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2006 Volume 23 Issue 1
2006, 23(1): 1-6
Abstract:
Since the discovery of silicate and aluminumsilicate ordered materials in the early 1900s, they display a periodic array of mesopores of tailored and narrowly distributed size, have attracted the attention of many research groups due to their special properties.Much work has been devoted to the studies of the synthesis, application of such materials and siliceous ordered mesoporous materials, they have been well-investigated and covered by several excellent reviews.However, less work has been done for non-siliceous mesoporous materials and mesoporous composites, although they could have more interesting properties and wide range applications in the areas such as optics, electricity, magnetics, catalysis and sensors.The latest progress in the study of non-siliceous mesoporous materials, mesoporous composites is reviewed and the basic concepts, mechanisms, properties and applications are introduced.Based on the existing problems in this field, the development trend, application and research directions are discussed.
Since the discovery of silicate and aluminumsilicate ordered materials in the early 1900s, they display a periodic array of mesopores of tailored and narrowly distributed size, have attracted the attention of many research groups due to their special properties.Much work has been devoted to the studies of the synthesis, application of such materials and siliceous ordered mesoporous materials, they have been well-investigated and covered by several excellent reviews.However, less work has been done for non-siliceous mesoporous materials and mesoporous composites, although they could have more interesting properties and wide range applications in the areas such as optics, electricity, magnetics, catalysis and sensors.The latest progress in the study of non-siliceous mesoporous materials, mesoporous composites is reviewed and the basic concepts, mechanisms, properties and applications are introduced.Based on the existing problems in this field, the development trend, application and research directions are discussed.
2006, 23(1): 7-11
Abstract:
The mono-armed CdS nanorods with a few multi-armed nanorods were synthesized through a reaction of CdCl2 with thioacetamide(TAA) under basic conditions at room temperature in the presence of the rod-shaped micellar template of cetyltrimethylammonium bromide (CTAB).The length of the arms can be controlled via adjusting the amount of cyclohexane.To some extent, more cyclohexane results in longer nanorods.The nanorods can be prepared with a diameter of 26~48 nm and a length of 240~1 200 nm through this approach.The resulting nanorods were characterized by wide-angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray photoelectron spectroscopy(XPS).
The mono-armed CdS nanorods with a few multi-armed nanorods were synthesized through a reaction of CdCl2 with thioacetamide(TAA) under basic conditions at room temperature in the presence of the rod-shaped micellar template of cetyltrimethylammonium bromide (CTAB).The length of the arms can be controlled via adjusting the amount of cyclohexane.To some extent, more cyclohexane results in longer nanorods.The nanorods can be prepared with a diameter of 26~48 nm and a length of 240~1 200 nm through this approach.The resulting nanorods were characterized by wide-angle X-ray diffraction (WAXD), transmission electron microscopy (TEM), selected area electron diffraction (SAED) and X-ray photoelectron spectroscopy(XPS).
2006, 23(1): 12-17
Abstract:
A series of novel azo type crown ether liquid crystallines was synthesized from intermediates 4'-n-alkoxylbiphenyl-4-carboxylic acids and cis (trans)-4, 4'-bis (4-hydroxyphenylazo) dibenzo-18-crown-6 in yields of 91.7%~95.8% and their structures and properties were characterized by means of elemental analysis,1H NMR, UV-vis, IR, MALDI-TOF-MS, DSC, polarizing optical microscope with a heating stage and X-ray diffraction techniques.It was found that the end products 4Ⅰ and 4Ⅱ formed liquid crystalline phases when heated to their melting points.In their liquid crystalline state, the typical smectic phase and nemetic phase textures(4ⅡD) can be observed.For compounds 4Ⅰ and 4Ⅱ, both melting poinT(Tm) and isotropization temperature (Ti) were decreased with the increase of the carbon numbers in the end alkoxy groups.However, the temperature range of liquid crystal phase was relatively wide.
A series of novel azo type crown ether liquid crystallines was synthesized from intermediates 4'-n-alkoxylbiphenyl-4-carboxylic acids and cis (trans)-4, 4'-bis (4-hydroxyphenylazo) dibenzo-18-crown-6 in yields of 91.7%~95.8% and their structures and properties were characterized by means of elemental analysis,1H NMR, UV-vis, IR, MALDI-TOF-MS, DSC, polarizing optical microscope with a heating stage and X-ray diffraction techniques.It was found that the end products 4Ⅰ and 4Ⅱ formed liquid crystalline phases when heated to their melting points.In their liquid crystalline state, the typical smectic phase and nemetic phase textures(4ⅡD) can be observed.For compounds 4Ⅰ and 4Ⅱ, both melting poinT(Tm) and isotropization temperature (Ti) were decreased with the increase of the carbon numbers in the end alkoxy groups.However, the temperature range of liquid crystal phase was relatively wide.
2006, 23(1): 18-21
Abstract:
A novel organic-inorganic complex, (TMB)3PMA was synthesized.There was an electron transfer between TMB and heteropoly anion, PMA.The UV irradiation could promote the oxidation of TMB, in turn, promotes the electron transfer within the (TMB)3PMA molecule.After (TMB)3PMA was doped into PVA to form a thin film, the photochromism of (TMB)3PMA became stable because the conductive and enclosed action of the hydrogen bonds of PVA.The electrochemical reactions of the (TMB)3PMA/PVA thin film at the Au electrode were quasi-reversible.(TMB)3PMA/PVA thin film modified electrode displayed electrocatalytic activity for the reduction of IO3-.
