活性自由基聚合法制备以C60封端的聚苯乙烯

通过活性自由基聚合的方法制备了以２,２,６,６－四甲基－４－羟基呱啶氮氧自由基（ＴＥＭＰＯＬ）封端的聚苯乙烯大分子,实验结果证明该反应体系是一个典型的活性自由基聚合体系,同时研究了ＴＥＭＰＯＬ／ＡＩＢＮ的比例及ＡＩＢＮ的含量对聚合反应的影响。用以ＴＥＭＰＯＬ封端的聚苯乙烯和Ｃ６０反应,制得了Ｃ６０的聚苯乙烯高分子衍生物,紫外和ＧＰＣ结果均证明Ｃ６０已连接到聚苯乙烯的长链上,ＧＰＣ的结果还证明,Ｃ６     

PREPARATION AND CATALYTIC HTDROGENATION BEHAVIOUR OF POLYMERIC PORPHYRIN－PALLADIUM COMPLEX

ＰＲＥＰＡＲＡＴＩＯＮ　ＡＮＤ　ＣＡＴＡＬＹＴＩＣ　ＨＴＤＲＯＧＥＮＡＴＩＯＮ　ＢＥＨＡＶＩＯＵＲ　ＯＦ　ＰＯＬＹＭＥＲＩＣ　ＰＯＲＰＨＹＲＩＮ－ＰＡＬＬＡＤＩＵＭ　ＣＯＭＰＬＥＸＰＲＥＰＡＲＡＴＩＯＮＡＮＤＣＡＴＡＬＹＴＩＣＨＴＤＲＯＧＥＮＡＴＩＯ...     

COMPUTERIZED PREDICTION AND SYNTHESIS OF TERNARY COMPOUND ZKBr 3MnSO_4

ＣＯＭＰＵＴＥＲＩＺＥＤ　ＰＲＥＤＩＣＴＩＯＮ　ＡＮＤ　ＳＹＮＴＨＥＳＩＳ　ＯＦ　ＴＥＲＮＡＲＹ　ＣＯＭＰＯＵＮＤ　２ＫＢｒ　３ＭｎＳＯ_４ＣＯＭＰＵＴＥＲＩＺＥＤＰＲＥＤＩＣＴＩＯＮＡＮＤＳＹＮＴＨＥＳＩＳＯＦＴＥＲＮＡＲＹＣＯＭＰＯＵＮＤＺＫＢｒ?..     

可生物降解的聚乳酸弹性体的合成与表征

本文将丙交酯（ＤＬ－ＬＡ）与聚乙二醇（ＰＥＧ）的预聚体用甲苯－二异氰酸酯８０（ＴＤＩ）扩链，得到了一系列的聚乳酸（聚醚）型聚氨酯（ＰＥＧ－ＰＬＡ／ＰＵ）弹性体。对预聚体和弹性体分别进行了ＩＲ、ＨＮＭＲ和ＤＭＡ表征，并测定了弹性体的力学性能。结果表明，ＬＡ与ＰＥＧ生成的预聚体是一种三嵌段结构：ＨＯ－ＰＬＡ－ＰＥＧ－ＰＬＡ－ＯＨ。随着ＰＥＧ含量的增加，弹性体的玻璃化温度下降；ＰＥＧ分子量增大时，弹性体     

STUDIES ON SEPARATION AND DETERMINATION OF THE COUMARINS IN MURRAYA PANICULATA（L）JACK BY RP－HPLC

ＳＴＵＤＩＥＳ　ＯＮ　ＳＥＰＡＲＡＴＩＯＮ　ＡＮＤ　ＤＥＴＥＲＭＩＮＡＴＩＯＮ　ＯＦ　ＴＨＥ　ＣＯＵＭＡＲＩＮＳ　ＩＮ　ＭＵＲＲＡＹＡ　ＰＡＮＩＣＵＬＡＴＡ（Ｌ）ＪＡＣＫ　ＢＹ　ＲＰ－ＨＰＬＣＳＴＵＤＩＥＳＯＮＳＥＰＡＲＡＴＩＯＮＡＮＤＤＥＴＥＲＭＩ...     

