWD=2.0 were obtained(only single peak occurred in their GPC curves).
The catalyst system consisted of benzoyl chloride(BC), TiCl4 and a third additive is developed to initiate polymerization of isobutene(IB) and its copolymerization with styrene(St). Polyisobutene(PIB) and PIB-PS copolymers of high molecular weight and narrow molecular weight distribution were obtained whereas the high activity of BC could be controlled effectively. Based on the examination of the effects of the catalyst concentration, residual water and the third additive(triethyl amine(TEA)) on the reaction activity, the optimized condition is obtained as[BC]:=2.6 mmol/L and [TEA]/[BC]=1.0 for homopolymerization and n(TiCl4)/n(BC)=80 and[TEA]/[BC]=4.0 for copolymerization. The BC/TiCl4/TEA system is found to be the best optimal, it is characteristic of being insensitive to water. PIB with MWD=1.5 and P(IB-co-St) with MWD=2.0 were obtained(only single peak occurred in their GPC curves).
2004, 21(2): 169-173
Abstract:
The high organosilicone content(m(polysiloxane):m(MMA)=7:6) polysiloxane/acrylates copo-lymer latex with core-shell structure was prepared by seeding emulsion polymerization from methyl methacrylate(MMA) with polysiloxane latex as a seed. The effects of feeding mode of MMA and preparation conditions(temperature, concentrations of initiator, reaction time) on the kinetics of polymerization, the average particle size and its distribution, and the morphology of the obtained particles were studied. The composite emulsifier of sodium lauryl sulphate and OP-10 appeared to be a preferable emulsifier system in the preparation of polysiloxane/MMA copolymer latex with the excellent storage. The increase of polymerization temperature, concentrations of initiator and emulsifier increases the polymerization rate. Higher concentration of emulsifier gave smaller size. In comparison with single polymerization, the seeding polymerization process with MMA was more preferable for preparing a stable copolymer latex with smaller particle size and narrower distribution. The TEM photos show that the composite particles have clear core/shell structure, but the particles obtained by single polymerization have irregular shape.
The high organosilicone content(m(polysiloxane):m(MMA)=7:6) polysiloxane/acrylates copo-lymer latex with core-shell structure was prepared by seeding emulsion polymerization from methyl methacrylate(MMA) with polysiloxane latex as a seed. The effects of feeding mode of MMA and preparation conditions(temperature, concentrations of initiator, reaction time) on the kinetics of polymerization, the average particle size and its distribution, and the morphology of the obtained particles were studied. The composite emulsifier of sodium lauryl sulphate and OP-10 appeared to be a preferable emulsifier system in the preparation of polysiloxane/MMA copolymer latex with the excellent storage. The increase of polymerization temperature, concentrations of initiator and emulsifier increases the polymerization rate. Higher concentration of emulsifier gave smaller size. In comparison with single polymerization, the seeding polymerization process with MMA was more preferable for preparing a stable copolymer latex with smaller particle size and narrower distribution. The TEM photos show that the composite particles have clear core/shell structure, but the particles obtained by single polymerization have irregular shape.
2004, 21(2): 174-177
Abstract:
The chlorination of arylalkylketone has been carried out with cupric(Ⅱ) chloride in refluxing ethanol. For propiophenone, 3-chloropropiophenone and 6-methoxy-2-propionylnaphthalene the main products were α-monochlorinated compounds(2) and for 6-methoxy-2-acetylnaphthalene and 4-methoxy-acetophenone, α,α-dichlorinated products were formed. The structures of chlorinated products were characterized by 1H NMR and MS spectral measurements.
The chlorination of arylalkylketone has been carried out with cupric(Ⅱ) chloride in refluxing ethanol. For propiophenone, 3-chloropropiophenone and 6-methoxy-2-propionylnaphthalene the main products were α-monochlorinated compounds(2) and for 6-methoxy-2-acetylnaphthalene and 4-methoxy-acetophenone, α,α-dichlorinated products were formed. The structures of chlorinated products were characterized by 1H NMR and MS spectral measurements.
Sythesis, Electrochemical and Magnetic Properties of Cu(Ⅱ)-VO(Ⅱ) Heterobinuclear Schiff Base Complex
2004, 21(2): 178-181
Abstract:
Heterobinuclear complex CuVOTS·MeOH, where TS is the schiff base N,N'-bis(3-carboxylsalicylidene)trimethylenediamine, was synthesized and characterized by elemental analysis, IR and UV-vis spectra. The electrochemical property of the complex was examined by cyclic voltammetry in DMSO. The results show that the coordination of the second metal ion could increase the stability of the inner copper(Ⅱ) ion. The temperature dependence of the magnetic susceptibility of Cu(Ⅱ)-VO(Ⅱ) over the range 4~300 K gave the exchange integral J=-1.631 2 cm-1, which indicates the presence of weak antiferromagnetic interaction between the internal Cu2+ ion and the outer VO2+ ion in the heterobinuclear complex.
