PROPERTIES AND SYNTHESIS OF NEW SUPPORTS FOR IMMOBILIZATION OF ENZYMES BY COPOLYMERIZATION OF VINYLENE CARBONATE AND METHACRYLIC ACID

Methacrylic acid first was neutralized with an aqueous solution of NaOH to pH=6.0～7.0, vinylene carbonate(VCA) was added to the solution, then monomers were copolymerized in paraffin oil by means of reverse-phase suspensionpolymerization and hydrophilic copolymeric supports were prepared. The properties of the supports were determined usingtrypsin and results show that the amount of enzymes coupled to the supports and the specific activity of immobilized trypsinare related to the content of VCA structure units, reaction time and concentration of enzyme solution, etc.     

VISCOMETRIC STUDY OF POLY(METHYL METHACRYLATE) AND POLYSTYRENE BLENDS IN DIFFERENT SOLVENTS

The intermolecular interaction between poly(methyl methacrylate) (PMMA) and polystyrene (PS) intetrahydrofuran (THF) and N,N'-dimethyl formamide (DMF) solvents was studied at 28℃ using a dilute solution viscometrymethod. Solvent is believed to play a key role in characterizing the viscosity behavior of the polymer solution. The intrinsicviscosity and viscosity interaction parameter were experimentally measured for the binary (solvent/polymer) and for theternary systems in two solvents. The compatibility of the polymer mixture was discussed in terms of the sign of △b_m. Theresults show that the compatibility of PMMA/PS blend in DMF is larger than that in THF.     

水菱钇型碳酸钕的形成及聚甘油脂肪酸酯对结晶的影响

Amorphous Neodymium carbonate was prepared by the precipitation reaction of neodymium chloride with ammonium bicarbonate in solution, and then aged at 60 ℃ to form crystalline neodymium carbonate. The feed molar ratio of n_(NH4HCO3)/n_(NdCl3 was 2.5, and the precipitation was carried out with or without addition of polyglyceryl fatty acid ester (PGFAE). The phase type and morphology of crystalline neodymium carbonates were examined by XRD and SEM, and the effect of PGFAE on the crystallization speed was investigated by volume change in deposit layer and in situ pH determination. The content of neodymium and chloride in crystals was analyzed, and the crystallization reaction or crystal growth characteristics were discussed. It was found that all the crystalline neodymium carbonates were tengerite type, and contained less crystalline water and chloride than that of lanthanite type neodymium carbonate crystallized at room temperature, which is beneficial to the production of neodymium carbonate with higher neodymium and lower chloride content. The addition of PGFAE not only could eliminate the foam formed during precipitation, but also could shorten crystallization time, and form large radiative-like shape conglomeration by the irregulative linkage of one dimension needle crystals. It is also suggested that the morphology and the chloride content of neodymium carbonate were dependent on the structure and crystal growth characteristics.     

SYNTHESIS AND CHARACTERISTICS OF POLY(ARYLENE ETHER DIKETONE)S

Poly(arylene ether diketone)s were prepared by the aromatic nucleophilicdisplacement reaction of 4,4'-difluorobenzil with different bisphenols in the presence of an-hydrous potassium carbonate in diphenylsulfone at elevated temperature. The polymersobtained had inherent viscosity of 0.51 ～ 0.63 dL/g, and exhibited glass transition temper-ature ranging from 136 ～217℃ mainly depending on the bisphenols used in the polymersynthesis. Thermogravimetry of these polymers showed excellent thermal stability, indi-cating that 10% weight losses of the polymers were observed in the range above 428℃ and438℃ in air and nitrogen, respectively. The mechanical properties of these polymers werealso described and the permeability of five polymers for H_2, O_2 and N_2 was determined at30℃.     

A New Process for Synthesis of Dimethyl Carbonate from Ethylene Carbonate and Methanol without any Catalyst under Supercritical Conditions

Dimethyl carbonate was synthesized by transesterification reaction between ethylene carbonate and methanol under supercritical conditions without any catalyst. Experimental results showed that the residence time and the molar ratio of methanol to ethylene carbonate all can affect the conversion of ethylene carbonate. When the molar ratio of methanol to ethylene carbonate was 8:1, 81.2% conversion can be achieved at 9.0 MPa and 250℃ after 8 h.     

