苯乙烯—二乙烯苯共聚反应中支化行为的研究

本文以粘度为主，研究了苯乙烯（Ｓｔ）－二乙烯苯（ＤＶＢ）自由基交联共聚反应高分子的支化行为，测定了支化参数Ｇ随反应时间ｔ的变化关系。Ｇ随聚合反应的进行呈线性下降，经拟合，在本实验条件下，Ｇ随ｔ变化的这量表达式为Ｇ＝－０．２５ｔ＋１．４５。这为深入认识反应过程及其对产品性能的影响提供了科学数据。     

苯乙烯—二乙烯苯自由基共聚反应动力学研究

本文用气相色谱、激光拉曼、激光散射、ＧＰＣ以及粘度等方法研究了苯乙烯—二乙烯苯的自由基交联共聚反应．求得聚合反应初期的表现速率常数Ｋｓｔ、Ｋｍ－ＤＶＢ及Ｋｐ－ＤＶＢ分别为１．６８×１０－２（小时－１）、３．４３×１０－２（小时－１）及５．５４×１０－２（小时－１）；从悬挂双键含量变化解释分子内环化推迟了凝胶化点；由跟踪检测反应中分子重量、尺寸变化指出宏观尺寸分子的出现使重均分子量（）在凝胶化点发散；讨论了多分散、支化对分子尺寸Ｒｇ（均方旋转半径）、Ｒｈ（流体力学半径）的影响，定量关系为：δ＝Ｒｇ／Ｒｈ＝０．００６１ｅｘＰ（１．４３２ｔ）；拟合了Ｒｈ对反应时间的指数依赖性ＲＡ＝５．１９５ｅｘｐ（０．８７２ｔ），这证实了凝胶化点前属反应控制机理。     

孔雀石绿增感聚苯乙炔的光导体

采用电位放电技术研究孔雀石绿（ＭＧ）增感顺式聚苯乙炔（ｃｔ－ＰＰＡ）光导体的光敏性，发现孔雀石绿是顺式聚苯乙炔新的有效增感剂。以Ａｌ／ｃｔ－ＰＰＡ：ＭＧ：ＰＣ（１００：５：１０）（１～１．５μｍ）／ＰＶＫ：ＴＰＡ：ＰＣ（１０：１０：１）（１５～２０μｍ）构成的光导体显示好的光敏性：表面接受电位，Ｖｍａｘ＞７００Ｖ；残余电位，Ｖｍｉｎ＜５０Ｖ；暗衰速率，ＲＤ＜１０Ｖ／ｓ；光衰放电量，△Ｖｔ＞５０％（１．０ｓ）；半衰时间，Ｔ１２＝０．８７Ｓ；感光灵敏度，Ｓ＝２．３×１０－３（１ｘ．ｓ）－１，较未增感ＰＰＡ光导体有较大的提高。ＭＧ对ＰＰＡ为光谱增感     

高分子金属微球的磁性能研究

在苯乙烯和丙烯酸共聚物「Ｐ（Ｓｔ－ｃｏ－ＡＡ）」，苯乙烯和４－乙烯吡啶共聚物「Ｐ（Ｓｔ－ｃｏ－４ＶＰ）Ｎｉ、Ｐ（Ｓｔ－ｃｏ－４ＶＰ）Ｃｏ金属微球，研究了它们的交流磁化率，磁滞回线，居里温度等磁性能。结果表明制得的了的微球为软磁材料，热重（ＴＧ）分析了则得Ｐ（Ｓｔ－ｃｏ－ＡＡ）Ｎｉ和Ｐ（Ｓｔ－ｃｏ－４ＶＰ）Ｎｉ的居时温度（Ｔｃ）分别为１７５℃和１８０℃，远远低于块状金属的居里温度值。     

