THE SYNTHESIS AND STUDIES ON PALLADIUM CATALYSTS ANCHORED ON CHELATE RESIN

A chelate resin with 8-aminoquinoline group attached to a styrene-divinybenzene copolymer matrix was reacted with PdCl_2, forminga polymeric palladium complex, which was reduced with different reducing agents, such as hydrogen, stannous chloride, sodium borohydride, lithium aluminum hydride, hydrazine and basic aqueous methanolic solution and thus the polymer-supported palladium (Ⅱ) complex, colloidal palladium and palladium complex with different valence states were obtained. The hydrogenation of n-hexene in methanol at 40℃ under atmospheric hydrogen pressure and the selective hydrogenation of 1,5,9-cyclododecatriene at 100℃ under 20 kg/cm~2 hydrogen pressure were studied. The results showed that the palladium complexes With different valence states prepared with hydrazine or methanol-water (pH=11) were effective catalysts for the hydrogenation of olefins. The loss of palladium on catalysts was correlated to the palladium dispersion and valence states. It was found thst the loss of palladium decreas     

THE THEORY OP BOUNDARIES IN ISOBARIC ISOPLETHS(Ⅰ)——REGULAR SECTIONS

According to the theory of the relation between neighboring phase regions {abbreviated to NPRs) and their boundaries in isobaric phase diagrams,we discuss systematically the relation between the characteristics of boundaries and the combinations of the phases of NPRs in isobaric isopleths.There are only three types and seven subgroups of boundaries of different character and the concrete characteristics of them have been determined.     

STUDIES ON NATURAL AND MODIFIED PEPTIDE Trichosanthes TRYPSIN INHIBITORS

A peptide trypsin inhibitor was isolated and purified from the roots of Trichosanthes kirilowii (a Chinese medical herb) by using immobilized anhydro-trypsin affinity chromatography and HPLC C_(18) column reverse chromatography. It contains two major components, both consisting of 27 amino acid residues with three pairs of disulfide bonds. The sequence determination indicated that the difference between them is only in the ninth position, being Gln and Lys, respectively. The peptide bond of the inhibitor reactive site Arg-Ile (3--4) is easy to cleave at low pH by trypsin, resulting in a modified inhibitor. It might be the smallest naturally occurring protein inhibitor so far known. The modification reaction of the Trichosanthes inhibitor with trypsin is similar to the catalytic enzyme-substrate reaction. The dissociation constant of the modified inhibitor with trypsin is around fourfold that of the natural inhibitor.     

STUDIES ON THE OXIDATION AND GRAFT COPOLYMERIZATION OF POLY(ETHER-URETHANE)

A new method of graft copolymerization of acrylamide (AAM) on poly(ether-urethane) (PEU) which was prepared from poly(tetramethylene ether) glycol (PTMG), 4,4'-diphenylmethane diisocyanate (MDI) and ethylene diamine or butanediol extender was investigated. Hydroperoxide group was first introduced onto the surface of PEU through photo-oxidation in the presence of hydrogen peroxide, then it was reacted with ferrous ion or N,N-dimethyl toluidine (DMT) to initiate AAM graft copolymerization on PEU surface. The graft reaction could be carried out effectively at low temperature. The formation of graft copolymer has been verified by its water absorption % and the scanning electron microscopy photographs. Some model compounds of PEU soft segment and hard segment were synthesized in order to clarify the site of graft reaction. The results of oxida-tion and graft copolymerization of model compounds showed that this graft copolymerization possesses higher selectivity, and it takes place predominately at the polyether segments, because the ether linkage in soft segment is very sensitive to oxidation and can form hydroperoxide easily. Thus, the grafting site appears to be at α-carbon of the ether linkage.     

