化学反应的内禀反应坐标法V. 顺-, 反-氟代乙烯基负离子异构化反应的反应路径解析

本文对顺-, 反-氟代乙烯基负离子异构化反应的反应途径进行了微观动力学解析。在RHF/4-31G水平上优化求得了反应物、过渡态及产物的平衡几何和总能量, 得到了活化能、反应热、A因子及活化熵等一些物理量, 从反应物到过渡态的振动相关表明: 正则振动模式是各自独立的; 键角H(1)-C-C的伸缩振动模式直接与内禀进动(IRC)相连结。这为模式选择化学反应的研究提供了信息。     

酞菁钴吡啶轴向配合物的合成及表征

从4-硝基邻苯二腈出发，首先合成了酞菁钴的衍生物——对称的四取代烷基苯氧基酞菁钴，并以此为基础，采用溶剂热的方法合成了与吡啶形成的无取代轴向配合物，对相关化合物进行了红外、紫外、质谱的表征．初步尝试了由溶剂热的方法制备金属酞菁轴向配合物．     

Synthesis and phase behavior of polyurethanes end-capped with fluorinated phosphatidylcholine head groups

A series of fluorinated phosphatidylcholine polyurethane macromolecular additives were synthesized by solution polymerization using methylenebis(phylene isocyanates)(MDI) and 1,4-butanediol(BDO) as hard segments,a new phoshporycholine,2-(2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9-hexadecafluoro-10-(2-hydroxyethoxy)decyloxy) ethyl phosphorycholine (HDFOPC) as end-capper,and four polydiols,poly(tetramethylene glycol)s(PTMG),polydimethylsiloxane(PDMS), poly(1,6-hexyl-1,5-pentylcarbonate)(PHPC) and poly(propylene glycol)(PPG) as soft segments,respectively.The chemical structures of the synthesized polyurethanes were characterized by ~1H-NMR and FTIR.DSC and DMA were employed to study the phase behavior of these novel polyurethanes due to their great influences on the surface properties,and hence their interactions with bio-systems.The results showed that phase separation of the fluorinated phosphatidylcholine end-capped polyurethanes was increased in comparison with that of normal polyurethanes.The effect of fluorinated phosphatidylcholine end-capped groups on the phase behavior was further demonstrated by analyzing the degree of hydrogen-bonding between hard and soft segments.     

The variable role of clay on the crystallization behavior of DMDBS-nucleated polypropylene

The effect of clay on the nucleating behavior of 1,3:2,4-bis(3,4-dimethylbenzylidene) sorbitol(DMDBS) in cryatallization of isotactic polypropylene(iPP) was investigated by means of differential scanning calorimetry(DSC), dynamic rheology and polarized light microscopy(PLM).It is interesting to note that the incorporation of layered clay nanoparticles into DMDBS-nucleated iPP may induce a synergetic nucleation effect while the DMDBS content is below 0.1 wt%,otherwise it restricts the crystallization rate prominently as the DMDBS content increases up to 0.3 wt%,which has exceeded the content threshold to yield a nucleating agent(NA) network.As shown by dynamic rheological investigations, the clay nanoparticles demonstrate an obstructive effect of disturbing the consistency of DMDBS fibrils network.Moreover, to further demonstrate the importance of NA network formation in the crystallization of iPP,we used another NA named HPN-20e,which can not form network structure at all over the concentration studied,for comparison.In this case,the nucleated-crystallization rate is independent on the addition of clay nanoparticles,as the nucleating mechanism is an individual nuclei manner without NA network forming.     

Effects of matrix molecular weight on structure and reinforcement of high density polyethylene/mica composites

Three types of high-density polyethylene(HDPE)with different molecular weights(high,medium and low)were adopted to evaluate the influence of matrix molecular weight on the structure-property relation of injection-molded HDPE/mica composites through a combination of SEM,2d-WAXS,DSC,DMA and tensile testing.Various structural factors including orientation,filler dispersion,interfacial interaction between HDPE and mica,etc.,which can impact the macroscopic mechanics,were compared in detail among the three HDPE/mica composites.The transcrystallization of HDPE on the mica surface was observed and it exhibited strong matrix molecular weight dependence.Obvious transcrystalline structure was found in the composite with low molecular weight HDPE,whereas it was hard to be detected in the composites with increased HDPE molecular weight.The best reinforcement effect in the composite with low molecular weight HDPE can be understood as mainly due to substantially improved interfacial adhesion between matrix and mica filler,which arises from the transcrystallization mechanism.     