聚乙二醇-聚二氧六环酮嵌段共聚物的合成及表征

用辛酸亚锡［Ｓｎ（Ｏｃｔ）２］作催化剂，进行了端羟基聚乙二醇（ＰＥＧ）和１，４ 二氧六环酮（ＤＯＮ）的共聚反应，得到嵌段共聚物ＰＤＯＮ ｂ ＰＥＧ ｂ ＰＤＯＮ．根据１Ｈ ＮＭＲ谱图计算结果表明共聚物组成随两组分投料比而改变．共聚物的ＤＳＣ结果表明嵌段共聚物中ＰＤＯＮ的熔点和结晶度的变化相对较小，而ＰＥＧ的熔点及结晶度均有较大降低．将ＰＥＧ引入可大大提高材料的吸水率．     

选择性接聚乙烯醇枝聚醚氨酯的合成及其血液相容性

合成了α－甲基，ω－（２，３－环氧丙基）－聚乙二醇醚（Ⅱ）．经水解得到悬挂聚乙二醇（ＰＥＧ）枝的丙二醇－２，３（Ⅲ）．用二元醇（Ⅲ）为扩链剂制得了在硬链段上接有ＰＥＧ枝的聚醚氨酯（Ｈ－ＰＥＵ）．以四氢呋喃与少量大分子单体（Ⅱ）进行正离子开环共聚合制得每个链接有约１．３个ＰＥＧ枝的聚丁二醇（Ⅳ），用以合成了在软链段上接有ＰＥＧ枝的聚醚氨酯（Ｓ－ＰＥＵ）．ＥＳＣＡ及抗凝血性研究结果表明，不同位置接枝的ＰＥＵ，其表面都有明显的聚醚链段富集．Ｓ－ＰＥＵ抗凝血复钙时间只比未接枝者增长约２０％，而Ｈ－ＰＥＵ则增约一倍，比Ｓ－ＰＥＵ增约６０％．随ＰＥＧ最增大，复钙时间增长．     

含时间变量的凝胶溶胶分配方程及其应用

在Ａａ－Ｂｂ型综聚反应的凝胶溶胶分配（ＧＳＤ）方程中引入相应的聚合反应动力学方程．模拟计算的溶胶分数（Ｓ）对反应程度（Ｐ_Ｂ，Ｐ_Ｂ＇）的关系曲线与实验结果基本吻合．利用含时间的ＧＳＤ方程，解决了非线型缩聚反应交联网络的模拟计算，给出了交联度随时间的变化曲线，也为凝胶点的计算提供了一种方法．     

高聚物两相体系相行为的流变学研究──Ⅱ．嵌段高聚物微相溶合的研究

本文从流变学角度研究了三嵌段高聚物苯乙烯－丁二烯－苯乙烯（ＳＢＳ）中的微相转变，从相转变温度前后流变行为的变化，确定了相转变温度，其结果与小角Ｘ光散射的结果一致，在此基础上，研究了嵌段高聚物的微相溶合过程，发现相溶合过程可分为四个阶段，在第二，第四阶段，Ｇ’～ｅαｔ，’～ｅβｔ，矿是相溶合时间，α，β随相溶合温度及阶段不同而改变．以Ｄｉｃｋｉｅ模型为基础，考虑到分子运动及剪切条件下的流体力学相互作用，分析了各阶段的流变行为，初步说明了微相溶合过程中，流变行为时间依赖性的本质．     

水煤气变换反应的微观动力学分析——钾影响铜催化剂活性的MonteCarlo模拟研究

运用ＢＯＣ－ＭＰ方法和ＭｏｎｔｅＣａｒｌｏ模拟方法，讨论了在钾存在的情况下，Ｃｕ（１００）上ＷＧＳ反应中各反应物种吸附热性能的变化，以及各表面基元反应步骤动力学参数的变化规律．研究结果表明，当钾处于低覆盖度时（＜０．１０），ＷＧＳ反应的反应速率随表面钾浓度的增大而增大；而当钾表面浓度较高时，反应速率却随表面钾覆盖度的增大而减小．这可能是由于反应的速控步骤随表面钾覆盖度的变化而发生了改变     

