MEASUREMENT OF UNPERTUBED DIMENSION 0F POLYMER

The unperturbed dimension of polymer is measured by a gel permeation chromatography (GPC)coupling with viscometer. The intrinsic viscosities of the fractions are measured with an automaticviscometer, and the molecular weight of the fractions are calculated based on the universal calibration.Using a theoretical expression with linearized Mark-Houwink's equation an unperturbed dimensionis obtained by extrapolating to the unperturbed state. The results agree with the values measuredby conventional method comparisons with various theoretical expressions are made.     

SYNTHESIS AND CRYSTAL STRUCTURE OF CARBOXYETHYL-TRICHL0ROGERM ANIUM

<正> C3H5Cl3GeO2, Mr = 252. 01, monoclinic, space group P21/n with a=6. 828(1),b= 10. 069(2) ,e= 12. 196(2) A ,B=101. 94(1) ,Z= 4,V= 820. 3A3, Dc=2. 041gcm-3, (MoKa) = 0.71073A,u=48. 96cm-1,F(000) = 647. 88. The Ge atom is coordinated by three chloro atoms and one carbon atom from carboxyethyl, forming an irregular tetrahedral geometry with average Ge-Cl distance of 2. 130(2) and the Ge-C distance of 1.946(5)A. Each two molecules are bound together by hydrogen bonds between the carboxyl groups to form a dimer.     

SYNTHESIS AND CHARACTERIZATION OF A SILICA-SUPPORTED CARBOXYMETHYLCELLULOSE PLATINUM COMPLEX AND ITS CATALYTIC BEHAVIORS FOR HYDROGENATI0N OF AR0MATICS

A silica-supported carboxymethylcellulose platinum complex (abbreviated as SiO_2-CMC-Pt) has been prepared and characterized by XPS. Its catalytic properties for hydro-genation of aromatic compounds were studied. The results showed that this catalystcould catalyze the hydrogenation of phenol, anisol, p-cresol, benzene and toluene to cyclo-hexanol, cyclohexyl methyl ether, p-methyl cyclohexanol, cyclohexane and methylcyclo-hexane, respectively in 100% yield at 30℃ and 1 atm. In the hydrogenation of phenol,COO/Pt ratio in SiO_2-CMC-Pt has much influence on the initial hydrogenation rate andthe selectivity for the intermediate product, cyclohexanone. The highest initial rate andthe highest yield of cyclohexanone both occur at COO/Pt ratio of 6. The complex is stableduring the reaction and can be used repeatedly.     

THE OBSERVATION OF INTERNAL MOTION OF LINEAR POLYSTYRENE CHAINS IN CYCLOHEXANE AROUND 0 TEMPERATURE

A high molecular weight (M_w=1.85×10~7) polystyrene (PS) with narrow distribution was prepared by high vacuum anionic polymerization in tetrahydrofuran.By use of dynamic light scattering,the dynamics of PS chains in cyclohexane was studied around theθtemperature.For the first time,we have observed the internal motion of polymer chains in solutions below theθtemperature by using dynamic light scattering at smaller angles (even qR_g<1).     

CHINESE JOURNAL OF CHEMISTRY Vol.2 0 No .1 1 November 2 0 0 2 AUTHOR INDEX

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SYNTHESES AND CHARACTERIZATI0N OF Si-CONTAINING POLYESTER-POLYETHER MULTIBLOCK COPOLYMERS

A series of Si-containing polyester-polyether multiblock copolymers were synthesizedby transesterification and melt copolycondensation of organosilicon monomers [1, 1, 3, 3-tetramethyl-1, 3-bis (p-carbomethoxyphenyl) disiloxane] (I ) or dimethyl bis (p-carbometh-oxyphenyl) silane] (II) and dimethyl terephthalate (DMT), with 1, 4-butanediol, poly-tetramethylene glycol (PTMG) respectively. The organosilicon monomers were preparedby Grinard reaction, oxidation and esterification. The structures of the above monomers(I), (II) and the copolymers were characterized by MS anal. and ~1H-NMR.     

AMINATION OF ETHANOL WITH AMM0NIA OVER H βZEOLITE

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PHOTOPOLYMERIZATION OF MMA INITIATED BY CYANINE DYE AND HEXAARYLBIIMIDAZ0LE

The photoinitiating system composed of 1-ethyl-3'-methylthiacyanine bro-mide (C-I), 2-chlorohexaarylbiimidazole (o-Cl-HABI) and 3-mercapto-4-methyl-4H-1, 2, 4-triazole (MTA), which act as sensitizer, initiator and hydrogen-donor respectively, can beused to initiate the polymerization of methyl methacrylate (MMA). The kinetic study wascarried out in trichloromathane solution at 30℃ by using dilatometry. The relation be-tween the polymerization rate and the concentrations of C-I, o-Cl-HABI, MTA and MMAwas studied.     

