具有共轭主链聚合物单晶的低温电导测定

用自行组装的低温电导测定装置对77～373K温度范围内双(对甲苯磺酸)-2,4-己二炔-1,6-二醇酯(TS)及其聚合物PTS单晶体的暗电导进行了测定。在c方向上相应于它们低温相转变的温度,TS和PTS的电导均出现异常,此时TS的相变温度是163K和208K。     

TS单晶体及其聚合物PTS的介电和动态力学行为

<正> 聚丁二炔类宏观单晶体以其极大的尺寸,完整性和立体规整的共轭主链,为我们提供了一个准一维体系模型化合物。它们的电性能,非线性光学性能及形成聚合LB膜的能力等具有潜在的应用前景,近年来研究工作非常活跃。丁二炔类化合物中最能培养咸大晶体,从而研究得最多的是双(对甲苯磺酸)-2,4-己二炔-1,6-二醇酯(TS)及其聚合物PTS。我们先后测量过它们的热电势率、电导、膨胀系数、介电性能、光声效     

二氯二茂钛引发二苯乙炔聚合的研究

在高温下 ,二氯二茂钛受光照引发二苯乙炔聚合 ,得到结晶度为 95 %的聚二苯乙炔 .经红外、质谱、热分析、X光衍射、元素分析等方法 ,确定其结构为顺顺式螺旋刚性棒状结构 ,形成假六方晶系堆积 ,螺旋柱直径即螺旋轴间距为 1 46nm ,其特征红外吸收峰位于 1179cm-1和 115 6cm-1.在聚合引发阶段中止反应 ,分离出聚合中间体六苯基苯 .根据不同温度时聚合转化率与时间的关系曲线 ,测得聚合活化能为 2 6× 10 5J/mol.热分析表明 ,结晶聚二苯乙炔在 493K至 5 73K比较稳定 ;在 713K的吸热峰显示出破坏晶格的能量 .根据聚合反应诱导期长、中间体和聚合物的结构以及阻聚反应 ,推断聚合过程中二氯二茂钛受光照产生二氯化钛 ,催化二苯乙炔进行均相定向聚合 .结晶聚二苯乙炔电导率小于 10 -12 (Ωcm) -1.     

激光测微法研究双(对甲苯磺酸)-2,4-已二炔-1,6-二醇酯的固态热聚合

用激光测微法跟踪了双(对甲苯磺酸)-2,4-己二炔-1,6-二醇酯(TS)固态晶相热聚合时宏观尺寸的变化,由此推算TS聚合时晶胞参数的变化。结果表明,在形成聚合物PTS大分子链的c轴方向上一直收缩,而在横向a、b方向上则是先膨胀后收缩。     

高压下DPP-11超分子结构中的π-π相互作用

通过金刚石对顶砧(DAC)高压装置产生高压, 利用原位高压同步辐射能量色散X射线衍射(EDXD)和同步辐射远红外光谱研究了压力对DPP-11[2,5-二-(11-十一醇基)-3,6-二-(2-噻吩基)-1,4-二酮吡咯并[3,4-c]吡咯]固体及其在水溶液中胶束体系的影响. 实验结果表明, 在准静水压条件下, DPP-11固体没有发生相变, 但随着压力的增加, 分子间的π-π相互作用明显增强. 在DPP-11胶束中发现了DPP-11固体中新的远红外吸收峰, 此峰随着压力的增加而蓝移, 这是由于胶束中π共轭染料基团的π-π相互作用增强所致.     

