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1999 Volume 17 Issue 1
1999, 17(1): 1-12
Abstract:
Hybrid organic-inorganic silica materials containing organic functional groups have been preparedby the reaction of activated silica with a silane coupling reagent such as N-(2-aminoethyl)3-aminopropyltrimethoxysilane. The hybrid silica was further modified by organic compounds having abifunctional group. These modified hybrid silicas were used as catalysts for various nucleophilic reactions.And also, these were complexed with metallic ions for use as catalysts for oxygen oxidation of hydrocarbons.
Hybrid organic-inorganic silica materials containing organic functional groups have been preparedby the reaction of activated silica with a silane coupling reagent such as N-(2-aminoethyl)3-aminopropyltrimethoxysilane. The hybrid silica was further modified by organic compounds having abifunctional group. These modified hybrid silicas were used as catalysts for various nucleophilic reactions.And also, these were complexed with metallic ions for use as catalysts for oxygen oxidation of hydrocarbons.
1999, 17(1): 13-19
Abstract:
This paper provides a summarized review on the kinetics of vinyl chloride homopolymerization inthe absence and presence of chain transfer agents, of VC/DAP(diallyl phthalate) copolymerization with chainextension and/or slightly crosslinking functions, and of vinylidene chloride/VC random copolymerization.Models of rate, degree of polymerization or molecular weight, copolymer composition, gel fraction andcrosslinking density were proposed and interpreted mechanistically.
This paper provides a summarized review on the kinetics of vinyl chloride homopolymerization inthe absence and presence of chain transfer agents, of VC/DAP(diallyl phthalate) copolymerization with chainextension and/or slightly crosslinking functions, and of vinylidene chloride/VC random copolymerization.Models of rate, degree of polymerization or molecular weight, copolymer composition, gel fraction andcrosslinking density were proposed and interpreted mechanistically.
1999, 17(1): 21-26
Abstract:
Vinyl ether (VE)-based amphiphilic block copolymers with D-glucose residues as hydrophilicpendants were synthesized by CH3 CH(OiBu)Cl/ZnI2-initiated sequential living cationic copolymerization of 3-O-(vinyloxy)ethyl-1, 2:5, 6-di-O-isopropylidene-D-glucofuranose (IGVE) and isobutyl VE (IBVE ) andsubsequent deprotection. The precursor block copolymers had a narrow molecular weight distribution(Mw/Mn～1.1) and a controlled segmental composition. The solubility characteristics of the amphiphilic copolymer depended strongly on composition.Thier solvent-cast thin films were examined,under a transmission electron microscope,and could be seen to exhibit various microphase-separated surface morphologies such as spheres,cylinders,and lamellae,depending on composition.The amphiphilic copolymers with the appropriate segmental composition were found to form a stable monolayer at the air-water interface,which was successfully transferred onto a substrate by the Langmuir-Blodgett(LB) technique.The layered structure of the built-up LB films was controlled by blending the homopolymer.
Vinyl ether (VE)-based amphiphilic block copolymers with D-glucose residues as hydrophilicpendants were synthesized by CH3 CH(OiBu)Cl/ZnI2-initiated sequential living cationic copolymerization of 3-O-(vinyloxy)ethyl-1, 2:5, 6-di-O-isopropylidene-D-glucofuranose (IGVE) and isobutyl VE (IBVE ) andsubsequent deprotection. The precursor block copolymers had a narrow molecular weight distribution(Mw/Mn～1.1) and a controlled segmental composition. The solubility characteristics of the amphiphilic copolymer depended strongly on composition.Thier solvent-cast thin films were examined,under a transmission electron microscope,and could be seen to exhibit various microphase-separated surface morphologies such as spheres,cylinders,and lamellae,depending on composition.The amphiphilic copolymers with the appropriate segmental composition were found to form a stable monolayer at the air-water interface,which was successfully transferred onto a substrate by the Langmuir-Blodgett(LB) technique.The layered structure of the built-up LB films was controlled by blending the homopolymer.