A novel organic-inorganic complex, (TMB)3PMA was synthesized.There was an electron transfer between TMB and heteropoly anion, PMA.The UV irradiation could promote the oxidation of TMB, in turn, promotes the electron transfer within the (TMB)3PMA molecule.After (TMB)3PMA was doped into PVA to form a thin film, the photochromism of (TMB)3PMA became stable because the conductive and enclosed action of the hydrogen bonds of PVA.The electrochemical reactions of the (TMB)3PMA/PVA thin film at the Au electrode were quasi-reversible.(TMB)3PMA/PVA thin film modified electrode displayed electrocatalytic activity for the reduction of IO3-.
2006, 23(1): 22-25
Abstract:
New biopolymer poly(3-hydroxybutylate-co-hydroxyvalerate) (PHBV) films were treated with oxygen plasma and hydrolyzed under alkaline condition to render them hydrophilicity and cell affinity.The surface composition and elemental chemical state of PHBV films after modification were characterized via XPS, while surface morphologies were observed with SEM, and the growth of bone marrow stromal cells (BMSCs) on the films were also investigated.It was shown that oxygen contents of PHBV films were increased by 5.3% and 2.5%, water contact angles were reduced by 36° and 16.7° respectively after oxygen plasma treatment and hydrolysis, the results suggested the improvement of surface hydrophilicity.After oxygen plasma treatment, 1.5% C-O bonds and 3.5% C-C bonds cleft and carboxyl bonds were generated, while under alkaline condition the ester bonds in PHBV hydrolyzed to form more hydroxyl and carboxyl bonds.Modified PHBV films were favourable for cell growth, especially the films after oxygen plasma treatment.The results have laid the foundation for further surface modification and preparation of three-dimensional PHBV scaffold with good cell affinity.
New biopolymer poly(3-hydroxybutylate-co-hydroxyvalerate) (PHBV) films were treated with oxygen plasma and hydrolyzed under alkaline condition to render them hydrophilicity and cell affinity.The surface composition and elemental chemical state of PHBV films after modification were characterized via XPS, while surface morphologies were observed with SEM, and the growth of bone marrow stromal cells (BMSCs) on the films were also investigated.It was shown that oxygen contents of PHBV films were increased by 5.3% and 2.5%, water contact angles were reduced by 36° and 16.7° respectively after oxygen plasma treatment and hydrolysis, the results suggested the improvement of surface hydrophilicity.After oxygen plasma treatment, 1.5% C-O bonds and 3.5% C-C bonds cleft and carboxyl bonds were generated, while under alkaline condition the ester bonds in PHBV hydrolyzed to form more hydroxyl and carboxyl bonds.Modified PHBV films were favourable for cell growth, especially the films after oxygen plasma treatment.The results have laid the foundation for further surface modification and preparation of three-dimensional PHBV scaffold with good cell affinity.
2006, 23(1): 26-29
Abstract:
A Dawson structure heteropoly complex K10Na2H2P2W16O60·18H2O was prepared and used to catalyze the synthesis of adipic acid from cyclohexanone, oxidized by 30% hydrogen peroxide without any solvent or phase transfer agent.The results show that the catalyst had a high activity.The influences of reaction conditions such as ligands, amount of catalyst, ratio of reactants, reaction time were studied.Optimal reaction conditions were that n(tungsten):n(sulfosalicylic acid):n(cyclohexanone):n(hydrogen peroxide) was 2:1:100:400, and reflux temperature 98℃, the time 5 h.The isolated yield of adipic acid could reach 76.7%.
A Dawson structure heteropoly complex K10Na2H2P2W16O60·18H2O was prepared and used to catalyze the synthesis of adipic acid from cyclohexanone, oxidized by 30% hydrogen peroxide without any solvent or phase transfer agent.The results show that the catalyst had a high activity.The influences of reaction conditions such as ligands, amount of catalyst, ratio of reactants, reaction time were studied.Optimal reaction conditions were that n(tungsten):n(sulfosalicylic acid):n(cyclohexanone):n(hydrogen peroxide) was 2:1:100:400, and reflux temperature 98℃, the time 5 h.The isolated yield of adipic acid could reach 76.7%.
2006, 23(1): 30-33
Abstract:
Photochemical reaction of C60 with iminodiacetic ester (NH(CH2COOR)2 (R=Me,Et,t-Bu) produces fulleropyrrolidine derivative 2 in a 55%~36% yield (based on consumed C60).The reaction activity is correlated to the steric hindrance of R groups.The reaction rate decreases, in the order of from Me to t-Bu (R=Me >Et >t-Bu).Fulleropyrrolidine derivative 2(R=Me) were hydrolyzed with NaH and methanol in toluene, and then acidified with HCl to result in the corresponding fulleropyrrolidine dicarboxylic acid 3 in a 65% yield (relative to fulleropyrrolidine derivative 2).C60 derivatives 2 and 3 were structurally characterized by 1H NMR, 13C NMR, IR and elemental analysis.A chemiluminescence technique was applied to study the effects of their scavenging superoxide radicals (O2-·) generated by pyrogallol autoxidation.The results show fulleropyrrolidine dicarboxylic acid 3 has the scavenging activity and the efficiency is dependent on the concentration.At 3.0×10-4 mol/L, fulleropyrrolidine dicarboxylic acid 3 showed a radical scavenging efficiency of approximate 70%.Finally the influence of structure factor on the scavenging activity was discussed.The results show that the monoadduct of C60, owing to keeping almost intact double bonds in C60, moiety, has an obvious scavenging activity for superoxide radicals (O2-·).