THEORETICAL STUDIES ON THE STRUCTURES AND REACTIVITY OF SILYLENOIDS (Ⅰ)——STRUCTURES AND ISOMERIZATION OF SILYLENOID H_2SiLiCl

The structures of silylenoid H_2SiLiCl have been studied by RHF/3-21G gradient method. Three equilibrium states and two isomerization transition states are located. The electronic energy, Mulliken populations, dipole moments and frontier molecular orbitals (FMO) of every structure and the isomeric barriers are also given and analyzed. Further single point calculations on the 3-21G optimum geometries were performed using 6-21G basis set. The calculations show that three-membered ring structure of H_2SiLiCl is the most stable and detectable, and the "classical" tetrahedral form is not the local minimum on the potential energy surface.     

STUDIES ON HIGH SOLID CONTENT AND STABLEEMULSIFIER-FREE EMULSION POLYMERIZATION

1.INTRODUCTIONEmulsifier-freeemulsionpolymerizationhasrecentlyreceivedmoreandmoreattentionduetoitsacademicandpracticalinterest.Latexesofmono-disperseandcleanthatwithoUtremovablesurfactantcanbeobtained.Inaddition,materialsofhigheradhesionandwaterresistancecanbeprepared.Especially,itcanavoidfromenvironmentalpollution.UPtodate,emulsifier-freeemulsionpolymeriZationismainlypreparedbyintroducingionicinitiators,*.Towhomcorrespondenceshouldbeaddressedamphiphilicoligomers,hydrophilic,nonionicori…     

STUDIES ON THE OXIDATION AND GRAFT COPOLYMERIZATION OF POLYETHERS

Polyethers could form hydroperoxide under air-oxidation or photo-oxidation in the presence of H_2O_2. The scission of ether linkage induced by moderate oxidation was prevented by controlling the reaction time and hydroperoxide concentration. The oxidation rate was affected by the end groups of polyethers. The decreasing order of oxidation rate for various poly(tetramethylene ether) glycol derivatives having different end groups are as follows: poly(tetramethylene ether) glycol (PTMG)>poly(tetramethylene ether)acetate (PTMGAC) >poly(tetramethylene ether) phenyl carbamate (PTMGPC). The urethane end groups in PTMGPC increase the resistance toward oxidation. Polyether hydroperoxide reacts with ferrous ion or N,N-dimethyl toluidine (DMT) to form polymericoxy radical which then initiates the graft copolymerization of vinyl monomers at low temperature, and was devoid of homopolymerization. The copolymer after separation and purification was proved to be a graft one by IR analysis and elemental analysis.     

STUDIES ON FLUORESCENCE ENHANCING EFFECT AND ALKALINE DEGRADATION MECHANISM OF DOXYCYCLINE AND METHACYCLINE

Degradation reaction of doxycycline or methacycline was carried outin KOH solution and intense fluorescence was obtained.A degradationmechanism of doxycycline or methacycline was suggested.     

in-situ ESR AND RAMAN SPECTROSCOPIC STUDIES ON ELECTROPOLYMERIZATION OF PYRROLE

The in-situ transient ESR measurements reveal that the oxidized structure (PP++) of polypyrrole (PP) films has an electrocatalytic activity to the oxidation of pyrrole during the electropolymerization process. Surface-enhanced resonance Raman scattering (SERRS) effect was used to probe the structure of PP films in very early stages of the polymerization on gold electrodes. It is of special interest that the electropolymerization can take place at much less positive potentials (about 300 mV) under the irradiation of light. This photocatalytic effect may be applied to the pattern deposition of polymers.     