PARAMAGNETIC AND DIAMAGNETIC DICOPPER（Ⅱ） COMPLEXES WITH DI－SCHIFF BASE DERIVED FROM 2－HYDROXY－1－NAPHTHALDEHYDE AND1，3－DIANINO－2－PROPANOL

ＰＡＲＡＭＡＧＮＥＴＩＣＡＮＤＤＩＡＭＡＧＮＥＴＩＣＤＩＣＯＰＰＥＲ（Ⅱ）ＣＯＭＰＬＥＸＥＳＷＩＴＨＤＩ－ＳＣＨＩＦＦＢＡＳＥＤＥＲＩＶＥＤＦＲＯＭ２－ＨＹＤＲＯＸＹ－１－ＮＡＰＨＴＨＡＬＤＥＨＹＤＥＡＮＤ１，３－ＤＩＡＮＩＮＯ－２－ＰＲＯＰＡＮＯＬ...     

IR研究聚氨酯预聚反应的活化能

在滴定分析判断聚乙二醇（ＰＥＧ）和２，４－二甲苯二异氰酸酯（ＴＤＩ）预聚反应为一级反应的基础上，用ＩＲ分析ＰＥＧ和ＴＤＩ预聚反应过程中ＮＣＯ基的定量变化，结合Ａｒｒｈｅｎｉｕｓ经验式得ＰＥＧ入ＴＤＩ预聚反应的表观活性能Ｅα＝８６．９ｋＪｍｏ６－２，为研究其预聚反应的历程奠定基础。     

BETA－CORRECTION SPECTROPHOTOMETR DETERMINATION OF COPPER ITS CHELATE＇S CHARACTERISTIC PAPAMETERS WITH o－IODOBENZENEDIAZOAMINOBENZENE－p－AZOBENZENE

ＢＥＴＡ－ＣＯＲＲＥＣＴＩＯＮ　ＳＰＥＣＴＲＯＰＨＯＴＯＭＥＴＲ　ＤＥＴＥＲＭＩＮＡＴＩＯＮ　ＯＦ　ＣＯＰＰＥＲ　ＩＴＳ　ＣＨＥＬＡＴＥ＇Ｓ　ＣＨＡＲＡＣＴＥＲＩＳＴＩＣ　ＰＡＰＡＭＥＴＥＲＳ　ＷＩＴＨ　ｏ－ＩＯＤＯＢＥＮＺＥＮＥＤＩＡＺＯＡＭＩＮＯ...     

PREPARATION AND CHARACTERIZATON OF MICROPOROUS CATALYTIC MATERIALS WITH NARROW PORE DISTRIBUTION AND HIGHLY DISPERSED PALLADIUM

ＰＲＥＰＡＲＡＴＩＯＮＡＮＤＣＨＡＲＡＣＴＥＲＩＺＡＴＯＮＯＦＭＩＣＲＯＰＯＲＯＵＳＣＡＴＡＬＹＴＩＣＭＡＴＥＲＩＡＬＳＷＩＴＨＮＡＲＲＯＷＰＯＲＥＤＩＳＴＲＩＢＵＴＩＯＮＡＮＤＨＩＧＨＬＹＤＩＳＰＥＲＳＥＤＰＡＬＬＡＤＩＵＭ￥ＡｎＷｕＬｉ；ＧｕｏＸ...     

SYNTHESIS OF POLYSUBSTITUTED AROMATIC COMPOUNDS：2．THE DIELS－ALDER REACTION OF 1－CHLORO SUBSTITUTED DIENES WITH DIMETHYL ACETYLENEDICARBOXYLATE

ＳＹＮＴＨＥＳＩＳＯＦＰＯＬＹＳＵＢＳＴＩＴＵＴＥＤＡＲＯＭＡＴＩＣＣＯＭＰＯＵＮＤＳ：２ＴＨＥＤＩＥＬＳ－ＡＬＤＥＲＲＥＡＣＴＩＯＮＯＦ１－ＣＨＬＯＲＯＳＵＢＳＴＩＴＵＴＥＤＤＩＥＮＥＳＷＩＴＨＤＩＭＥＴＨＹＬＡＣＥＴＹＬＥＮＥＤＩＣＡＲＢＯＸＹＬ...     