Photochemical reaction of C60 with iminodiacetic ester (NH(CH2COOR)2 (R=Me,Et,t-Bu) produces fulleropyrrolidine derivative 2 in a 55%~36% yield (based on consumed C60).The reaction activity is correlated to the steric hindrance of R groups.The reaction rate decreases, in the order of from Me to t-Bu (R=Me >Et >t-Bu).Fulleropyrrolidine derivative 2(R=Me) were hydrolyzed with NaH and methanol in toluene, and then acidified with HCl to result in the corresponding fulleropyrrolidine dicarboxylic acid 3 in a 65% yield (relative to fulleropyrrolidine derivative 2).C60 derivatives 2 and 3 were structurally characterized by 1H NMR, 13C NMR, IR and elemental analysis.A chemiluminescence technique was applied to study the effects of their scavenging superoxide radicals (O2-·) generated by pyrogallol autoxidation.The results show fulleropyrrolidine dicarboxylic acid 3 has the scavenging activity and the efficiency is dependent on the concentration.At 3.0×10-4 mol/L, fulleropyrrolidine dicarboxylic acid 3 showed a radical scavenging efficiency of approximate 70%.Finally the influence of structure factor on the scavenging activity was discussed.The results show that the monoadduct of C60, owing to keeping almost intact double bonds in C60, moiety, has an obvious scavenging activity for superoxide radicals (O2-·).
2006, 23(1): 34-37
Abstract:
The heterogeneous degradation of chitosan with hydrogen peroxide under the catalysis of phospho-tungstic acid was studied.The eEEeFts of FonFentration of hydrogen peroxide, reaFtion and time, dosage of catalyst on the degradation are discussed by means of orthogonal tests.The mechanism of the degradation is also discussed.The experimental results show that chitosan can be effectively degraded with hydrogen peroxide under the catalysis of phosphotungstic acid.The optimum reaction conditions are as follows:hydrogen peroxide is 2.7 mol/L,the mass ratio of phosphotungstic acid to chitosan is 0.01, reaction time is 20 min, reaction temperature is 90℃.Water-Soluble chitosan with average molecular weight 12 000 was produced under the experiment condition.
The heterogeneous degradation of chitosan with hydrogen peroxide under the catalysis of phospho-tungstic acid was studied.The eEEeFts of FonFentration of hydrogen peroxide, reaFtion and time, dosage of catalyst on the degradation are discussed by means of orthogonal tests.The mechanism of the degradation is also discussed.The experimental results show that chitosan can be effectively degraded with hydrogen peroxide under the catalysis of phosphotungstic acid.The optimum reaction conditions are as follows:hydrogen peroxide is 2.7 mol/L,the mass ratio of phosphotungstic acid to chitosan is 0.01, reaction time is 20 min, reaction temperature is 90℃.Water-Soluble chitosan with average molecular weight 12 000 was produced under the experiment condition.
2006, 23(1): 38-41
Abstract:
Grafting co-polymerization of chitosan and acrylamide with inexpensive ammonium persulfate as initiator was studied and the property of flocculating of the co-polymerization product was also studied.Experimental results show that the grafting percentage is 133.40%, viscosity is highter than 100 000 mPa·s trans-mittance of treating simulated waste water is 99% and the property of flocculating is the best when the concentration of initiator is 3 mmol/L, the mass ratio of chitosan to acrylamide is 2:1, reaction temperature is 30℃, reaction time is 3~3.5 h and the volume fraction of glacial acetic acid is 1.5%.
Grafting co-polymerization of chitosan and acrylamide with inexpensive ammonium persulfate as initiator was studied and the property of flocculating of the co-polymerization product was also studied.Experimental results show that the grafting percentage is 133.40%, viscosity is highter than 100 000 mPa·s trans-mittance of treating simulated waste water is 99% and the property of flocculating is the best when the concentration of initiator is 3 mmol/L, the mass ratio of chitosan to acrylamide is 2:1, reaction temperature is 30℃, reaction time is 3~3.5 h and the volume fraction of glacial acetic acid is 1.5%.
2006, 23(1): 42-47
Abstract:
A chiral heterogeneous hydrogenation catalyst (M-CS-SiO2) was prepared by supporting transition metal on natural macromolecular biopolymer of chitosan covering on silicon dioxide, and characterized with elemental analysis, FT-IR and XRD.The catalytic performance of the chiral catalyst was investigated for the asymmetric transfer hydrogenation of acetophenone to R(S)-1-phenyl ethanol in ambient condition.The results indicate that among the chiral M-CS-SiO2(M=Pd, Pt, Rh and Ru) catalysts prepared, the Pd-CS-SiO2 catalyst shows the best catalytic activity and enantioselectivity to R-1-phenyl ethanol, and the palladium precursor affects its catalytic performance very little.In the asymmetric transfer hydrogenation of acetophenone catalyzed with Pd-CS-SiO2,the catalytic activity and the enantioselectivity are greatly influenced by the sort of H-donor used and reaction temperature.Ammonium formate and sodium formate are the suitable hydrogen donors.If there is some water in the solvent, the asymmetric transfer hydrogenation of acetophenone will be deteriorated as ammonium formate is used as H-donor;when sodium formate is used as H-donor, the presence of 5% water in the solvent can increase 8.4% enantiomeric excess.When ammonium formate was used as hydrogen donor and the asymmetric transfer hydrogenation of acetophenone was performed at 80℃, the enantiomeric excess of R-1-phenylethanol reached to 69%.