Fully Biodegradable Poly(lactic acid)/Poly(propylene carbonate) Shape Memory Materials with Low Recovery Temperature Based on <Emphasis Type="Italic">in situ</Emphasis> Compatibilization by Dicumyl Peroxide

Fully biodegradable blends with low shape memory recovery temperature were obtained based on poly(lactic acid) (PLA) and poly(propylene carbonate) (PPC).By virtue of their similar chemical structures,in situ cross-linking reaction initiated by dicumyl peroxide (DCP) between PLA and PPC chains was realized in PLA/PPC blends.Therefore,the compatibility between PLA and PPC was increased,which obviously changed the phase structures and increased the elongation at break of the blends.The compatibilized blends had a recovery performance at 45 ℃.Combining the changes of phase structures,the mechanism of the shape memory was discussed.It was demonstrated that in situ compatibilization by dicumyl peroxide was effective to obtain eco-friendly PLA/PPC blends with good mechanical and shape memory properties.     

Synthesis via Precursor Method and Shape Evolution of Basic Magnesium Carbonate

Basic magnesium carbonate(4 MgCO3·Mg(OH)2·4 H2 O) with spherical-like structure was synthesized through precursors thermal decomposition. The precursor of magnesium carbonate trihydrates(MgCO3·3 H2 O) was synthesized by brine and ammonium bicarbonate, and the thermal decomposition conditions were investigated in detail. The obtained particulate was characterized using SEM, XRD and laser particle analyzer. The result showed that it was easy to obtain spherical-like 4 MgCO3·Mg(OH)2·4 H2 O by precursor thermal decomposition at 80~100 ℃ with thermal decomposition time 90 min, stirring time 15 min and the liquid initial concentration 0.1 mol/L, while rod-like 4 MgCO3·Mg(OH)2·4 H2 O with a surface of "house of card" structure was more likely to be obtained at low temperature(55 ℃), and rosette-like products were obtained at a little higher temperature(80 ℃) by direct synthesis.     

An approach to synthesis of (Z)-2-chloro-1,3-diarylpropen-1-ones by Vilsmeier reagent (bis-(trichloromethyl) carbonate/DMF)

A series of(Z)-2-chloro-1,3-diarylpropen-1-ones were unexpectedly synthesized in moderate yields by treatment of easily available 2,3-epoxy-1,3-diarylpropan-1-ones with Vilsmeier reagent,which was derived from bis(trichloromethyl) carbonate(BTC, triphosgene) and DMF.A possible mechanism was also proposed,where sequential ring-opening,halogenation and elimination reactions were involved.     

SILICON-CONTAINING POLY(p-ARYLENE VINYLENE)S:SYNTHESIS AND PHOTOPHYSICS

A series of new silicon-containing poly(p-arylene vinylene)s(PAVs)with anthracene units in the main chain were synthesized by hydrosilylation reaction.The introduction of organosilicon units improved the solubility of the polymers,and theπ-πconjugation of polymeric chains was interrupted.These polymers behaved as blue-green light emitters with their fluorescence maximum at 447—499 nm and quantum yields in the range of 0.28-0.30 in solution.     

A New Technique of Synthesizing 10—Hydroxy—5—methyl—5,10—dihydrophenophosphazine 10—Oxide

10-Hydroxy-5-methyl-5,10-dihydrophenophosphazine 10-oxide(1)was prepared by a new technique of treating 10-methoxy-5,10-dihydrophenophosphazine 10-oxide(2)with an equivalent of NaH in anhydrous DMF,and then at 120℃ for 3-4h,which not only avoided poisonous and expensive methyl iodide used in literature,but made the consumption of NaH greatly decrease as well.The possible reaction mechanism was also described.The chemical structure of 1 was confiremed by IR,NMR,and mass spectroscopy.     

Synthesis and Thermal Crosslinking Behavior of Poly（aryl ether ketone）s Containing 1,4-Naphthalene Moieties

A new monomer, 1,4-bis(4-fluorobenzoyl) naphthalene (compound 2) was synthesized via a two-step reaction. 1,4-Naphthalenedicarboxylic acid chloride (compound 1) was prepared by using the acyl chlorization reaction of 1,4-naphthalenedicarboxylic acid with thionyl chloride. The Friedel-Crafts acylation of compound 1 with fluorobenzene afforded compound 2 in a 80% yield. The polycondensation of compound 2 with various bisphenols in tetramethylene sulfone(TMS) in the presence of excess potassium carbonate as a condensation reagent was carried out at 210℃ to quantitatively afford the corresponding poly(aryl ether ketone)s (compounds 3-8) containing 1,4-naphthalene moieties. Thermal analyses showed that the polymers have Tg values ranging from 496 to 500 K and are thermally stable in air with initial mass loss above 500℃. These novel polymers exhibited an excellent solubility in organic solvents including NMP, DMAc, and chloroform, etc. In addition, the glass transition temperatures of these polymers increased and the polymers became insoluble in chloroform after treated at 260℃, indicating the occurrence of a thermal crosslinking reaction.     