STUDIES ON MISCIBILITY AND MORPHOLOGICAL FEATURES OF BLENDS OF LC COPOLYESTER AND PET

The morphology of a special blend system composed of liquid crystalline aromatic random copolyester (LCP) and semiflexible polyester PET over the whole composition range has been studied by means of polarized microscope, density measurement, DSC, FTIR and SEM. Based on the microscopic observation, it is found that under suitable mechanical mixing condition, LCP may be rather homogeneously dispersed in the PET matrix, with the middle composition range of the contents of LCP at 30--70 wt % the anisotropic and isotropic phase segregation appears, while with LCP contents over 80 wt% the blends exhibit wholly anisotropie. The DSC thermographs of the melt-pressed and quenched films show single T_(?), T_(cc) and T_m. T_(?) increases with increasing content of LCP and ap, proaches to the T_(?) of pure LCP. The experimental results indicate that the two components of this blend system are miscible, there exist some specific interactions between them.     

ELECTROCHEMICAL STUDIES ON CONDUCTING COMPOSITE FILMS FROM POLYURETHANE AND POLYPYRROLE

A study on the electrooxidative polymerization of pyrrole onto polyurethane-coated platinum electrodes and the electrochemical properties of the composite polyurethane/polypyrrole films (PU/PPy) as-prepared is presented. It is found that polypyrrole grows layer by layer from the polyurethane/platinum interface through the polyurethane matrix, and ca. 20 wt.% of polypyrrole will fill up the matrix. Cyclic voltemmograms show that the composite films are porous, and the reduction-reoxidation (redox) rate of the composite films is limited by the diffusion of counteranions through the films. Larger anion size leads to slower diffusion process. The composite films can also act as modified electrodes.     

STUDIES ON O-ALKYL O-ARYLPHOSPHORO- (THIOUREIDO)-THIOATES AND O-ALKYL PHOSPHORO-BIS-(THIOUREIDO)THIOATES

Two series of new organic phosphorus compounds with the general formula Ⅰ and Ⅱ have been prepared by the reaction of thc phosphoro-(isothioeyanatido) thioates and phosphoro-bis-(isothiocyanatido) thioates separately with amines.where R=Et; Ar=2-NO_2-4-Meph, 2, 4-Cl_2ph; NR~1R~2=NMeMe, NHC_3H_7-iso, NEtEt, Result from the preliminary bioassay showed that some of these compounds have fairly good herbieidal activities, especisllyThe structure of these compounds has been confirmed by IR and NMR.     

STUDIES ON ION IMPLANTATION AND ELECTRICAL PROPERTIES OF POLYACETYLENE FILMS

The effects of ion implantation on ployacetylene films PA have been studied with Ar~+, Fe~+, C1~+, I~+, Na~+ and K~+ ions in the energy range of 15—30 keV. The changes of PA films in the electrical conductivity, due to chemical doping and ion implantation in relation to their structure and depth profiles of impurities, were measured through infrared (ATR/FTIK), Rutherford backscattering spectrometry (RBS) and the four probe technique. In all cases, ion implantation of active ions exhibits the same effects as chemical doping. The formation of p-n junction is observed at the interface of implanted region and chemical doped PA substrate. The mechanism of interaction process between ion beam and polymer is also discussed.     

STUDIES OF SURFACE PHOTOVOLTAGE PROPERTIES AND CHARGE TRANSFER ON TRANSITION METAL PORPHYRIN COMPLEX （Ⅰ）

ＳＴＵＤＩＥＳ ＯＦ ＳＵＲＦＡＣＥ ＰＨＯＴＯＶＯＬＴＡＧＥ ＰＲＯＰＥＲＴＩＥＳ ＡＮＤ ＣＨＡＲＧＥ ＴＲＡＮＳＦＥＲ ＯＮ ＴＲＡＮＳＩＴＩＯＮ ＭＥＴＡＬ ＰＯＲＰＨＹＲＩＮ ＣＯＭＰＬＥＸ （Ⅰ） ￥ＪｉｅＺＨＡＮＧ；ＤｅＪｕｎＷＡＮＧ；...     