二茂铁基β-二酮及其Cu(Ⅱ)、Ni(Ⅱ)配合物的燃速催化性质

合成了含有苯基的二茂铁β-二酮,并对其结构进行了表征.在核磁共振氢谱中,苯环上含有拉电子的硝基时,β-二酮烯醇式含量几乎是100%,而含有给电子的甲氧基时,其烯醇异构体含量下降到84%.当将其与Cu(II)或Ni(II)配位后,在紫外吸收光谱中,300 nm以下归属于Fe(d)-π*和芳基π-π*的跃迁向长波方向移动5~17 nm.热重-差示扫描量热法(TG-DSC)实验表明,添加二茂铁基β-二酮或它们的Cu(II)或Ni(II)配合物于高氯酸铵(AP)中,不仅在一定程度上抑制了AP高温热降解阶段的升华,而且可使AP的热降解温度提前,以Cu(II)配合物提前得更为显著,含有甲氧基的Cu(II)配合物可使AP的热降解温度提前87℃.因此相对于二茂铁β-二酮配体及Ni(II)配合物,Cu(II)配合物是更好的燃速催化剂.     

癸二醇和十二烷二醇及其混合物的液固相变研究

使用差示扫描量热法（DSC）和红外光谱法（IR）对1，10-癸二醇（1，10-C10H22O2，A）与1，12-十二烷二醇（1，12-C12H26O2，B）及其二元混合物系统液固相变进行研究。测定了该二元混合系统的相变温度、相变焓和液固平衡相图。该二元系统存在低共熔混合物，其组成为xB=0．333，低共熔温度为328K。该二元混合系统的IR图谱显示存在氢键缔合现象，长链烷烃中的亚甲基在晶格中是有序规则排列的。该系统具有较低的相变温度和较高的相变焓，是一种潜在的低温储能材料。     

细胞色素C在4,5-二氮芴-9-酮修饰玻碳电极上的直接电化学研究

采用循环伏安法探讨了细胞色素C(Cyt C)在4, 5-二氮芴-9-酮(dafo)修饰玻碳电极表面的电化学行为.结果表明,Cyt C在dafo修饰电极上呈现一对峰形较好且准可逆的氧化还原峰,其式电位(E0′)为13 mV,峰电流与扫描速度呈线性关系,该电极过程是表面控制过程,电化学反应效率常数(ks)为0.89/s.固定在dafo上的Cyt C能促进H2O2的催化还原,响应快速而灵敏(<10 s),峰电流与H2O2浓度在5.0×10-6～3.0×10-4 mol/L范围内呈线性关系;检出限2.5×10-6 mol/L;米氏常数为1.07 mmol/L,显示出较好的亲和力.     

席夫碱的合成及热色性研究Ⅲ——二取代苯甲醛-二-对-氨基苯甲烷类席夫碱

本文合成了二取代苯甲醛-二-对-二氨基苯基甲烧类席夫碱类的7个化合物,并应用物理方法进行了表征.通过加热显微观察,这些化合物都具热色性,而其中4种具有可逆热色性.此外应用差热分析阐述了这类席夫碱的吸热峰的ΔH(ΔS)与其结构的关系.     

4,6-二甲基-N-苯基-2-嘧啶胺的低温热容和热力学性质

通过小样品精密自动绝热量热计测定了合成并提纯的 4,6 二甲基 N 苯基 2 嘧啶胺 (嘧霉胺 )在 78～ 3 91K温区的摩尔热容 .量热实验发现 ,该化合物在 3 63～ 3 72K温区 ,有一固 -液熔化相变过程 ,经三次重复测量 ,得其熔化温度、摩尔熔化焓及摩尔熔化熵分别为 :( 3 70 78± 0 0 8)K ,( 2 1 2 3 3± 0 0 13 )kJ·mol-1 和 ( 5 7 2 7± 0 15 )J·mol-1 ·K-1 .通过分步熔化法得到该物质绝对纯样品的熔点为 3 71 0 3 1K .用差示扫描量热 (DSC)技术对该物质的固 -液熔化过程作了进一步研究 ,结果与绝热量热法一致     