Fluoropolyethers end‐capped by polar functional groups. I. Kinetic approach to the reaction of hydroxy‐terminated fluoropolyethers with cycloalyphatic and aromatic diisocyanates

Urethane reactions of cycloaliphatic and aromatic diisocyanates with hydroxy‐terminated fluoropolyethers (FPEs) of various molecular weights and structure, at NCO : OH = 2, have been studied by monitoring, by IR analysis, the rate of decrease in NCO absorbance at 2264–2268 cm⁻¹. Different diisocyanates have been tested, among them the following: 4,4′‐dicyclohexylmethane diisocyanate (H₁₂MDI); 5‐isocyanato‐1,3,3‐trimethylcyclohexylmethyl isocyanate or isophorone diisocyanate (IPDI); 2,4‐toluene diisocyanate (TDI). Ethyl acetate (EA), methyl isobutyl ketone (MIBK), and hexafluoroxylene (HFX) have been used as solvents in presence of dibutyltin dilaurate (DBTDL) or 1,4‐diazabicyclo[2.2.2]octane (DABCO) as catalysts. These reactions gave rise to NCO‐end‐capped FPE–oligourethanes. Preliminary solubility tests for HO‐terminated FPEs in various solvents made it possible to select proper candidates for carrying out reaction in homogeneous conditions at high concentrations of reagents (30–50% w/w). The second‐order kinetic mechanism was shown to be valid. Positive deviations from linearity for the second‐order kinetics around 40–80% conversion, found for most of the FPE diols, were attributed to the autocatalysis of the isocyanate–hydroxyl reaction by the arising urethane groups. Uncatalyzed reactions with cycloaliphatic diisocyanates are very slow at 40°C. The tertiary amine DABCO is a much less effective catalyst than DBTDL. FPEs having terminal OH groups separated from the perfluorinated main molecular chain by  (OCH₂CH₂)_n segments (n = 1–2) are generally more reactive than FPEs with end  CH₂OH groups. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 557–570, 1999     

Preparation of polyurethane dispersions by miniemulsion polymerization

With a two‐step miniemulsion polymerization, hydrophobic polyurethane (PU) dispersions were prepared with a cosurfactant, the costabilizer hexadecane (HD) in the oil phase, and sodium dodecyl sulfate (SDS) in the water phase. The first step involved the formation of NCO‐terminated prepolymers between isophorone diisocyanate and poly(propylene glycol) oligomer in toluene. Next, PU dispersions were produced by a miniemulsion method in which an oil phase containing NCO‐terminated prepolymers, HD, the chain extender 1,4‐butanediol (BD), the crosslinking agent trimethylol propane (TMP), and the catalyst dibutyltin dilaurate was dispersed in the water phase containing SDS. The influence of experimental parameters, such as the ultrasonication time, concentrations of SDS and HD, and TMP/BD and NCO/OH equivalent ratios, on the sizes of the miniemulsion droplets and polymer particles, as well as the molecular weights and thermal properties of the PU polymer, was examined. The chemical structure of the produced PU polymer was identified with a Fourier transform infrared spectrometer. The molecular weight distribution and average particle size were measured through gel permeation chromatography and dynamic light scattering, respectively. The thermal stability of the PU polymer was characterized with thermogravimetric analysis. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 4870–4881, 2005     

Efficacy of clay content and microstructure of curing agents on the structure–property relationship of new‐generation polyurethane nanocomposites

The physicomechanical properties of new polyurethanes (PUs) derived from toluene diisocyanate, poly(propylene glycol), and cured by third‐generation hyperbranched polyester polyol (HB3), trimethylolpropane (TMP), or glycerol and their nanocomposites have been investigated. An apparent microphase‐segregated morphology of PU nanocomposites cured by HB3 has been observed by transmission electron microscopy and atomic force microscopy. Morphological studies reveal regions of mostly exfoliated and some intercalated morphology in the case of the nanocomposites, which have been further ascertained by X‐ray diffraction analysis. The HB3‐cured PU nanocomposite containing 8 wt% of modified montmorillonite (Cloisite 30B) clay shows approximately 140% increase in tensile strength along with improvement in thermal and dynamic mechanical properties in comparison with the control hyperbranched PU. It has also been found from Fourier transform infrared spectroscopy analysis that the extent of tethering reactions between the polymer chains carrying residual –NCO groups and the reactive hydroxyl (?OH) groups of HB3 is significant, and the nanofiller has been found to preferentially react with the –NCO group of the prepolymer. Furthermore, the properties of HB3‐cured PU have been compared with the glycerol and TMP‐cured PUs and their nanocomposites. The physicomechanical and thermal properties for nanocomposites of HB3‐cured PUs are superior to those of the conventionally cured PUs. Copyright © 2011 John Wiley & Sons, Ltd.     