Heterobinuclear complex CuVOTS·MeOH, where TS is the schiff base N,N'-bis(3-carboxylsalicylidene)trimethylenediamine, was synthesized and characterized by elemental analysis, IR and UV-vis spectra. The electrochemical property of the complex was examined by cyclic voltammetry in DMSO. The results show that the coordination of the second metal ion could increase the stability of the inner copper(Ⅱ) ion. The temperature dependence of the magnetic susceptibility of Cu(Ⅱ)-VO(Ⅱ) over the range 4~300 K gave the exchange integral J=-1.631 2 cm-1, which indicates the presence of weak antiferromagnetic interaction between the internal Cu2+ ion and the outer VO2+ ion in the heterobinuclear complex.
2004, 21(2): 182-186
Abstract:
The poly(siloxane-acrylate) microemulsions were synthesized using K2S2O8 as initiator and copolymer nanoparticles were obtained. The effects of polymerization methods, the TS/SDS mass ratio and the content of siloxane on the polymerization and properties of the microemulsion were investigated. The best results were obtained by seeding semi-continuous emulsion polymerization, by which the poly(siloxane-acrylate) microemulsion with average particle size of 46.1 nm could be obtained with low surfactant concentration(2.5%) and relatively high copolymer content(30%).
The poly(siloxane-acrylate) microemulsions were synthesized using K2S2O8 as initiator and copolymer nanoparticles were obtained. The effects of polymerization methods, the TS/SDS mass ratio and the content of siloxane on the polymerization and properties of the microemulsion were investigated. The best results were obtained by seeding semi-continuous emulsion polymerization, by which the poly(siloxane-acrylate) microemulsion with average particle size of 46.1 nm could be obtained with low surfactant concentration(2.5%) and relatively high copolymer content(30%).
2004, 21(2): 187-191
Abstract:
The kinetics of calcium carbonate scale formation has been studied based on the conductivity measurement including the rate of the nucleus formation and crystal growth as well as the influences of temperature and the scale inhibitors. The reaction constant and activation energy in the presence of scale inhibitors at different temperatures have been calculated. It shows that the nucleus formation and crystal growth can be expressed as a first order reaction. Temperature and scale inhibitor mainly influence the rates of nuclei formation. The higher temperature, the greater the reaction rate. In some scope of supersaturation, the induction period of calcium carbonate can be prolonged and the rate of calcium carbonate can be reduced by adding a certain concentration of scale inhibitor. But the reaction order remained unchanged. Once the nucleus has formed in the supersaturation solution, the crystal growths more easily. That is, the condition of crystal growth is the presence of a nucleus, the temperature and scale inhibitors have little effect on crystal growth.
The kinetics of calcium carbonate scale formation has been studied based on the conductivity measurement including the rate of the nucleus formation and crystal growth as well as the influences of temperature and the scale inhibitors. The reaction constant and activation energy in the presence of scale inhibitors at different temperatures have been calculated. It shows that the nucleus formation and crystal growth can be expressed as a first order reaction. Temperature and scale inhibitor mainly influence the rates of nuclei formation. The higher temperature, the greater the reaction rate. In some scope of supersaturation, the induction period of calcium carbonate can be prolonged and the rate of calcium carbonate can be reduced by adding a certain concentration of scale inhibitor. But the reaction order remained unchanged. Once the nucleus has formed in the supersaturation solution, the crystal growths more easily. That is, the condition of crystal growth is the presence of a nucleus, the temperature and scale inhibitors have little effect on crystal growth.
2004, 21(2): 192-196
Abstract:
5-Fluorouracil(5-Fu) chitosan(CS) microspheres were prepared in emulsion by using glutaradelhyde as cross-linking agent, span-80 and magnesium stearate mixture as emulsifer and vacuum-pump oil-paraffin oil mixture as oil phase. 5-Fu encapsulated capacity was of 43.6%~84.8%, one to several times higher than that reported in literatures(about 15.1%). Drug releasing property of 5-Fu/CS capsules was studied in the phosphate buffer(pH=7.4) and citrate buffer(pH=3.9) solutions. The results showed that m(5-Fu)/m(CS), amount of cross-linking agent and the pH value of media all affected the releasing of 5-Fu from microspheres. The drug releasing rate was found decreased with m(5-Fu)/m(CS) and increased with n(CHO)/n(NH2). The drug releasing performance was better in the acid media than in the alkali one. The IR results indicated there was a strong molecular interaction between 5-Fu and chitosan. SEM images show the 5-Fu-CS microspheres are spherical shape with diameters ranged from 1~5 μm.