1999, 17(1): 27-35
Abstract:
Careful measurements of the dilute solution viscosities of polyethylene glycol and polyvinylalcohol in water were carried out. The reduced viscosities of both polymer solutions plot upward curves atextremely dilute concentration levels similar to the phenomena observed for many polymer solutions in theearly 1950's. Upon observation of the changes of the flow times of pure water in and the wall surfacewettability of the viscometer after measuring solution viscosity, a view was formed that the observed viscosity abnormality at extremely dilute concentration regions is solely due to the effect of adsorption of polymer chains onto the wall surface of viscometer.A theory of adsorption effect based on the Langmuir isotherms was proposed and a mathematical analysis for data treatment was performed.The theory could adequately describe the existing viscosity data.It seems necessary to correct the viscosity result of dilute polymer solutions measured by glass capillary viscometer by taking into account the effect of adsorption in all cases.
Careful measurements of the dilute solution viscosities of polyethylene glycol and polyvinylalcohol in water were carried out. The reduced viscosities of both polymer solutions plot upward curves atextremely dilute concentration levels similar to the phenomena observed for many polymer solutions in theearly 1950's. Upon observation of the changes of the flow times of pure water in and the wall surfacewettability of the viscometer after measuring solution viscosity, a view was formed that the observed viscosity abnormality at extremely dilute concentration regions is solely due to the effect of adsorption of polymer chains onto the wall surface of viscometer.A theory of adsorption effect based on the Langmuir isotherms was proposed and a mathematical analysis for data treatment was performed.The theory could adequately describe the existing viscosity data.It seems necessary to correct the viscosity result of dilute polymer solutions measured by glass capillary viscometer by taking into account the effect of adsorption in all cases.
1999, 17(1): 37-41
Abstract:
Blends of PC and PPSQ (A) with high Mw and good ladderlike regularity or PPSQ(B) withlow M_w and more defective Si-atoms in its structure have been prepared by solution casting. Thedispersed spheres (PPSQ(A)-rich) are unevenly dispersed in the continuous PC-rich phase and there isno phase-inversion as PPSQ(A) content increases when the percentage of PPSQ(A) is not more than70%. PPSQ(B)-rich spheres are evenly dispersed in the continuous phase (PC-rich) and phase-inversion occurs when PPSQ(B) percentage is up to 70%.Tg of PPSQ(A)/PC or PPSQ(B)/PC at some compositions are lower than that of pure PC due to the enlarged free-volume of PC-rich phase because some spheres of rigid PPSQ chains are included in the PC-rich phase.PC and PPSQ(A) or PPSQ(B) are partially compatible.The compatibility of PC and PPSQ(B) is better than that of PC and PPSQ (A) with high Mw and good ladderlike regularity.Heat history has some influence on the TgS and compatibility of PPSQ(A)/PC and PPSQ/PC blends.
Blends of PC and PPSQ (A) with high Mw and good ladderlike regularity or PPSQ(B) withlow M_w and more defective Si-atoms in its structure have been prepared by solution casting. Thedispersed spheres (PPSQ(A)-rich) are unevenly dispersed in the continuous PC-rich phase and there isno phase-inversion as PPSQ(A) content increases when the percentage of PPSQ(A) is not more than70%. PPSQ(B)-rich spheres are evenly dispersed in the continuous phase (PC-rich) and phase-inversion occurs when PPSQ(B) percentage is up to 70%.Tg of PPSQ(A)/PC or PPSQ(B)/PC at some compositions are lower than that of pure PC due to the enlarged free-volume of PC-rich phase because some spheres of rigid PPSQ chains are included in the PC-rich phase.PC and PPSQ(A) or PPSQ(B) are partially compatible.The compatibility of PC and PPSQ(B) is better than that of PC and PPSQ (A) with high Mw and good ladderlike regularity.Heat history has some influence on the TgS and compatibility of PPSQ(A)/PC and PPSQ/PC blends.
1999, 17(1): 43-48
Abstract:
By using diphenyliodonium salts with different counterions as photo acid generators (PAGs), theeffect of acidity on ring-opening polymerization of epoxy monomers and polycondensation of polyol withhexamethoxymethyl melamine (HMMM) was studied. The result shows that the rate of ring-openingpolymerization is evidently dependent on the acidity of the acid and strong photo-generated acid is required.However, there is a leveling effect in the polycondensation system; if the photo-generated acid is stronger than protonated HMMM,the acidity does not obviously affect the polycondendation rate.