STUDY ON MAGNETIC FIELD-INDUCED 0RIENTATI0N OF A CHIRAL SIDE-CHAIN LIQUID CRYSTAL POLYACRYLATE USING INFRARED DICHROISM

Magnetic field-induced orientation of a chiral side chain liquid crystalline polyacrylate(P-11) was studied by using IR dichroism. For the investigated P-11, it has been shown thatthe magnetic alignment takes place over the entire temperature range between its meltingpoint and clearing point and the orientation level is strongly temperature-dependent, thedevelopment with time of the magnetic orieatation follows an exponeotial-type relation,and the smectic phase state influences the thermal relaxation process in the absence of themagnetic field.     

REACTIONS OF 1-ACETOXY ALLYLIC PHOSPHONATES UNDER PALLADIUM(0) CATALYSIS

l-Acetoxy allylic phosphonates rearrange regioselectively to γ-acetoxy α,β-unsaturated phosphonates under the catalysis of Pd(0). l-Acetoxy allylic phosphonates act as the precursors of phosphonatedπ-allylic cations in palladium(0) catalyzed reactions[1]. The reactions of l-acetoxy allylic phosphonates under palladium(0) catalysis with nucleophiles have been reported. 1-4 These reactions are highly regio- and stereoselective. We wish to report here the palladium(0) catalyzed reaction of l-acetoxy allylic phosphonates in the absence of a nucleophile.     

STUDY ON STYRENE-BUTADIENE BLOCK COPOLYMER FOR THE MODIFICATI0N OF TIRE TREAD

This paper mainly deals with the design and synthesis of a novel styrene-butadieneblock copolymer. When this copolymer is used in the tread portion of tyres, it can improvewet skid resistance and reduce rolling resistance without sacrificing its general physical-mechanical properties. The visco-elastic curve of tire tread using the novel copolymer asits rubber portion was showed. Reactivity ratios for two monomers in the polymerizingsystem were calculated. The diagrams of differelitial, integral and finite difference calculithroughout the whole molecular chain were presented. The influence of the micro- andmacro-structure of the copolymer chain on wet skid resistance and rolling resistance wasdiscussed     

RHEOLOGICAL PROPERTIES OF LIQUID CRYSTALLINE COPOLY (ρ-HYDR0XYBENZ0ATE/BISPHENOL A TEREPHTHALATE)

Various aspects of the rheological behaviour of liquid crystalline copolyesters, i.e.,samples of copoly (p-hydroxybenzoate / bisphenol A terephthalate), were explored by usingInstron capillary rheometer. The experimental results indicated that the apparent viscositywas affected significantly by shear rate, melt temperature and p-hydroxybenzoate unit con-tent. The flow activation energies △E_η are in the range of 205.1 to 74.5 kJ/mol, dependingon the shear rate of 10-1000 s~(-1), at temperature 568-603K. These copolyesters exhibit ayield phenomenon in the shear flow, and the values of yield stress decrease with increasingtemperature. It is quite unusual that the extrudate of the copolyester shows the smallerswelling ratio even than unity at the lower temperature and lower shear rates.     

THE GROWTH OF SINGLE CRYSTALS OF (L-ARGININE)~(B_0) BOVINE INSULIN AND THEIR PRELIMINARY X-RAY CRYSTALLOGRAPHIC ANALYSIS

The crystals of (L-Arg)~(B_0) bovine insulin large enough for X-ray structure analysis havebeen grown by vapour diffusion in a buffer containing citrate, acetone and zinc chloride.The X-ray diffraction of the crystals extends to 3.0 A spacing. The crystals belong tothe trigonal system with unit cell dimension of a=b=81.82A, c=35.05A, α=β=90°, γ=120°,space group R3. There are two insulin molecules in the crystallographic asymmetric unit.     

THEORETICAL ANALYSIS OF KINETICS OF NONISOTHERMAL CRYSTALLIZATION OF POLYMERS

The classical crystallization theories proposed by Avrami, Evans, and Mandelkern wereextended to the nonisothermal situation. The expressions derived from the classical equations canbe expressed in either the differential form or the integral form. A method was provided so as toobtain the parameters characterizing the crystallization rate and mechanism from DSC curves withseveral constant heating or cooling rates. The rate constants of crystallization obtained from bothisothermal and nonisothermal curves of poly(ethylene terephthalate)were compared.     