Theoretical study on the reaction mechanism of the alcoholysis of isocyanates

In this paper, the reactions of HNCO or CH₃NCO with methanol have been studied using the ab initio MO method. The geometries of the reactants and products have been optimized by the energy gradient method. The calculated results are in accordance with experiment. Using Powell's method, by the minimization of the Euclidean norm σ of the gradient, the structures of the transition state (TS ) for the two reactions were obtained. The structures have been further confirmed as TS by finding that there is one and only one negative eigenvalue for their force constant matrix. The imaginary vibration mode corresponding to the TS was also discussed. The calculated activation barriers of these two reactions are 96.02 and 95.13 kJ/mol, respectively. It can be concluded that the alcoholysis reaction of isocyanate is a nucleophilic addition reaction with methanol as an electronic donor and isocyanate as an acceptor and that the hydroxyl hydrogen of CH₃OH plays an important role in the reaction.     

Theoretical studies of the hydroxide-catalyzed P-O cleavage reactions of neutral phosphate triesters and diesters in aqueous solution: examination of the changes induced by H/Me substitution

DFT calculations and dielectric continuum methods have been employed to map out the lowest activation free-energy profiles for the alkaline hydrolysis of representative phosphate triesters and diesters, including trimethyl phosphate (TMP), dimethyl 4-nitrophenyl phosphate (DMNPP), dimethyl hydrogen phosphate (DMHP), and the dimethyl phosphate anion (DMP-). The reliability of the calculations is supported by the excellent agreement observed between the calculated and the experimentally determined activation enthalpies for phosphate triesters with poor (TMP) and good (DMNPP) leaving groups. The results obtained for the OH- + DMHP and OH- + DMP- reactions are also consistent with all the available experimental information concerning the hydrolysis reaction of dimethyl phosphate anion at pH > 5. By performing geometry optimizations in the dielectric field (epsilon = 78.39), we found that OH- can attack the phosphorus atom of DMHP without capturing its proton only if the O-H bond of DMHP is oriented opposite the attacking OH- group. In these conditions, the rate for OH- attack on DMHP was found to be approximately 10(3)-fold faster than that for OH- attack on TMP. The calculated rate acceleration induced by the phosphoryl proton corresponds to the maximum rate effect expected from kinetic studies. Overall, our calculations performed on the dimethyl phosphate ester predict that, contrary to what is generally observed for RNA and aryl phosphodiesters, the water-promoted P-O cleavage reaction of DNA should dominate the base-catalyzed reaction at pH 7. These results are suggestive that nucleases may be less proficient as catalysts than has recently been suspected.     

A review of kinetic studies on the formation of interpenetrating polymer networks

Interpenetrating polymer networks (IPNs) are unique alloys of crosslinked polymers. This article reviews the studies on kinetic effects involved in IPN formation. Several investigators have studied the effect of kinetics of curing reactions on the morphology and properties of IPNs. It was found, in general, that the faster the rates of the respective chain extension and crosslinking reactions are and the closer they are to simultaneity, the more homogeneous are the IPNs. Other investigations revealed that the individual components sometimes can polymerize more rapidly in the IPN than alone, due to a “solvent effect” of the IPN. Effects of changing reaction variables, such as NCO/OH ratio, composition activators and temperature were used to study reaction kinetics as well as phase morphology by the Fourier transform infrared technique. Thermochemical techniques have been utilized to study the kinetics of IPN formation which influence phase separation. Small-angle X-ray scattering and small-angle neutron scattering techniques were used to estimate the extent of microheterogeneity of the phase domains in a study of the kinetics of phase separation in the IPNs.     

Investigations of morphology of moisture‐cured silicone–urethanes

Results of studies on synthesis and properties of siloxane–urethane prepolymers as well as on selected properties of moisture‐cured silicone–urethanes have already been published. In this paper, some results of investigations of the effect of chemical structure of such silicone–urethane polymers on their phase seggregation investigated using mainly (TEM) transmission electron microscopy and small‐angle x‐ray scattering (SAXS) techniques are presented. It was found in TEM studies that in silicone‐urethanes obtained by moisture‐curing of NCO‐terminated prepolymers prepared from siloxane oligomer diols (SOD) and isophoronediisocyanate (IPDI), two factors determine the morphology of samples: length of siloxane chain and NCO/OH ratio. SAXS investigations showed that these silicone–urethanes had a lamellar structure. It was found that the long period of this structure changed from 4 to 9 nanometers as the siloxane chain length increased nine times. The increase of the long period correlated with the decrease of Young's modulus of the corresponding samples. TEM investigations of silicone–urethanes obtained by moisture‐curing of NCO‐terminated prepolymers prepared from the blends of SOD and polyoxypropylenediol (PPG) revealed complex morphology which depended on the SOD/PPG ratio. Copyright © 2000 John Wiley & Sons, Ltd.     