By using diphenyliodonium salts with different counterions as photo acid generators (PAGs), theeffect of acidity on ring-opening polymerization of epoxy monomers and polycondensation of polyol withhexamethoxymethyl melamine (HMMM) was studied. The result shows that the rate of ring-openingpolymerization is evidently dependent on the acidity of the acid and strong photo-generated acid is required.However, there is a leveling effect in the polycondensation system; if the photo-generated acid is stronger than protonated HMMM,the acidity does not obviously affect the polycondendation rate.
1999, 17(1): 49-55
Abstract:
Heterojunctions between polyaniline (PANI) and n-type porous silicon (PS), Al/PS-PANI/Au cell,were fabricated, and the rectifying parameters of this heterojunction diode were measured as a function of thepreparation conditions of PANI and PS, the electronic structure of PANI as well as cell structure. Therectifying parameters of Al/PS-PANI/Au cell were determined to be γ= 1 .8×101～ 1 .0×105 for the rectifyingratio at 3V, n = 3 ～12 for the ideal factor,j0 = 8.0×10-5～5.6×10-2 mA/cm2 for the reversed saturated current density,and φb=0.67～0.83 V for the barrier height,respectively.The best rectifying heterojunction diode made between PANI and n-type PS with higher rectifying factor (γ=1.0×105 at 3V ),output current(>1500mA/cm2 at 3V ) and lower ideal factor(n=3.3)was obtained by preventing the oxidation of PS before evaporating Al electrode.
Heterojunctions between polyaniline (PANI) and n-type porous silicon (PS), Al/PS-PANI/Au cell,were fabricated, and the rectifying parameters of this heterojunction diode were measured as a function of thepreparation conditions of PANI and PS, the electronic structure of PANI as well as cell structure. Therectifying parameters of Al/PS-PANI/Au cell were determined to be γ= 1 .8×101～ 1 .0×105 for the rectifyingratio at 3V, n = 3 ～12 for the ideal factor,j0 = 8.0×10-5～5.6×10-2 mA/cm2 for the reversed saturated current density,and φb=0.67～0.83 V for the barrier height,respectively.The best rectifying heterojunction diode made between PANI and n-type PS with higher rectifying factor (γ=1.0×105 at 3V ),output current(>1500mA/cm2 at 3V ) and lower ideal factor(n=3.3)was obtained by preventing the oxidation of PS before evaporating Al electrode.
1999, 17(1): 57-63
Abstract:
The synthesis and characterization of a series of novel comb-like polymethacrylates bearingheterocyclic azo group and mesogenic group are described. The thermal properties of the polymers such asthermal stability and phase transition behavior were investigated by thermogravimetric analysis, differentialthermal analysis and polarizing optical microscopy techniques. The experimental results show that all thesynthesized polymers do not exhibit liquid crystallinity except the homopolymer of the mesogenic monomer MAPB2 nad the glass transtion temperatures of the polymers increase with increasing content of azo moiety in polymers linearly.
The synthesis and characterization of a series of novel comb-like polymethacrylates bearingheterocyclic azo group and mesogenic group are described. The thermal properties of the polymers such asthermal stability and phase transition behavior were investigated by thermogravimetric analysis, differentialthermal analysis and polarizing optical microscopy techniques. The experimental results show that all thesynthesized polymers do not exhibit liquid crystallinity except the homopolymer of the mesogenic monomer MAPB2 nad the glass transtion temperatures of the polymers increase with increasing content of azo moiety in polymers linearly.
1999, 17(1): 65-70
Abstract:
Five chitosan derivatives, i.e. O-butyryl chitosan, O-benzoyl chitosan, N-phthaloyl chitosan, N-maleoyl chitosan and O-cyanoethyl chitosan, were prepared from chitosan. All of them had better solubilitythan chitosan, and demonstrated lyotropic liquid crystalline behavior in various solvents. The critical liquidcrystalline behavior of three O-substituted chitosan derivatives was evidently different from two N-substituted analogues. Typical fingerprint textures of cholesteric phase were only observed in three O-substitued derivatives.The critical concentration(v/v%) of three O-substitued derivatives does not depend on the acidity of acidic solvents.