A chiral heterogeneous hydrogenation catalyst (M-CS-SiO2) was prepared by supporting transition metal on natural macromolecular biopolymer of chitosan covering on silicon dioxide, and characterized with elemental analysis, FT-IR and XRD.The catalytic performance of the chiral catalyst was investigated for the asymmetric transfer hydrogenation of acetophenone to R(S)-1-phenyl ethanol in ambient condition.The results indicate that among the chiral M-CS-SiO2(M=Pd, Pt, Rh and Ru) catalysts prepared, the Pd-CS-SiO2 catalyst shows the best catalytic activity and enantioselectivity to R-1-phenyl ethanol, and the palladium precursor affects its catalytic performance very little.In the asymmetric transfer hydrogenation of acetophenone catalyzed with Pd-CS-SiO2,the catalytic activity and the enantioselectivity are greatly influenced by the sort of H-donor used and reaction temperature.Ammonium formate and sodium formate are the suitable hydrogen donors.If there is some water in the solvent, the asymmetric transfer hydrogenation of acetophenone will be deteriorated as ammonium formate is used as H-donor;when sodium formate is used as H-donor, the presence of 5% water in the solvent can increase 8.4% enantiomeric excess.When ammonium formate was used as hydrogen donor and the asymmetric transfer hydrogenation of acetophenone was performed at 80℃, the enantiomeric excess of R-1-phenylethanol reached to 69%.
2006, 23(1): 48-53
Abstract:
In the investigations of electrochemical reduction of nitrobenzene to p-Aminophenol at the Monel alloy electrode, it was found that the yield gradually decreased with the increase of the service time of the Monel alloy electrode.At the initial stage of reaction, the yield of p-Aminophenol at the Monel electrode was 75.2%, which was close to that at the Cu-Hg electrode.Within 500 h service time, the yield could be maintained above 70%.However, the yield decreased greatly to 63.1% after 800 h service, which was close to that at the Cu electrode.In order to figure out the reasons of the decrease, the Monel alloy electrodes before and after service were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and the electrochemical method.The results from the XRD indicate that the surface unit cell composition of the Monel alloy electrode had significant variations after 800 h service, compared with that of the electrode before service.The results from the SEM and EDS show that the changes of the surface composition and state of the Monel alloy electrode were caused by the surface element enrichment of Cu, they were the main reasons for the deterioration of electrocatalytic properties of the electrode in the electrochemical reduction of nitrobenzene.The results from steady-state polarization confirm the conclusion further.
In the investigations of electrochemical reduction of nitrobenzene to p-Aminophenol at the Monel alloy electrode, it was found that the yield gradually decreased with the increase of the service time of the Monel alloy electrode.At the initial stage of reaction, the yield of p-Aminophenol at the Monel electrode was 75.2%, which was close to that at the Cu-Hg electrode.Within 500 h service time, the yield could be maintained above 70%.However, the yield decreased greatly to 63.1% after 800 h service, which was close to that at the Cu electrode.In order to figure out the reasons of the decrease, the Monel alloy electrodes before and after service were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and the electrochemical method.The results from the XRD indicate that the surface unit cell composition of the Monel alloy electrode had significant variations after 800 h service, compared with that of the electrode before service.The results from the SEM and EDS show that the changes of the surface composition and state of the Monel alloy electrode were caused by the surface element enrichment of Cu, they were the main reasons for the deterioration of electrocatalytic properties of the electrode in the electrochemical reduction of nitrobenzene.The results from steady-state polarization confirm the conclusion further.
2006, 23(1): 54-58
Abstract:
Steric hindrance layer can be established when the graft polymerization of PBT prepolymer was performed onto the surface of the nano-particles, which not only increases the dispersibility of the particles, but also improves the compatibility between the nano-particles and the resin matrix.The FTIR spectrum shows that the grafted nano-particles exhibit absorption peaks which are the characteristic of the ester groups in PBT prepolymer.The Si2p peak of the grafted nano-silica in the XPS spectrum indicates that the binding energy of Si2p has shifted to the low energy side, and Si-O-C bond has been formed between SiO2 and PBT prepolymer.Vacuum plays an important role in determining the grafting amount and the length of the grafted chains.The relationship between the vacuum and chain length was investigated by TG and Mv.The lower the vacuum, the longer the grafted chains, and thus the more the mass loss.The AFM image shows that the particles dispersed in tetrachloroethane are about 50 nm in diameter, and they were almost dispersed homogeneously as original particles without any agglomeration or adhesion.The SEM image of the nanocomposite shows that the particles dispersed homogeneously in PBT matrix, there are well adhered at the interface.