聚氨酯改性环氧树脂／聚苯乙烯IPNs的固化动力学：II苯乙烯含量…

用化学滴定、粘度测定等方法，研究了苯乙烯含量对聚醚型聚氨酯改性双酚Ａ型环氧树脂（ＰＵＤＧＥＢＡ／聚苯乙烯（ＰＳｔ）室温同步半－ＩＰＮ’ｓ（简称ＳＩＰＮ’ｓ）体系固化动力学的影响。结果表明，在上述所研究的体系中，苯乙烯含量的变化对凝胶时间有着不可忽略的影响。随苯乙烯含量的增加，凝胶的时间明显延长。随苯乙烯含量的变化，两个组分固化反应反应速度最大值到来的时间可以相对提前或延后，甚至达到刚好同步，对上述     

Theoretical Study of Glycidol Hyperbranching Polymerisation

Bulk hyperbranched anionic polymerisation of glycidol initiated by methoxide anion has been studied at B3PW91/6‐311+G(2d,p)//HF/6‐31G/d′) and MP2/6‐31+G(d′)//MP2/6‐31+G(d′) levels of theory. The Isodensity Polarised Continuum model was applied to take into account the environment effect. The results of molecular modelling are in good agreement with experimental data. According to the calculations glycidol polymerisation is thermodynamically controlled. The attack on the unsubstituted glycidol end is thermodynamically preferred except for the very first polymerisation step. Fast proton exchange reaction takes place during the polymerisation giving rise to the branching reaction. While the linear growth is caused by primary alkoxide attack, the branching reaction occurs by secondary alkoxide attack on the next glycidol molecule. It was found that cyclisation reactions show higher activation energies and are less favourable thermodynamically compared to polymerisation.     

Synthesis of EDTA core dendrimers through a consecutive esterification-CuAAC process

A novel class of thermostable G0 and G1-dendrimers was synthesized from the coupling of both propargyl and azido esters derived from EDTA through copper catalyzed azide-alkyne cycloaddition. The branching and size in these compounds were controlled by a simple azide-alkyne group position change in the CuAAC reaction in conjunction with the use of 1,3-diazido-propan-2-ol as a polyfunctional compound.     

CH自由基和NO~2反应研究: II.反应的动力学计算

采用MP2(FULL)/6-31G(d)方法从动力学计算上探讨了CH自由基与NO~2反应的可能途径,找到了反应物,中间体及产物之间的能量通道和过渡态,报道了它们的构型、电子态及能量。并通过频率分析和IRC方法对所有的过渡态进行了验证。在此基础上求出了各步反应的活化能。在以前热力学研究的基础上,对于可能的反应通道进一步作了动力学分析,找到了反应主产物通道的分支比,与实验得到的分支比基本吻合。     

Intrinsic reaction coordinate calculations for reaction paths possessing branching points

A 3-21+G energy surface corresponding to the proton transfer reaction in the hydroperoxyl anion solvated by one water molecule presents interesting topological features. In particular the intrinsic reaction coordinate that begins at the transition state does not lead to a minimum but to a saddle point of second order passing through two branching points. A new strategy to obtain the true reaction path in these cases is proposed.     

Rate Coeffcients and Branching Ratio for Multi-Channel Hydrogen Abstractions from CH3OH by F

The hydrogen abstraction reaction F+CH₃OH has two possible reaction pathways: HF+CH₃O and HF+CH₂OH. Despite the absence of intrinsic barriers for both channels, the former has a branching ratio comparable to the latter, which is far from the statistical limit of 0.25 (one out of four available H atoms). Furthermore, the measured branching ratio of the two abstraction channels spans a large range and is not quantitatively reproduced by previous theoretical predictions based on the transition-state theory with the stationary point information calculated at the levels of M?ller-Plesset perturbation theory and G2. This work reports a theoretical investigation on the kinetics and the associated branching ratio of the two competing channels of the title reaction using a quasi-classical trajectory approach on an accurate full-dimensional potential energy surface (PES) fitted by the permutation invariant polynomial-neural network approach to ca. 1.21x10⁵ points calculated at the explicitly correlated (F12a) version of coupled cluster singles doubles and perturbative triples (CCSD(T)) level with the aug-cc-pVDZ basis set. The calculated room temperature rate coeffcient and branching ratio of the HF+CH₃O channel are in good agreement with the available experimental data. Furthermore, our theory predicts that rate coeffcients have a slightly negative temperature dependence, consistent with barrierless nature of the reaction.     