5-Fluorouracil(5-Fu) chitosan(CS) microspheres were prepared in emulsion by using glutaradelhyde as cross-linking agent, span-80 and magnesium stearate mixture as emulsifer and vacuum-pump oil-paraffin oil mixture as oil phase. 5-Fu encapsulated capacity was of 43.6%~84.8%, one to several times higher than that reported in literatures(about 15.1%). Drug releasing property of 5-Fu/CS capsules was studied in the phosphate buffer(pH=7.4) and citrate buffer(pH=3.9) solutions. The results showed that m(5-Fu)/m(CS), amount of cross-linking agent and the pH value of media all affected the releasing of 5-Fu from microspheres. The drug releasing rate was found decreased with m(5-Fu)/m(CS) and increased with n(CHO)/n(NH2). The drug releasing performance was better in the acid media than in the alkali one. The IR results indicated there was a strong molecular interaction between 5-Fu and chitosan. SEM images show the 5-Fu-CS microspheres are spherical shape with diameters ranged from 1~5 μm.
2004, 21(2): 197-199
Abstract:
Poly(styrene-acrylic acid) nanoparticles were prepared by emulsifier-free emulsion polymerization under ultrasonic irradiation and characterized by IR and TEM. The results show that the average diameter of the nanoparticles is 9 nm. The resonance light scattering peak was at 340 nm and it was greatly enhanced by protein. The nanoparticles are stable, water-soluble and bioactivity. A high sensitive RLS probe for protein determination was proposed.
Poly(styrene-acrylic acid) nanoparticles were prepared by emulsifier-free emulsion polymerization under ultrasonic irradiation and characterized by IR and TEM. The results show that the average diameter of the nanoparticles is 9 nm. The resonance light scattering peak was at 340 nm and it was greatly enhanced by protein. The nanoparticles are stable, water-soluble and bioactivity. A high sensitive RLS probe for protein determination was proposed.
2004, 21(2): 200-202
Abstract:
Paraffin microcapsules with urea-formaldehyde polymer skin are prepared by in-situ polymerization of urea-formaldehyde prepolymer. It is found that the pH value of the aqueous solution, addition of NaCl and temperature affect the developing rate of microcapsules, and the most important appears pH value. The thermal properties of the microcapsules are explored by differential scanning calorimetry. The optimum conditions are:pH value 1.5, temperature 333.15~363.15 K, mass fraction of NaCl about 10%. The thermal analysis results show that the endothermic ability between 296.26 K and 308.15 K amounts to 9.11 J/g when the microcapsules undergo solid-liquid phase change at 300.53 K, the mean fusion heat of the microcapsule is 1.20 J/(g·K).
Paraffin microcapsules with urea-formaldehyde polymer skin are prepared by in-situ polymerization of urea-formaldehyde prepolymer. It is found that the pH value of the aqueous solution, addition of NaCl and temperature affect the developing rate of microcapsules, and the most important appears pH value. The thermal properties of the microcapsules are explored by differential scanning calorimetry. The optimum conditions are:pH value 1.5, temperature 333.15~363.15 K, mass fraction of NaCl about 10%. The thermal analysis results show that the endothermic ability between 296.26 K and 308.15 K amounts to 9.11 J/g when the microcapsules undergo solid-liquid phase change at 300.53 K, the mean fusion heat of the microcapsule is 1.20 J/(g·K).
2004, 21(2): 203-205
Abstract:
The experimental results indicate that aluminum phosphate(AlPO4) can be prepared from aluminum chloride and ammonium dihydric phosphate at 180℃ and 2 h by solid-state synthesis in the presence of organic ammonium as template. The compositions and the structures of the AlPO4 and related compounds were characterized by chemical analysis, ICPS, FT-IR and XRD. The absorption property of AlPO4 to Cr(Ⅵ) ion were also examined.
The experimental results indicate that aluminum phosphate(AlPO4) can be prepared from aluminum chloride and ammonium dihydric phosphate at 180℃ and 2 h by solid-state synthesis in the presence of organic ammonium as template. The compositions and the structures of the AlPO4 and related compounds were characterized by chemical analysis, ICPS, FT-IR and XRD. The absorption property of AlPO4 to Cr(Ⅵ) ion were also examined.