Steric hindrance layer can be established when the graft polymerization of PBT prepolymer was performed onto the surface of the nano-particles, which not only increases the dispersibility of the particles, but also improves the compatibility between the nano-particles and the resin matrix.The FTIR spectrum shows that the grafted nano-particles exhibit absorption peaks which are the characteristic of the ester groups in PBT prepolymer.The Si2p peak of the grafted nano-silica in the XPS spectrum indicates that the binding energy of Si2p has shifted to the low energy side, and Si-O-C bond has been formed between SiO2 and PBT prepolymer.Vacuum plays an important role in determining the grafting amount and the length of the grafted chains.The relationship between the vacuum and chain length was investigated by TG and Mv.The lower the vacuum, the longer the grafted chains, and thus the more the mass loss.The AFM image shows that the particles dispersed in tetrachloroethane are about 50 nm in diameter, and they were almost dispersed homogeneously as original particles without any agglomeration or adhesion.The SEM image of the nanocomposite shows that the particles dispersed homogeneously in PBT matrix, there are well adhered at the interface.
2006, 23(1): 59-63
Abstract:
The photoinduced degradation of dibutyl phthalate (DBF) with TiO2 as the catalyst in aqueous solution was investigated under ultraviolet radiation.As a result, DBF could be degraded efficiently, and the efficiency was 80.1%.Acidity of the degradation system changed obviously during the degradation process.The initial pH of the solution was 6.0, but it decreased to 3.57 after 6 h degradation.Some photodegradation intermediates in the different photocatalytic steps were examined and analyzed by means of GC-MS.It is concluded that the photodegradation of DBP begins from the side chain and it can be decomposed to monobutyl phthalate, methyl benzoate and benzoic acid.After 6 h degradation, benzoic acid is one of the main products, which is difficult to decompose further under such experimental conditions.The probable degradation course is also brought forward in the paper.
The photoinduced degradation of dibutyl phthalate (DBF) with TiO2 as the catalyst in aqueous solution was investigated under ultraviolet radiation.As a result, DBF could be degraded efficiently, and the efficiency was 80.1%.Acidity of the degradation system changed obviously during the degradation process.The initial pH of the solution was 6.0, but it decreased to 3.57 after 6 h degradation.Some photodegradation intermediates in the different photocatalytic steps were examined and analyzed by means of GC-MS.It is concluded that the photodegradation of DBP begins from the side chain and it can be decomposed to monobutyl phthalate, methyl benzoate and benzoic acid.After 6 h degradation, benzoic acid is one of the main products, which is difficult to decompose further under such experimental conditions.The probable degradation course is also brought forward in the paper.
2006, 23(1): 64-68
Abstract:
Multiwalled carbon nanotubes(MWNTs) filled high-density polyethylene (HDPE) composites were prepared by melt blending.Electrical properties, especially the resistivity-temperature characteristics of the composites, were investigated.The results show that the composites filled with MWNTs have a perfect conductivity and the electrical percolation threshold is about 1%~2% (mass fraction).A special resistivity-temperature characteristic,"V-PTC" characteristic, was found, which exhibited that when the mass fraction of MWNTs exceeded the electrial percolation threshold, the resistivity of the composites first decreased (NTC effect) as the temperature increased, while it increased abruptly when the temperature approached melting point(Tm) of the matrix(PTC effect).It should be noted that this phenomenon has not been found in polymer-based composites filled with other conductive particles, such as carbon black, graphite, carbon fiber, and so on.This V-PTC characteristic is due to the expanding of the matrix volume and the relaxation of the MWNTs entanglement.Maleic anhydride grafted styrene-(ethylene-co-butylene)-sryrene copolymer(MA-g-SEBS) acts as a compatibilizer to MWNTs and HDPE, which improves the interaction between filler and polymer matrix, and thus almostly eliminated the V-PTC characteristic through restricting the movement of the filler.
Multiwalled carbon nanotubes(MWNTs) filled high-density polyethylene (HDPE) composites were prepared by melt blending.Electrical properties, especially the resistivity-temperature characteristics of the composites, were investigated.The results show that the composites filled with MWNTs have a perfect conductivity and the electrical percolation threshold is about 1%~2% (mass fraction).A special resistivity-temperature characteristic,"V-PTC" characteristic, was found, which exhibited that when the mass fraction of MWNTs exceeded the electrial percolation threshold, the resistivity of the composites first decreased (NTC effect) as the temperature increased, while it increased abruptly when the temperature approached melting point(Tm) of the matrix(PTC effect).It should be noted that this phenomenon has not been found in polymer-based composites filled with other conductive particles, such as carbon black, graphite, carbon fiber, and so on.This V-PTC characteristic is due to the expanding of the matrix volume and the relaxation of the MWNTs entanglement.Maleic anhydride grafted styrene-(ethylene-co-butylene)-sryrene copolymer(MA-g-SEBS) acts as a compatibilizer to MWNTs and HDPE, which improves the interaction between filler and polymer matrix, and thus almostly eliminated the V-PTC characteristic through restricting the movement of the filler.
2006, 23(1): 69-73
Abstract:
Organo-attapulgite clays were prepared by means of mechanical stirring and ultrasonic treatment in a hexadecyltrimethylammonium bromide (HTAB) and attapulgite clay mixture solution.The attapulgite clay and organo-attapulgite clays were characterized by using XRD, FTIR, SEM and TEM techniques.The results show that the HTAB cations were adsorbed on the surface of attapulgite needles, and dispersion of the organo-attapulgite clays showed nano-dimension.Organic contents of the two organo-attapulgite clays prepared by either mechanical stirring or ultrasonic treatment under the same conditions were 5.12% and 2.98%, respectively.The two organo-attapulgite clays were used for the preparation of organic-inorganic hybrid superabsor-bents.When the clay content was 10%, the water absorbencies of the two resulting superabsorbent composites reached 3 820 g/g and 3 323 g/g, respectively, which are higher than that of superabsorbent composite prepared with untreated attapulgite clay(2 872 g/g).