Short branching in poly(vinyl alcohol). III. Some properties of model polymers of short-branched poly(vinyl alcohol)

Melting point, the iodine color reaction, and foam fractionation were studied on model poly(vinyl alcohol) (PVA) having short branches of one or two monomer units in length. An increase in the amount of short branching units caused a marked decrease in color intensity of the PVA–iodine reaction and in the melting point. These tendencies were more remarkable when the short branching was two monomer units in length than when it was one monomer unit. It was also found that foam fractionation of an aqueous PVA solution produced PVA fractions with different degree of short branching, the degree increasing with increase in the fraction number. The color intensity of the PVA–iodine reaction has been confirmed to decrease with increase in the fraction number, but this result cannot be explained solely in terms of the short branching. It is concluded that the phenomenon of foam fractionation of PVA and the iodine color reaction of the fraction appear to be governed by many factors such as molecular weight, stereoregularity, and short branching.     

Photodissociation of azulene at 193 nm: ab initio and RRKM study

The ab initio/Rice-Ramsperger-Kassel-Marcus (RRKM) approach has been applied to investigate the photodissociation mechanism of azulene at 6.4 eV (the laser wavelength of 193 nm) upon absorption of one UV photon followed by internal conversion into the ground electronic state. Reaction pathways leading to various decomposition products have been mapped out at the G3(MP2,CC)//B3LYP level and then the RRKM and microcanonical variational transition state theories have been applied to compute rate constants for individual reaction steps. Relative product yields (branching ratios) for the dissociation products have been calculated using the steady-state approach. The results show that photoexcited azulene can readily isomerize to naphthalene and the major dissociation channel is elimination of an H-atom from naphthalene. The branching ratio of this channel decreases with an increase of the photon energy. Acetylene elimination is the second probable reaction channel and its branching ratio rises as the photon energy increases. The main C8H6 fragments at 193 nm are phenylacetylene and pentalene and the yield of the latter grows fast with the increasing excitation energy.     

Synthesis of Branched Polyglucans by the Tandem Action of Potato Phosphorylase and Deinococcus geothermalis Glycogen Branching Enzyme

An enzymatic tandem reaction is described in which the enzymes phosphorylase and Deinococcus geothermalis glycogen branching enzyme (Dg GBE) catalyze the synthesis of branched polyglucans from glucose‐1‐phosphate (G‐1‐P). Phosphorylase consumes G‐1‐P and polymerizes linear amylose while Dg GBE introduces branching points on the α‐(1 → 6) positions by reshuffling short oligosaccharides. The resulting branched polyglucans have an unusually high degree of branching of 11%.

     

高密度聚乙烯的熔融支化及其对性能的影响木

在引发剂过氧化二异丙苯、二官能度单体新戊二醇二丙烯酸酯和自由基活性调控剂二甲基二硫代氨基甲酸锌的存在下,使高密度聚乙烯进行熔融支化反应.研究表明,转矩曲线上的反应峰顶对应最佳反应时间,由此获得了凝胶量低的长链支化高密度聚乙烯.熔融支化反应使聚乙烯的分子量分布变宽,其支化程度随单体含量的增加而增大,呈现出更加明显的剪切变稀行为;长链支化结构的引入使改性聚乙烯的结晶度降低,长支链的成核作用使起始结晶温度增加,球晶尺寸明显减小.改性聚乙烯的支化程度和大分子拓扑结构的变化对耐环境应力开裂性能的影响显著,当单体含量超过0.6 phr时,长链支化分子形态从类似不对称星形转变为梳形,使得高密度聚乙烯的耐环境应力开裂时间产生突变,达1000 h以上,同时强度、模量和冲击韧性均得到明显提高.