STUDIES ON THE RELATIONSHIP BETWEEN THE HELICAL STRUCTURE AND OPTICAL ACTIVITIES OF SOME CHIRAL CYCLICESTERS Ⅰ

ＳＴＵＤＩＥＳＯＮＴＨＥＲＥＬＡＴＩＯＮＳＨＩＰＢＥＴＷＥＥＮＴＨＥＨＥＬＩＣＡＬＳＴＲＵＣＴＵＲＥＡＮＤＯＰＴＩＣＡＬＡＣＴＩＶＩＴＩＥＳＯＦＳＯＭＥＣＨＩＲＡＬＣＹＣＬＩＣＥＳＴＥＲＳⅠ￥ＢｉｎｇＤＥＮＧ（ＤｅｐａｒｔｍｅｎｔｏｆＣｈｅｍｉｓｔｒ...     

MOLECULAR BEAM STUDIES ON ADSORPTION-DESORPTION KINETICS OF CO AND H_2 ON Ni SURFACE

Adsorption-desorption kinetics of CO and H_2 on Ni surface were studied with molecular beam relaxation spectrometry. It is found that there are two adsorbed states in the substrate temperature range 330K相似文献   

STUDIES ON ULTRASONIC ABSORPTION AND VISCO-RELAXATION OF POLY (ETHYLENE GLYCOL) AQUEOUS SOLUTIONS

Ultrasonic absorption and velocity measurements were made on aqueous solutions of poly (ethylene glycol)(PEG)of different molecular weights and concentrations, using a pulse sender-receiver ultrasonic generator, Measurements were obtained at a frequency of 2MHz. , and a temperature of 293 K. The results show a linear increase of the Values of velocity, density and viscosity with increase of molecu lar weight and concentration of PEG. On the contrary, the attenuation values decreased with increase of molecular weight and concentration of PEG. A mathematical equation correlating relaxation amplitude and molecular weight of the polymer is suggested. This was applied to calculate the molecular weights of unknown samples of PEG from their measured relaxation amplitude. The results obtained were in good agreement with those obtained from osmometry.     

ESCA STUDIES OF FORMIC AND ACETIC ACIDS ADSORPTION AND DECOMPOSITION ON PREOXIDISED IRON SURFACE

XPS has been applied to study the interactions of formic and acetic acids with preoxidised iron surfaces. Exposure of the surface to acetic acid at 300 K would result in two Cls peaks of similar intensities at 285.2 eV and 289.0 eV B.E. (Binding Energy). An Ols component with FWHM about 2.2 eV was also observed at 532.0 eV B.E. It was suggested that CH_3COOH adsorbed as CH_3COO(a) and OH(a) on the surface according to surface acid-base interaction: CH_3COOH(g)+O~(2-)(a)(?) CH_3COO(a)+OH(a) (1) The above mechanism was strongly supported stoichiometrically, using the Roberts—Carley equation for surface concentration calculations. When a preoxidised iron surface was exposed to formic acid at 300 K, two Cls peaks at 285.6 eV and 289.1 eV B.E. were clearly observed. The Cls peak at 289.1 eV B.E. was attributed to HCOO(a). Its formation mechanism also belongs to the kind of surface acid-base interaction: HCOOH(g)+O~(2-)(a)(?)HCOO(a)+OH(a) (2) The other Cls peak at 285.6 eV was proposed to be CH_xO(a). It was     

COMPATIBILITY STUDIES ON POLYMER/WAX AND POLYMER/RESIN-ASPHALTENE BY VISCOMETRY AND PHOTOMICROGRAPHY

The compatibility of mixtures of polymeric pour point depressants, i.e. poly(ethylene-co-vinylacetate) (EVA), poly (EVA-graft-octadecylacrylate) (EVA-g-POA ), poly (ethylene-co-octadecylacrylate) (EOA) and poly(ethylene oxide-co-propylene oxide) (EO-co-PO) withwax or resin-asphaltene from crude oil have been studied by means of dilute-solution vis-cometry. It was found that each mixture pair is incompatible, but the degrees of incompati-bility are quite different, which are in good agreement with the results from photomicrog-raphy.