Organo-attapulgite clays were prepared by means of mechanical stirring and ultrasonic treatment in a hexadecyltrimethylammonium bromide (HTAB) and attapulgite clay mixture solution.The attapulgite clay and organo-attapulgite clays were characterized by using XRD, FTIR, SEM and TEM techniques.The results show that the HTAB cations were adsorbed on the surface of attapulgite needles, and dispersion of the organo-attapulgite clays showed nano-dimension.Organic contents of the two organo-attapulgite clays prepared by either mechanical stirring or ultrasonic treatment under the same conditions were 5.12% and 2.98%, respectively.The two organo-attapulgite clays were used for the preparation of organic-inorganic hybrid superabsor-bents.When the clay content was 10%, the water absorbencies of the two resulting superabsorbent composites reached 3 820 g/g and 3 323 g/g, respectively, which are higher than that of superabsorbent composite prepared with untreated attapulgite clay(2 872 g/g).
2006, 23(1): 74-78
Abstract:
Salicylaldehyde-5-aminosalicylic acid Schiff base was obtained from salicylaldehyde and 5-amino-salicylic acid and Nd(Ⅲ), Gd(Ⅲ), and Yb(Ⅲ) complexes with it were synthesized.Elemental analysis, molar conductance, IR,1H NMR, and TG-DTA measurements of the three rare earth complexes indicate that the Schiff base acts as a quadridentate ligand and the coordination numbers are 7 for Nd3+, and 9 for Gd3+ and Yb3+.The ligand and synthesized rare earth complexes show good bacteriostatic activities against staphyococcus aureus, escherichia cocli and withered grass bacillus.Moreover, the bacteriostatic activities of salicylaldehyde-5-aminosalicylic acid Schiff base and its Nd(Ⅲ), Gd(Ⅲ) and Yb(Ⅲ) complexes are related to the rare-earth elements themselves and increased with the increase of the concentrations of the Schiff base and its complexes.
Salicylaldehyde-5-aminosalicylic acid Schiff base was obtained from salicylaldehyde and 5-amino-salicylic acid and Nd(Ⅲ), Gd(Ⅲ), and Yb(Ⅲ) complexes with it were synthesized.Elemental analysis, molar conductance, IR,1H NMR, and TG-DTA measurements of the three rare earth complexes indicate that the Schiff base acts as a quadridentate ligand and the coordination numbers are 7 for Nd3+, and 9 for Gd3+ and Yb3+.The ligand and synthesized rare earth complexes show good bacteriostatic activities against staphyococcus aureus, escherichia cocli and withered grass bacillus.Moreover, the bacteriostatic activities of salicylaldehyde-5-aminosalicylic acid Schiff base and its Nd(Ⅲ), Gd(Ⅲ) and Yb(Ⅲ) complexes are related to the rare-earth elements themselves and increased with the increase of the concentrations of the Schiff base and its complexes.
2006, 23(1): 79-83
Abstract:
Unsaturated polyphosphoester(UPPE) containing fumarate segment in the repeat units was synthesized via condensation polymerization reaction with fumaric acid, 1,2-propylene glycol and phosphorous oxychloride as the raw materials.The structure of the polymer was characterized by FT-IR and NMR (1H,13C, 31P).In vitro drug releases of the crosslinking systems of UPPE/NVP with different contents of ciprofloxacin and different mass ratios of UPPE to NVP were studied in phosphate buffer solution(pH=7.4) at 37℃.The results indicate that a system with a less content of ciprofloxacin releases drug more rapidly when the mass ratio of UPPE to NVP is kept constantly, and a system with a higher mass ratio of NVP to UPPE releases drug more rapidly when the content of ciprofloxacin is kept constantly.
Unsaturated polyphosphoester(UPPE) containing fumarate segment in the repeat units was synthesized via condensation polymerization reaction with fumaric acid, 1,2-propylene glycol and phosphorous oxychloride as the raw materials.The structure of the polymer was characterized by FT-IR and NMR (1H,13C, 31P).In vitro drug releases of the crosslinking systems of UPPE/NVP with different contents of ciprofloxacin and different mass ratios of UPPE to NVP were studied in phosphate buffer solution(pH=7.4) at 37℃.The results indicate that a system with a less content of ciprofloxacin releases drug more rapidly when the mass ratio of UPPE to NVP is kept constantly, and a system with a higher mass ratio of NVP to UPPE releases drug more rapidly when the content of ciprofloxacin is kept constantly.
2006, 23(1): 84-88
Abstract:
The organosiloxane modified core-shell polyacrylate latex(ACR Latex) was prepared from acrylate monomer and A-174, by emulsion polymerization.The factors to affect the sandstone consolidation, including the mass fraction of ACR latex and crosslinking agent, consolidating temperature and time, and the sequence of the injection of latex and crosslinking agent, were studied.The orthogonal experiment result shows that the loss permeability of consolidation sand column can reach to the smallest if the mass fractions of latex and crosslinking agent maintain to 1.2% and 3% respectively, the consolidating temperature is kept at 65℃, consolidating time is 6 hours.