钛酸铅与偏氟乙烯-三氟乙烯共聚物形成的铁电复合物相变过程的热释电研究

研究了偏氟乙烯-三氟乙烯共聚物与钛酸铅形成的铁电复合物PT/P[VDF(70)-TrFE(30)]的热释电流行为。P[VDF(70)-TrFE(30)]室温下存在两个铁电相,即较无序的铁电相和较有序的铁电相,升温经过各自的相转变点后转变成较有序的顺电相和较无序的顺电相。热释电流谱上出现在95℃和108℃的两个电流峰,分别由两个铁电相的结构陷阱以及部分取向的偶极所贡献。采用Tc以上温度极化并冷却到不同温度的方法可明确鉴别出该试样两个顺电相降温转变过程,转变点分别为62℃和50℃。实验证实陷阱仅存在于铁电相而不存在于顺电相中。钛酸铅的引入虽不导致新电流峰出现,但可使共聚物的Tc降低、电流加大。热释电流方法可非常灵敏地跟踪铁电共聚物的相变过程。     

Raman Investigation of the Low Temperature Phase Transitions in Monoclinic TlReO4

The Raman spectrum of monoclinic TlReO₄ is presented together with a factor group analysis and assignment of the bands. The phase transitions of monoclinic TlReO₄ is investigated below room temperature, and two phase transitions were identified between room temperature and 90 K. The room temperature monoclinic phase was converted to the orthorhombic phase at 170 K upon cooling, and to the tetragonal phase at 150 K. Upon heating back to room temperature the tetragonal phase persisted until the orthorhombic phase could be identified at 210 K and 220 K. From 230 K to room temperature the monoclinic phase could again be observed.     

四氯合铜酸二烷基铵相变的热分析和红外光谱

用DSC和TG研究了(n-C_nH_(2n+1)NH_3)_2CuCl_4(n=7-12)(记为C_nM)配合物的热稳定性和固-固相变。由红外光谱讨论了C_9Cu三个相的性质。发现C_nM的热稳定性呈奇偶效应; 主相变峰温随链长增长而升高; 相变总ΔH和ΔS也随链增长而加大; 当n≤9时, 高温相为部分无序相; 而n≤10时, 高温相为构象无序相。C_9Cu的主相变主要源自链间堆积结构变化。而在307.7 K的相变主要与烃链有序-无序变化有关。     

Sn-containing liquid crystalline side group homopolymers with two glass transitions

Three homologous tin-containing homopolymers with a terminal CN-dipole in the side group have been synthesized and characterized by dynamical calorimetry, polarization microscopy, X-ray and dielectric methods. AFM was used to evaluate the texture at room temperature. Four different phase transitions were detected by DSC. The high temperature phases were identified by polarization microscopy as SmA and SmC. AFM-measurements show focal-conic domains at room temperature and confirm so the smectic nature of all phases. X-ray measurements on nonoriented samples give hints to a phase segregation on nanometer scale. Dielectric investigation and temperature-modulated DSC (TMDSC) confirm clearly phase separation by appearance of two glass transitions related to the liquid order of the main chains and the liquid crystalline of the side groups.     

Influence of La3+ on the Phase Behavior and the Pluidity of Phospholipid Bilayers

The influence of La³⁺ on the phase behavior and the fluidity of the negatively charged phospholipid dipalmitoylphosphatidylglycerol(DPPG) bilayers was studied by differential scanning calorimetry (DSC) and FT-Raman spectroscopy. La³⁺, induced a phase separation of DPPG bilayers, and formed three peaks. La³⁺ increased the phase transition temperature of the new peaks, broadened the half width of the DSC signal, and stabilized a gel phase relative to a crystalline phase of DPPG bilayers. La³⁺ was shown to increase interchain order and intermolecular ordering of the lipid lattice, and decreased the fluidity of DPPG bilayers.     