Investigations on anticorrosive,thermal, and mechanical properties of conducting polyurethanes with tetraaniline pendent groups

This article describes the synthesis of conducting hybrid polyurethanes from novel tetraaniline‐diol as Gly‐TAni (glycidol with TAni). A new diol Gly‐TAni has been synthesized in a simple process using tetraaniline (TAni) and glycidol via SN2 reaction in a single‐step process. The asymmetric diol (Gly‐TAni) and polyols (PTMEG and TMP) were reacted with isophorone diisocyanate at OH:NCO ratio of 1:1.2 to obtain ―NCO terminated hybrid conducting polyurethanes. These were subjected for curing under atmospheric moisture to obtain conducting polyurethane‐urea coatings. The conducting coatings showed considerable enhancement in thermal and mechanical stabilities. All these conducting coatings films showed excellent corrosion resistance (on mild steel electrode) with an increase in the percentage of Gly‐TANi (5 to 15 wt%). The films of these hybrid polyurethanes containing pendent tetraanilines showed good surface conductivity in the range of 3.69 × 10⁻⁴ to 2.21 × 10⁻³ S/cm. The electrochemical investigation showed 2 single electron oxidation and 2 single reductions reversibly, centred around tetraaniline segments present in the polymer.     

From NMP to RAFT and Thiol‐Ene Chemistry by In Situ Functionalization of Nitroxide Chain Ends

A straightforward, novel strategy based on the in situ functionalization of polymers prepared by nitroxide‐mediated polymerization (NMP), for the use as an extension toward block copolymers and post‐polymerization modifications, has been investigated. The nitroxide end group is exchanged for a thiocarbonylthio end group by a rapid transfer reaction with bis(thiobenzoyl) disulfide to generate in situ reversible addition–fragmentation chain transfer (RAFT) macroinitiators. Moreover, not only have these macroinitiators been used in chain extension and block copolymerization experiments by the RAFT process but also a thiol‐terminated polymer is synthesized by aminolysis of the RAFT end group and subsequently reacted with dodecyl vinyl ether by thiol‐ene chemistry.     

Thermal and viscoelastic properties of polyurethane-imide/clay hybrid coatings

This paper reports the synthesis and characterization of polyurethane (PU)-imide/clay hybrid coatings based on two types of polyester (PE) polyols (PE-1 and PE-2). PE-1 was prepared from neopentyl glycol (NPG), adipic acid (AA) and isophathalic acid (IPA), whereas PE-2 contains NPG, AA, IPA and TMP (trimethylol propane) with the same hydroxyl value 280 as PE-1. Cetyl trimethyl ammonium bromide (CTAB) modified montmorillonite (K10) was used as the organoclay for the synthesis of the hybrid coatings. The organoclay particles (3 wt%) were well-dispersed into the PE matrix by ultrasonication method. Then the isocyanate terminated PU prepolymers were synthesized by the reaction of polyester polyols with hard segments such as 2,4-toluene diisocyanate (TDI) or isophorone diisocyanate (IPDI) in different NCO/OH ratios e.g., 1.6:1, 2:1 and 3:1, respectively. Finally the thermally stable imide rings were incorporated into the PU backbone by complete reaction of excess NCO content present in the PU prepolymer with pyromellitic dianhydride (PMDA). The thermogravimetric analysis (TGA) shows a higher thermal stability for the PU-imide hybrid coatings with respect to the corresponding PU-imide films. A higher NCO/OH ratio has resulted in higher thermal stability. The activation energies of degradation were calculated by the Broido and Coats-Redfern methods, respectively. The dynamic mechanical thermal analysis (DMTA) results show an enhancement in the glass transition temperature value (T_g) for the clay containing hybrid coatings. The surface analysis by angle resolved X-ray photoelectron spectroscopy (AR-XPS) showed an enrichment of the soft segment towards the surface, and an enhancement in the hard segment composition in the hybrid coatings, resulted in phase mixing.