The organosiloxane modified core-shell polyacrylate latex(ACR Latex) was prepared from acrylate monomer and A-174, by emulsion polymerization.The factors to affect the sandstone consolidation, including the mass fraction of ACR latex and crosslinking agent, consolidating temperature and time, and the sequence of the injection of latex and crosslinking agent, were studied.The orthogonal experiment result shows that the loss permeability of consolidation sand column can reach to the smallest if the mass fractions of latex and crosslinking agent maintain to 1.2% and 3% respectively, the consolidating temperature is kept at 65℃, consolidating time is 6 hours.
2006, 23(1): 89-93
Abstract:
The crystallization behavior of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was investigated by means of differential scanning calorimetry(DSC).The results show that terephthalic acid(TPA) is a most effective heterogeneous nucleating agent for the crystallization of PHBV.When the mass fraction of terephthalic acid was 0.5%, the initial crystallization temperature increased from 90℃ to 110℃ and the temperature range of crystallization decreased by 2.5 times.The crystalline enthalpy increased by 20 J/g.The Avrami exponent n reached to 7.0 calculated by means of Avrami's equation, the fold surface free energy σe of PHBV decreased remarkably estimated according to Lauritzen-Hoffman theory.
The crystallization behavior of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) was investigated by means of differential scanning calorimetry(DSC).The results show that terephthalic acid(TPA) is a most effective heterogeneous nucleating agent for the crystallization of PHBV.When the mass fraction of terephthalic acid was 0.5%, the initial crystallization temperature increased from 90℃ to 110℃ and the temperature range of crystallization decreased by 2.5 times.The crystalline enthalpy increased by 20 J/g.The Avrami exponent n reached to 7.0 calculated by means of Avrami's equation, the fold surface free energy σe of PHBV decreased remarkably estimated according to Lauritzen-Hoffman theory.
2006, 23(1): 94-98
Abstract:
The new vanadium complexes VO(acac)(HB(pz)3)(1) and VO(acac) (HB(3,5-Me2pz)3)·CH3CN(2) with poly-pyrazolylborate as the ligand were synthesized.They were characterized by means of elemental analysis, IR, UV-Vis and 1H NMR techniques.In order to explore the possibility of using them as a medicine for diabetes, the toxicity of the vanadium complexes was tested by cell culture and MTT-reduction assay.Results show that the vanadium complexes can promote the growth of the cells when the concentration is lower than 10 μmol/L, but when the concentration is higher than 100 μmol/L, the survival rates decrease obviously.Toxicity is not seriously based on the active time; when it is lower than 10 μmol/L, the order of toxicity is (compound 1) >(compound 3) >(compound 2).It shows that vanadium complex (2) has a more feasibility to cure diabetes.
The new vanadium complexes VO(acac)(HB(pz)3)(1) and VO(acac) (HB(3,5-Me2pz)3)·CH3CN(2) with poly-pyrazolylborate as the ligand were synthesized.They were characterized by means of elemental analysis, IR, UV-Vis and 1H NMR techniques.In order to explore the possibility of using them as a medicine for diabetes, the toxicity of the vanadium complexes was tested by cell culture and MTT-reduction assay.Results show that the vanadium complexes can promote the growth of the cells when the concentration is lower than 10 μmol/L, but when the concentration is higher than 100 μmol/L, the survival rates decrease obviously.Toxicity is not seriously based on the active time; when it is lower than 10 μmol/L, the order of toxicity is (compound 1) >(compound 3) >(compound 2).It shows that vanadium complex (2) has a more feasibility to cure diabetes.
2006, 23(1): 99-105
Abstract:
Heteropoly complex ion with lanthanum——La(TiW11)2 was successfully intercalated into the interlayer space of Zn-Al, with Zn0.78Al0.22(OH)2·0.22C13H27COO·0.81H2O as precursor in an aqueous solution via ion exchange reaction, and a new type of pillared layered microporous compound, Zn0.76 Al0.24 (OH)·0.018[La(Ti0.97W11.5O39)2]·0.012C13H27COO·0.81H2O with higher basal space (d003=3.29 nm) was obtained.The composition, structure and properties of the new pillared material were characterized by elemental analysis, XRD, IR spectra and TG-DTA curves.The results show that myristic acid radical anion of precursor Zn0.78Al0.22(OH)2·0.22C13H27COO·0.81H2O can be almost completely replaced by complex anion[La(TiW11O39)2]13- under special controlled reaction conditions.The new pillared hydrotalcite has a good crystallinity, a regular layered structure and a good thermal stability.The orientation of the intercalated anion[La(TiW11O39)3]13- was deduced.It has also been found that the new material has a good catalytic activity and selectivity for the esterification of benzoic acid with diethylene glycol, the dehydration-cyclization of diethylene glycol, and the oxidation of benzaldehyde.