分级加载条件下紫色泥岩三轴蠕变特性研究

流变性质是岩石材料的重要力学特性,以紫色泥岩为例,在分级加载条件下研究了其三轴蠕变特性。采用自行研制的重力杠杆式岩石蠕变实验机,并配备三轴压力室,对紫色泥岩实施分级加载三轴蠕变实验。实验结果表明,紫色泥岩在相同轴压条件下,围压越大,瞬时弹性变形和蠕变变形越小;在相同围压条件下,轴压越大,二者变形越大。紫色泥岩的蠕变速率具有相同的变化趋势,且在相同轴压条件下,围压越大,稳定蠕变阶段的蠕变速率越不明显。另外,应力与瞬时应变线性拟合结果表明,瞬时轴向应变与轴向荷载近似成比例增长。通过分析紫色泥岩蠕变曲线变化趋势,认为采用H/M模型进行模拟较为合理。并且采用MATLAB软件非线性回归分析进行模型参数拟合,最后得到实验曲线与理论曲线的最大误差在2e-5左右。证明采用的H/M模型能较好地描述紫色泥岩的蠕变特性。     

PREPARATION AND CHARACTERIZATION OF SOY PROTEIN ISOLATE(SPI)/MONTMORILLONITE(MMT) BIONANOCOMPOSITES

 The bionanocomposites of soy protein isolate (SPI)/montmorillonite (MMT) have been prepared successfully via simple melt mixing, in which MMT was used as nanofiller and glycerol was used as plasticizer. Their structures and properties were characterized with X-ray diffraction (XRD), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), thermogravimetric analysis and tensile testing. XRD、TEM and SEM results indicated that the MMT layers could be easily intercalated by the SPI matrix even by simple melt processing. The exfoliated MMT layers were randomly dispersed in the protein matrix as MMT content was low (less than 5 wt%), an incomplete exfoliation was evident from SEM results, and some primary particles were observed as the MMT content was high (from 5 wt% to 9 wt%). A significant improvement of the mechanical strength and thermal stability of SPI/MMT nanocomposites has been achieved. Our work suggests that simple melt processing is an efficient way to prepare SPI/MMT nanocomposites with exfoliated structure.     

负载型磺酸化席夫碱二-邻苯甲醛乙二胺(Salen)-Mn(Ⅲ)配合物催化不对称环氧化反应

设计了负载型催化剂/离子液体体系：磺酸化席夫碱二-邻苯甲醛乙二胺(Salen)-Mn(Ⅲ)配合物中5, 5′-磺酸根通过氢键作用分别负载于硅胶和硅藻土,再分散于亲水性离子液体1-正丁基-3-甲基咪唑四氟硼酸盐(BMImBF₄)或憎水性离子液体1-正丁基-3-甲基咪唑六氟磷酸盐(BMImPF₆)中。研究了此催化体系对苯乙烯和α-甲基苯乙烯的不对称环氧化反应,结果表明此体系减少了催化剂的流失,催化体系可循环五次;扩大了手性诱导能力,对映体过量值(ee)可达100%;     

我国能源化学学科发展的初步探析

能源化学是在世界能源需求日益突出的背景下处于发展初步阶段的新兴交叉学科,主要利用化学的理论和方法来研究能量获取、储存及转换过程的规律,探索能源新技术的实现途径.作为能源学科中最主要的二级学科之一,能源化学是在融合物理化学、材料化学和化学工程等学科知识的基础上而提升形成,兼具理学、工学相融合大格局的鲜明特色,是指导能源高效利用和新能源开发的关键学科之一.能源科学很可能跟随材料科学和环境科学形成壮大的足迹,成为被学术界、工业界和社会所广泛认可的新兴一级学科,进而被基本学科指标数据库(Essential Science Indicators,ESI)所收录,能源化学则有望最早搭建起全面系统的知识框架体系,成为能源科学二级学科分支中的前行者和引航员.本文对能源化学学科的内涵及分类、战略地位、规律及特点等进行了梳理和分析,在明确学科发展目标与学科任务的基础上,提出了对我国能源化学学科发展的初步建议.目前需要把握国际尚未建立能源化学学科特别是本科-研究生教育体系的关键时机,借助高校体制机制改革的东风,集中全国优势力量,全面细致地做好顶层设计和学科规划,编写出国际首套本科生教材,加快在部分基础好的高校开展试点工作,力争在国际上引领能源新学科的建立、发展与应用.     

剪切作用下PA1010/PP共混物的形态与性能研究

通过动态保压注射成型方法制备了聚酰胺1010/聚丙烯(PA1010/PP)共混物,并研究了形态与性能的关系.力学性能测试结果表明在熔体冷却过程中施加剪切可以大大提高共混物的拉伸强度、拉伸模量和缺口冲击强度,当PP的质量分数为20%时,共混物的缺口冲击强度达到21.3kJ/m2,是静态样的3倍多,拉伸强度达到50.9MPa,是静态样的1.5倍.扫描电镜(SEM)结果表明在动态保压样的横断面可以观察到剪切诱导的形态,中间是芯层,围绕着芯层的是剪切层,最外面是皮层,相区尺寸显著减小、分散相分散更趋均匀,特别是PP的质量分数为20%时,相区尺寸从原来的约3.9μm降低到约1.4μm.动态保压样机械性能的提高归因于剪切作用下独特相形态的形成,分子链沿流动方向的取向是拉伸强度提高的主要原因,而剪切使分散相颗粒变小和剪切层中分子链的取向是冲击强度提高的主要原因.