DIASTEREOSELECTIVITY OF ALLYBORATION OF ALDEHYDES

Reaction of(Z)-Crotyldiisopinocampheylborane with a series of alde-hydes have been examined,and the ratio of erythro to threo products varies fr-om 20:1 to 1:1.The results are discussed in detail.     

Ag adsorption on Cd-terminated CdS (0 0 0 1) and S-terminated CdS (0 0 0 1?) surfaces: First-principles investigations

First-principles calculations are performed to study the adsorption of Ag at Cd-terminated CdS (0 0 0 1) and S-terminated CdS (0 0 0 1?) surfaces as a function of Ag coverage. Our results reveal that Ag adsorption at Cd-terminated (0 0 0 1) has a large binging energy than at S-terminated (0 0 0 1?) surface. For Ag adsorption at Cd-terminated (0 0 0 1) surface, T4 structure is more favorable and the Ag-Cd bond posses an ionic-like character. While for Ag adsorption at S-terminated (0 0 0 1?) surface, the H3 structure is most stable and the bonding between Ag-S is covalent. It is found that the magnitude and the sign of surface dipole moment are partly determined by the difference between the electronegativities of Ag and the host atom bonding with Ag. The adsorption energy changes as a function of Ag coverage. In addition, related properties of Ag cluster adsorption at Cd-terminated (0 0 0 1) surface are also discussed.     

SINGLE IONIC CONDUCTI0N OF POLYSILOXANE CONTAINING PROPYLENE CARBONATE GROUP AND LITHIUM POLYMERIC SALTS

The polysiloxane containing propylene carbonate side group and several lithium poly-meric salts were synthesized. The structure were confirmed by IR, NMR and XPS. Theblending systems of polysiloxane containing propylene carbonate group with different lithiumpolymeric salts were studied by ion conductivity XPS and DSC. Different lithium poly-meric salts in the blending system lead to conductivity arranged in the following sequence:poly(lithium ethylenebenzene sulfonate methylsiloxane)>poly(lithium propionate methyl-siloxane)>poly(lithium propylsulfonate methylsiloxane)>poly(lithium styrenesulfonate).In the blending system the best single ion conductivity was close to 10~(-5) Scm~(-1) at roomtemperature. XPS showed that at low lithium salt concentration the conductivity increasedwith the increasing content of lithium salt, in consequence of the increase of free ion andsolvent separated ion pair. At high lithium salt concentration the free ion was absent andthe solvent-separated ion pair functioned as carrier.     

FEATURES OF Pb ISOTOPIC COMPOSITION OF ORES AND EVOLUTION OF CONTINENTAL CRUST OF CHINA

Based on the Pb isotopic features, the ore leads in the continent of China can be dividedinto four types: (i) single-stage lead of low μ value derived from mantle, (ii) homogeneouslead of crustal source with high μ value, (iii) modern mixing lead between mantle andcrust, and (iv) residual lead of crustal source. As the leads from mantle had possessed single-stage features (μ = 7.8) before the Proterozoic, the ages of continental crust can be calculatedbased on the mixing Pb of type (iii). The results hidicate that the continental crust of Chinawas mainly generated during the Archaean, and the growth rates of crust reached the max-ima by the ages of 3.3-3.4, 2.6 and 1.6-1.7 b.y. The occurrences of residual crust Pbwith high ~(207)Pb/~(204)Pb and ~(208)Pb/~(204)Pb anomalies were associated with the remelting andreconstruction of crust since 1.6 b.y. ago. The lead sources in the continent of China showhigher Th/U ratios (3.3-6.5) and ~(207)Pb anomalies than those in other continents, indicationthe conti     

MOLECULAR AND CRYSTAL STRUCTURE OF (η~6-BENZOPHENONE)TRICARBONYLCHROMIUM(0)

<正> The crystal of (η6-C6H5C(O)C6H5)Cr(CO)3 belongs to monoclinic system with space group P21/n. The cell parameters are: a=ll.068(2), b= 7.501(2), c=17.174(2) A, β=91.22(2)0, V=1425.4(8) A3, Z=4. The structure was solved by the analysis of 1745 observed reflections recorded on CAD-4 diffractometer. The final R=0.053.