Heteropoly complex ion with lanthanum——La(TiW11)2 was successfully intercalated into the interlayer space of Zn-Al, with Zn0.78Al0.22(OH)2·0.22C13H27COO·0.81H2O as precursor in an aqueous solution via ion exchange reaction, and a new type of pillared layered microporous compound, Zn0.76 Al0.24 (OH)·0.018[La(Ti0.97W11.5O39)2]·0.012C13H27COO·0.81H2O with higher basal space (d003=3.29 nm) was obtained.The composition, structure and properties of the new pillared material were characterized by elemental analysis, XRD, IR spectra and TG-DTA curves.The results show that myristic acid radical anion of precursor Zn0.78Al0.22(OH)2·0.22C13H27COO·0.81H2O can be almost completely replaced by complex anion[La(TiW11O39)2]13- under special controlled reaction conditions.The new pillared hydrotalcite has a good crystallinity, a regular layered structure and a good thermal stability.The orientation of the intercalated anion[La(TiW11O39)3]13- was deduced.It has also been found that the new material has a good catalytic activity and selectivity for the esterification of benzoic acid with diethylene glycol, the dehydration-cyclization of diethylene glycol, and the oxidation of benzaldehyde.
2006, 23(1): 106-108
Abstract:
The chloromethylation reaction of 2-chloro-thiophene via phase transfer catalysis was carried out to synthesize 2-chloro-3-chloromethyl-thiophene, where the catalyst was tetrabutylammonium bromide (TBAB).The chloromethylation reagents used were paraformaldehyde and 37% concentrated hydrochloric acid.The structure of 2-chloro-3-chloromethyl-thiophene was confirmed by means of GC-MAS, IR and 1H NMR spectrometries.The yield was 77.6%.The O-alkylation reactions between 1-(2,4-dichloro-phenyl)-2-(1-imidazol)-ethanol and 2-chloro-3-chloromethyl-thiophene were performed in a two-phase system of organic solvent/solid NaOH under phase transfer catalytic condition.At the end, the tioconazole nitrate was formed by the addition of nitric acid.The structure of tioconazole was confirmed with IR and 1H NMR spectra.The yield of tioconazole was 53.0%.
The chloromethylation reaction of 2-chloro-thiophene via phase transfer catalysis was carried out to synthesize 2-chloro-3-chloromethyl-thiophene, where the catalyst was tetrabutylammonium bromide (TBAB).The chloromethylation reagents used were paraformaldehyde and 37% concentrated hydrochloric acid.The structure of 2-chloro-3-chloromethyl-thiophene was confirmed by means of GC-MAS, IR and 1H NMR spectrometries.The yield was 77.6%.The O-alkylation reactions between 1-(2,4-dichloro-phenyl)-2-(1-imidazol)-ethanol and 2-chloro-3-chloromethyl-thiophene were performed in a two-phase system of organic solvent/solid NaOH under phase transfer catalytic condition.At the end, the tioconazole nitrate was formed by the addition of nitric acid.The structure of tioconazole was confirmed with IR and 1H NMR spectra.The yield of tioconazole was 53.0%.
2006, 23(1): 109-112
Abstract:
A novel synthesis method of dipeptides containing glutamine is reported.Protected L-amino acids were prepared by using inexpensive phthaloyl as the protecting group.Then the phthaloyl-L-amino acids were condensed with glutamine salts by the mixed anhydride method to afford phthaloyl dipeptides.Subsequently, the phthaloyl was removed from the dipeptides with hydrazine hydrate.As a result, optically pure glutamine-containing dipeptides were obtained in good yields.
A novel synthesis method of dipeptides containing glutamine is reported.Protected L-amino acids were prepared by using inexpensive phthaloyl as the protecting group.Then the phthaloyl-L-amino acids were condensed with glutamine salts by the mixed anhydride method to afford phthaloyl dipeptides.Subsequently, the phthaloyl was removed from the dipeptides with hydrazine hydrate.As a result, optically pure glutamine-containing dipeptides were obtained in good yields.
2006, 23(1): 113-114
Abstract:
The rubber was polished by file to get its surface rough and boiled in the solution of sodium carbonate and sulphuric acid separately to remove the oil on its surface.Then, the rubber was put into the solution of chromic acid to make the surface further rougher.After that, the surface was respectively sensitized and activated by stannous chloride and palladium chloride to result in catalysis activity hubs on the surface.Finally, the rubber was put into the nickel solution, and the process of electroless nickel-plating began.The operating methods and the process of nickel-plating on the surface of rubber using dihydric hypophosphite as reductive were studied.The suitable process conditions(pH 6.9, temperature 50℃, time 2 h) were determined, the influences of several factors on the nickel-plating on the surface of rubber were also investigated.
The rubber was polished by file to get its surface rough and boiled in the solution of sodium carbonate and sulphuric acid separately to remove the oil on its surface.Then, the rubber was put into the solution of chromic acid to make the surface further rougher.After that, the surface was respectively sensitized and activated by stannous chloride and palladium chloride to result in catalysis activity hubs on the surface.Finally, the rubber was put into the nickel solution, and the process of electroless nickel-plating began.The operating methods and the process of nickel-plating on the surface of rubber using dihydric hypophosphite as reductive were studied.The suitable process conditions(pH 6.9, temperature 50℃, time 2 h) were determined, the influences of several factors on the nickel-plating on the surface of rubber were also investigated.
2006, 23(1): 115-116
Abstract:
Aminoalcohols reacted with urea at 160~180℃ for 1 h and at 200℃ for 0.5 h without solvent to give chiral 2-oxazolidinones in high yields.
Aminoalcohols reacted with urea at 160~180℃ for 1 h and at 200℃ for 0.5 h without solvent to give chiral 2-oxazolidinones in high yields.