Five chitosan derivatives, i.e. O-butyryl chitosan, O-benzoyl chitosan, N-phthaloyl chitosan, N-maleoyl chitosan and O-cyanoethyl chitosan, were prepared from chitosan. All of them had better solubilitythan chitosan, and demonstrated lyotropic liquid crystalline behavior in various solvents. The critical liquidcrystalline behavior of three O-substituted chitosan derivatives was evidently different from two N-substituted analogues. Typical fingerprint textures of cholesteric phase were only observed in three O-substitued derivatives.The critical concentration(v/v%) of three O-substitued derivatives does not depend on the acidity of acidic solvents.
1999, 17(1): 71-74
Abstract:
Ladder-like polydecylsilsesquioxane (LPDS) was synthesized by a preamminolysis reaction ofdecyltrichlorosilane with ethylene diamine, followed by hydrolysis and polycondensation reaction. LPDS issoluble in a nonpolar solvent such as heptane and insoluble in a high polar solvent such as methanol. It wascharaterized by IR, 1H-NMR, 29Si-NMR, GPC and X-ray diffraction.
Ladder-like polydecylsilsesquioxane (LPDS) was synthesized by a preamminolysis reaction ofdecyltrichlorosilane with ethylene diamine, followed by hydrolysis and polycondensation reaction. LPDS issoluble in a nonpolar solvent such as heptane and insoluble in a high polar solvent such as methanol. It wascharaterized by IR, 1H-NMR, 29Si-NMR, GPC and X-ray diffraction.
1999, 17(1): 75-79
Abstract:
Polymer LB films containing photofuntional groups were prepared by the copolymerization of N-dodecylacrylamide (DDA), which has an excellent property to form a stable monolayer and LB multilayerswith photofunctional monomers. Tris(2, 2'-bipyridine) ruthenium complex, Ru(bpy)32+, one of the most well-known redox-active sensitizer, was incorporated into the DDA copolymer. The photogalvanic effect based onthe photoinduced electron transfer using the ruthenium complex in the polymer LB monolayer was discussed.
Polymer LB films containing photofuntional groups were prepared by the copolymerization of N-dodecylacrylamide (DDA), which has an excellent property to form a stable monolayer and LB multilayerswith photofunctional monomers. Tris(2, 2'-bipyridine) ruthenium complex, Ru(bpy)32+, one of the most well-known redox-active sensitizer, was incorporated into the DDA copolymer. The photogalvanic effect based onthe photoinduced electron transfer using the ruthenium complex in the polymer LB monolayer was discussed.
1999, 17(1): 81-86
Abstract:
3 -Ethynyl-4-(trimethylsilyl)thiophene (1a) and 3 -ethynyl-4-bromothiophene (1 b ) selectivelyundergo acetylene polymerizations in the presence of the MoCl5- and WCl6-Ph3SiH catalysts to give soluble,high-molecular-weight poly(thienylacetylenes) (2) (Mw up to 602000) in high yields (up to 100%). Lighttransmission spectra of THF solutions of 2 continuously red-shift with increasing concentration. Theconcentratochromism shows a logarithmic concentration dependence; that is, the optical transitions of 2 are predictably tunable by simply changing their concentrations.
3 -Ethynyl-4-(trimethylsilyl)thiophene (1a) and 3 -ethynyl-4-bromothiophene (1 b ) selectivelyundergo acetylene polymerizations in the presence of the MoCl5- and WCl6-Ph3SiH catalysts to give soluble,high-molecular-weight poly(thienylacetylenes) (2) (Mw up to 602000) in high yields (up to 100%). Lighttransmission spectra of THF solutions of 2 continuously red-shift with increasing concentration. Theconcentratochromism shows a logarithmic concentration dependence; that is, the optical transitions of 2 are predictably tunable by simply changing their concentrations.
1999, 17(1): 87-90
Abstract:
Optically active (R)-(+)-2, 2' -bis(2 -trifluoro-4 -aminophenoxy)- 1, 1' -binaphthyl was prepared from1, 1'-bi-2-naphthol. The optically active aromatic polyimide was also successfully synthesized. This newpolymer has good solubility, thermal stability etc. Its specific rotation was found to be +174°, and itschiroptical property was also studied.
Optically active (R)-(+)-2, 2' -bis(2 -trifluoro-4 -aminophenoxy)- 1, 1' -binaphthyl was prepared from1, 1'-bi-2-naphthol. The optically active aromatic polyimide was also successfully synthesized. This newpolymer has good solubility, thermal stability etc. Its specific rotation was found to be +174°, and itschiroptical property was also studied.