Thermodynamics of activated phase transitions of 8CB: DSC and MC calorimetry

The present paper reports the heating rate effect on the phase transitions of a pure liquid crystal octylcyanobiphenyl (8CB) with use of Differential Scanning Calorimetry (DSC) and Modulation Calorimetry (MC) techniques. The DSC runs were taken at various temperature ramp rates from 20 to 0.5 K/min for heating and cooling scans. Well-defined endothermic/exothermic peaks were found at the melting/crystallization, smectic-A to nematic (SmA-N), and nematic to isotropic (N-I) transitions on heating/cooling scans, respectively. All transitions shift in temperature significantly with different ramp rates. The temperature shift of C(p) peaks between heating and cooling scans indicates the order of the transitions. In addition, all transitions follow an Arrhenius behavior. The activation energy of a transition increases as the total energy involved in the transition decreases. The respective enthalpy and entropy change of each transition provides information on the Gibbs free energy. The significance of the results is discussed in terms of the order of transitions. A comparative analysis of MC and DSC techniques highlights the significance of the two techniques. MC is a practicable tool for observing the phase dynamics whereas DSC is a good tool for studying the rate kinematics of the transitions.     

A_a型Patchy胶体粒子的相态结构

根据热力学微扰理论研究了Aa型Patchy胶体的相态结构,考察了Patch之间的缔合强度及Patch数目对体系相态结构的调控机制.利用相平衡原理给出了Patchy胶体的流体、玻璃态固体和面心立方晶体之间转变及溶胶-凝胶转变的相图,讨论了玻璃态和晶态固相的成核机制、临界现象和相变问题.研究结果表明,Patchy胶体粒子之间的缔合作用和Patch数目可以显著地调控体系的三相点、临界温度和临界密度等特征.在高温条件下,Patchy胶体以一次成核方式结晶;而在低温条件下则以两步成核方式逐步成核结晶,中间经过非晶态的玻璃态固相作为过渡.说明Patchy粒子之间的缔合作用对其相态结构具有决定性影响,因而成为调控体系聚集态结构的重要因素.     

糖类对水合DHPE相变的影响

人们发现,许多据说是处在脱水生存（anhydrobiosis）状态下的干生物在无水情况下可以坚持存活数十年之久．在这些干生物体中经常包含大量的糖类和糖醇,而后两者似乎和这些生物在干燥状态存活有关[1]．此外,已经证明某些糖类能够保护磷脂膜[2]和细胞膜[3]不受冷冻和脱水造成的伤害．对耐干旱、耐霜冻生物的企求,对冷冻保存细胞、组织或器官时所用的冷冻保护剂（cryoprotectant）的求索,唤起了人们对糖类和磷脂膜相互作用研究的兴趣．在已经进行过的研究中,极大部分是使用磷脂酰胆碱（PC）或PC和磷脂酰丝氨酸的二元混合物作为形成双分…     

The relationship between phase transition and luminescence in simple hydrocarbons

A satisfactory correlation between the temperature of radiothermoluminescence (RTL) peaks and phase transition points has been found in simple hydrocarbons. RTL peaks due to a glass transition phenomenon are observed clearly in ethane, propane and other compounds. These compounds were deposited rapidly onto a cooled cooper surface from the vapour (the vapour condensation method). A method for studying phase transitions in several substances by means of RTL is proposed.     

Raman investigation of the order-disorder phase transitions in the 2[N(C3H7)4]SbCl4 compound

The Raman spectra of bis (tetrapropylammonium tetrachloroantimonate (III)) 2[(C₃H₇)₄N]SbCl₄ compound single crystals were studied in the wavenumber range from 3500 to 50 cm⁻¹ for temperatures between 300 and 415 K. Two phase transitions occurring at 343 (T_tr1) and 363 K (T_tr2) were observed and characterized. The strong evolutions of the Raman shift, half-widths and intensity of many lines associated with the organic cations were observed with discontinuities in the vicinity of the two phase transitions. The most important changes were noticed for the band at 307 cm⁻¹ (at room temperature) assignable to the torsion of CH₃ groups of the cations. The spectral characteristics of this band was analyzed and consistently described in the framework of an order–disorder model for the two phase transitions. They allowed us to obtain information relative to the activation energy, the correlation length, and the critical exponent of the mechanism. The decrease of the estimated activation energies for the band 307 cm⁻¹ with the increase in temperature has been interpreted in terms of a change in the reorientation motion of cations. The temperature dependence of the reduced peak intensity allowed for the determination of the critical exponents and evolution of the correlation length on approaching the transition.