A General, Highly Efficient Ullmann C-O Coupling Reaction under Microwave Irradiation and the Effects of Water

A general, rapid and highly efficient method for the synthesis of diaryl ethers under the assistance of microwave irradiation was described. A series of diaryl ethers were prepared by direct coupling of phenols and aryl halides in good to excellent yields in anhydrous DMF or NMP at 150 ℃ within 20 rain. The presence of water was found to have a significant impact on the Ullmann C-O coupling reaction between aryl halides and phenols under microwave irradiation.     

An unusual isotopic fractionation of boron in synthetic calcium carbonate precipitated from seawater and saline water

Inorganic calcium carbonate precipitation from natural seawater and saline water at various pH values was carried out experimentally. The results show the clear positive relationships between boron concentration and δ11B of inorganic calcium carbonate with the pH of natural seawater and saline water. However, the variations of boron isotopic fractionation between inorganic calcite and seawater/saline water with pH are inconsistent with the hypothesis that B(OH)4- is the dominant spe-cies incorporated into the biogenic calcite structure. The isotopic fractionation factors α between synthetic calcium carbonate precipitate and parent solutions increase systematically as pH increases, from 0.9884 at pH 7.60 to 1.0072 at pH 8.60 for seawater and from 0.9826 at pH 7.60 to 1.0178 at pH 8.75 for saline water. An unusual boron isotopic fractionation factor of larger than 1 in synthetic calcium carbonate precipitated from seawater/saline water at higher pH is observed, which implies that a substantial amount of the isotopically heavier B(OH)3 species must be incorporated preferentially into synthetic inorganic carbonate. The results propose that the incorporation of B(OH)3 is attributed to the formation of Mg(OH)2 at higher pH of calcifying microenvironment during the synthetic calcium carbonate precipitation. The preliminary experiment of Mg(OH)2 precipitated from artificial seawater shows that heavier 11B is enriched in Mg(OH)2 precipitation, which suggests that isotopically heavier B(OH)3 species incorporated preferentially into Mg(OH)2 precipitation. This result cannot be applied to explain the boron isotopic fractionation of marine bio-carbonate because of the possibility that the unusual environment in this study appears in formation of marine bio-carbonate is infinitesimal. We, however, must pay more attention to this phenomenon observed in this study, which accidentally appears in especially natural environment.     

Determination of sulfur anions by ion chromatography-postcolumn derivation and UV detection

A novel method for determination of formaldehyde sulfoxylate,sulfite,thiocyanate,and thiosulfate in foodstuffs by ion chromatography separation with postcolumn derivation and UV detection has been developed.All species are separated at Dionex IonPac AG22A and AS22A with mobile phase of a mixture of 4.5 mmol/L sodium carbonate and 0.8 mmol/L sodium bicarbonate at a flow-rate of 1.0mL/min.The postcolumn derivation solution was 0.24%iodine in 0.2%phosphate acid and the detection wavelength was set at 288 nm...     

SYNTHESIS AND REACTIONS OF BIS（β—ALKOXY—ETHYL CYCLOPENTADIENYL）TITANOUM（ZIRCONIUM）DICHLORIDES

Bis(β-alkoxy-ethyl cyclopentadienyl) titanium (zirconium) dichlorides was newly synthe-sized,and through interfacial polycondensation of bis(β-alkoxy-ethyl cyclopentadienyl) titanium dichlorides with diacids,diphenols,and hydroxy-acids,a series of new titanium polymers were prepared.The polymers obtained are yellow in color,having mol. wts between 10^3-10^6.They possess heat-resistant properties and show better solubilities that Carraher′s series.Thus,TG/DTG determinations showed that while suffering initial loss of wts. at around 260℃-470℃,they remain stable at 600-800℃.Residual wts.are around 50% of the initial at 947.5℃.They are soluble in glacial acetic acid,DMAC,DMF,and DMSO.     