2004, 21(2): 206-208
Abstract:
Three polyamidoamine(PAMAM) dendrimers have been synthesized by divergence method with ethylenediamine as core. The surface tensions of aqueous solution of different generation PAMAM were determined by traditional surfactant method. The results showed that the whole PAMAM doesn't have surface acti-vity and the half PAMAM have certain surface activity. Their critical micelle concentrations(CMC) were obtained from surface tension curves, and the hydrophile-lipophile balance number(HLB), saturated adsorption capacity, molecular cross section area and molecular diameter were calculated. The results revealed that the molecular diameter of 0.5G, 1.5G and 2.5G PAMAM were 0.743, 0.998 and 1.371 nanometer, respe-ctively. The dendrimer obtained was also proved to be of nanometer order.
Three polyamidoamine(PAMAM) dendrimers have been synthesized by divergence method with ethylenediamine as core. The surface tensions of aqueous solution of different generation PAMAM were determined by traditional surfactant method. The results showed that the whole PAMAM doesn't have surface acti-vity and the half PAMAM have certain surface activity. Their critical micelle concentrations(CMC) were obtained from surface tension curves, and the hydrophile-lipophile balance number(HLB), saturated adsorption capacity, molecular cross section area and molecular diameter were calculated. The results revealed that the molecular diameter of 0.5G, 1.5G and 2.5G PAMAM were 0.743, 0.998 and 1.371 nanometer, respe-ctively. The dendrimer obtained was also proved to be of nanometer order.
2004, 21(2): 209-211
Abstract:
The direct electrolytic oxidation of p-tert-butyl toluene in a mixture of sodium fluoborate, acetic acid and methanol using carbon rod as electrode has been studied. The main electrolytic oxidation products, p-tert-butylbenzaldehyde,p-tert-butylbenzyl methyl ether, p-tert-butyl benzaldehyde dimethyl acetal, and methyl p-tert-butylbenzoate were separated and identified by GC/MS. The relation between the oxidation pro-duct and the oxidation time in electrolytic oxidation was examined. The total yield of p-tert-butylbenzaldehyde and p-tert-butyl benzaldehyde dimethyl acetal was over 88% in period of 30 h oxidation.
The direct electrolytic oxidation of p-tert-butyl toluene in a mixture of sodium fluoborate, acetic acid and methanol using carbon rod as electrode has been studied. The main electrolytic oxidation products, p-tert-butylbenzaldehyde,p-tert-butylbenzyl methyl ether, p-tert-butyl benzaldehyde dimethyl acetal, and methyl p-tert-butylbenzoate were separated and identified by GC/MS. The relation between the oxidation pro-duct and the oxidation time in electrolytic oxidation was examined. The total yield of p-tert-butylbenzaldehyde and p-tert-butyl benzaldehyde dimethyl acetal was over 88% in period of 30 h oxidation.
2004, 21(2): 212-214
Abstract:
Poly(aluminum chloride)(PAC) solutions of different basicity were prepared from pure aluminum foil and hydrochloric acid. Aluminum species were investigated by 27Al NMR spectroscopy and the tridecameric polycation Al13 was detected. With the increase of PAC's basicity, the molar ratio of Al13 to Alm in PAC increases. The jar tests with kaolin water and water from Huangpu River at the same PACs dosage showed that the more basicity and content of Al13, the more effective the coagulation effect on water with middle-high turbidity, while only less effect of the basicity was observed on water with low turbidity.
Poly(aluminum chloride)(PAC) solutions of different basicity were prepared from pure aluminum foil and hydrochloric acid. Aluminum species were investigated by 27Al NMR spectroscopy and the tridecameric polycation Al13 was detected. With the increase of PAC's basicity, the molar ratio of Al13 to Alm in PAC increases. The jar tests with kaolin water and water from Huangpu River at the same PACs dosage showed that the more basicity and content of Al13, the more effective the coagulation effect on water with middle-high turbidity, while only less effect of the basicity was observed on water with low turbidity.
2004, 21(2): 215-216
Abstract:
Tetrahydroquinoline was prepared by direct electrolysis-reduction quinolines in yield 43.9%. N-acetyl-tetrahydroquinoline was synthesized by acetylation of tetrahydroquinoline with acetic oxide. The synthetic procedures have advantages of simplicity in equipment and mild reaction conditions.
Tetrahydroquinoline was prepared by direct electrolysis-reduction quinolines in yield 43.9%. N-acetyl-tetrahydroquinoline was synthesized by acetylation of tetrahydroquinoline with acetic oxide. The synthetic procedures have advantages of simplicity in equipment and mild reaction conditions.