SYNTHESIS OF POLY（3,4-AZOPYRIDYLENE） AND OXYGEN-BINDING AFFINITY OF ITS COMPLEX WITH COBALTPORPHYRIN

Synthesis and characteristics of poly(3,4-azopyridylene) (PAP), conductivity and oxygen-binding affinity of its complex with meso-α,α,α,α-tetrakis(o-pivalamidophenyl) porphyrinatocobalt(Ⅱ) (CoP) were studied. PAP was prepared by oxidative polymerization of 3,4-diaminopyridine (DAP) in DMF solution using CuCl/pyridine as the catalyst. IR and NMR results showed that the peak of amido group in DAP was converted to the azo group in PAP and a π conjugated polymer was synthesized. The average molecular weight of PAP was determined to be 5.0 × 103. The PAP-CoP complex was prepared by complexing the pyridyl group of PAP with the fifth coordination site of CoP in DMF solution. In comparison with the CoP complex with a non-π conjugated polymer, the PAP-CoP complex shows good electroconductivity of 5.8 × 10-6 Scm-1. The PAP-CoP complex displays a reversible change in the UV-Visible absorption spectrum from the deoxy form to the oxy or oxygen-binding one with an isosbestic point, in response to the partial oxygen pressure of the atmosphere. The oxygen-response behavior was monitored at the absorbance ascribed to the oxy form at 548 nm to give the oxygen-binding affinity.The oxygen-binding equilibrium curves of PAP-CoP complex obey a Langmuir isotherm. DMF has great effects on the oxygen-binding properties of the PAP-CoP complex. The oxygen-binding affinity of PAP-CoP complex in the solid state is higher than that in DMF solution. With decreasing temperature, the oxygen-binding affinity of the PAP-CoP complex increases.     

Carbon Dioxide Fixation Method for Electrosynthesis of Benzoic Acid from Chlorobenzene

Carbon dioxide fixation technique was developed as an alternative dechlorination method of chlorobenzenes.Electrolysis of chlorobenzene was carried out in a one-compartment cell fitted with an alu- minium anode and a platinum cathode.Electrolysis in N,N-dimethylformamide(DMF)solution contain- ing 0.1 M of tetrapropylammonium bromide(TPAB)at 0℃,100 ml/min of CO_2 flow rate and 120 mA/cm~2 of current density was found to be the optimum conditions of this electrocarboxylation,which gave 72% yield of benzoic acid from chlorobenzene.These conditions were then applied to 1,2-dichlorobenzene and 1,3-dichlorobenzene in order to convert them to their corresponding benzoic acids.     

Structure-Activity Correlations of Calcined Mg-Al Hydrocalcites for Aliphatic Polycarbonate Synthesis via Transesterification Process

Mg-Al mixed oxides with different Mg/Al molar ratio were prepared by thermal decomposition of hydrotalcitelike precursors at 500℃ for 5.0 h and used as catalysts for the transesterification of diphenyl carbonate with 1,4-butanediol to synthesize high-molecular-weight poly(butylene carbonate)(PBC). The structure-activity correlations of these catalysts in this transesterification process were discussed by means of various characterization techniques. It was found that the chain growth for the formation of PBC can only be obtained through connecting ―OH and ―OC(C)OC_6H_5 end-group upon removing the generated phenol, and the sample with Mg/Al molar ratio of 4.0 exhibited the best catalytic performance, giving PBC with M_w of 1.64 × 10~5 g/mol at 210 ℃ for 3.0 h. This excellent activity depended mainly on the specific surface area and basicity rather than pore structure or crystallite size of MgO.     

VISCOMETRIC INVESTIGATIONS OF POLYVINYLPYRROLIDONE IN MIXED SOLVENTS AND WITH VARYING TEMPERATURE

The viscosity behavior of polyvinylpyrrolidone (PVP) has been determined at 25℃ in mixed solvents comprising water/dimethylformamide (DMF) and water /methanol (MeOH). Analysis of the data has considered the PVP as being both host and guest polymer in solution. The intrinsic viscosity of PVP in DMF is higher than in water and in MeOH, but also increases in a mixed solvent with high water content because of the effect of polymer-solvent interactions. It was also found that the intrinsic viscosity of PVP at finite concentration, [ηpvp]c decreases with an increase in the concentration of PVP in solution. The viscosity behavior of PVP in a mixed solvent is affected by the concentration-dependent intermolecular excluded volume effect, which can be quantitatively expressed by the parameter, bY, which reflects the shrinkage of PVP chain coils, resulting in a decrease of [ηpvp]c. The effect of temperature on the viscosity behavior of PVP in MeOH shows that the interaction parameter increases up to a maximum value, and then decreases after a certain temperature.     

Fully Biodegradable Poly(lactic acid)/Poly(propylene carbonate) Shape Memory Materials with Low Recovery Temperature Based on in situ Compatibilization by Dicumyl Peroxide

Fully biodegradable blends with low shape memory recovery temperature were obtained based on poly(lactic acid)(PLA) and poly(propylene carbonate)(PPC). By virtue of their similar chemical structures, in situ cross-linking reaction initiated by dicumyl peroxide(DCP) between PLA and PPC chains was realized in PLA/PPC blends. Therefore, the compatibility between PLA and PPC was increased, which obviously changed the phase structures and increased the elongation at break of the blends. The compatibilized blends had a recovery performance at 45 °C. Combining the changes of phase structures, the mechanism of the shape memory was discussed. It was demonstrated that in situ compatibilization by dicumyl peroxide was effective to obtain eco-friendly PLA/PPC blends with good mechanical and shape memory properties.