聚芳醚酮单体分子与分子极化的13C NMR研究

为弄清聚芳醚酮单体在硫酸中变色(红)现象,通过¹³C NMR研究了它们在CDCl₃、CDCl₃+DMSO-d₆和H₂SO₄的¹³C谱化学位移及氟端基偶合情况.研究表明:这些单体溶于硫酸时,羰基碳弛豫时间缩短化学位移增加,而与羰基相连的季碳弛豫时间减小化学位移也减少.据此,首次提出硫酸使这些单体极化的机理为正极性磺酸基使羰基发生电子离城,变温¹³C谱对此进行了验证.     

聚芳醚酮链扩展单体及单分散齐聚物的分子结构研究

为了全面表征聚芳醚酮齐聚物及高聚物分子结构,本文合成了系列链扩展单体及单分散齐聚物,以¹³C NMR对其在DMSO-d₆(或DMSO-d₆+CDCl₃),及H₂SO₄-d₂(或H₂SO₄)中进行对比研究,表明:它们溶于H₂SO₄时,分子结构发生明显极化.量子化学计算及动态¹³C NMR研究表明,极化是H₂SO₄的正极性磺酸基诱导分子链的氧原子电荷进而诱导芳环电子离域产生的,而非磺化所致.说明极化有普遍意义并提出标题化合物的极化方式,其实际意义明确.     

含萘聚芳醚酮共聚物热处理后产生自由基的ESR谱

萘环摩尔含量20%的聚芳醚酮（PANEK）无规共聚物在340 ℃空气条件下发生交联反应，经过不同时间的热处理后，在室温检测热处理后产生的自由基ESR谱. 它们都有一条较强的单峰，随着热处理时间的增长，自由基ESR谱的幅度增强，将微波功率加大到200 mW, 谱线发生明显的变化，出现两条重叠在一起的谱线，说明含萘环聚芳醚酮在热处理过程中产生了两种不同的自由基. 文中模拟、讨论了热处理过程中产生的两种自由基的归属，一种是RO·自由基，另一种是萘自由基，它们都参与交联反应，RO·自由基起主要作用.     

含萘环聚芳醚酮类聚合物的分子设计与性质研究

聚芳醚酮类聚合物由于具有优良的韧性、刚性、耐热等级高、电性能、耐辐射、耐疲劳、耐冲击、抗蠕变、耐磨、耐热水性好、阻燃性好等特点,在热塑性聚合物领域占有极其重要的位置. 其在航空、航天、核能、信息、通讯、电子电信、石油化工、机械制造、交通运输等高技术领域得到了成功的应用,使许多行业的传统产品实现了更新换代. 但是,随着世界新科技革命的蓬勃发展,对高性能结构材料提出了日益广泛而迫切的需求. 为进一步提高聚芳醚酮类聚合物的性能,满足某些特殊情况下的使用要求（例如高温、高辐照强度）,可考虑对它们进行交联. 使之可用热塑性材料的加工方法加工,然后通过热处理使其交联,成为热固性材料. 这就要求在聚合物链上引入可交联基团. 常用的脂肪族交联基团的引入,会导致聚芳醚酮耐热性降低,而只能寻找芳香族可交联集团的聚合物材料. 本论文的目的是从分子结构设计的角度出发,从合成新型单体入手,采用芳香族亲核取代路线,将萘环引入聚合物主链,合成出一系列的新型含萘环聚芳醚酮类聚合物,并在不同条件下对它们进行了热处理. 主要利用电子自旋共振（ESR）这一手段对热处理前后的聚合物进行了表征,研究了聚合物的热交联行为,讨论了萘环的化学环境、键连位置及热处理条件对交联反应的影响,建议了交联机理.  我们首先通过1,5-萘二酚(1, 5-DHN)、对苯二酚(HQ)和4,4′-二氟二苯酮（DFB）合成了新型高分子量的含1,5-萘二醚型聚醚醚酮无规共聚物（1, 5-PENEK）,发现随着萘环含量的增加, 聚合物的玻璃化转变温度升高,熔点和结晶能力逐步下降直至消失,力学性能略有下降但基本保持了聚芳醚酮的优良性能. 这些性质的改变是由于萘环的引入在增加了聚合物的刚性同时也降低了聚合物的有序排列能力所致. 通过DSC、WAXR检测发现,1,5-萘二醚型聚醚醚酮共聚物（1, 5-PENEK）在320 ℃以上空气中处理时发生交联反应. 随着萘环含量的增加及处理温度的提高,聚合物的玻璃化转变温度增高速度加快,结晶性能迅速下降. 当处理前后的样品用ESR定量检测时,发现只存在一个单峰,并且其幅度随着热处理时间的增加而增强. 增加微波功率时发现在谱峰的两侧有很弱的突起,采用微波功率饱和特性方法证实样品中存在两种性质不同的R₁和R₂自由基. 在不同气氛下处理该样品, 从它们ESR谱的特征推测：R₁可能是RO·自由基,采用改变ESR的检测温度的方法进一步确认热处理后的聚合物中R₁自由基是RO·自由基,并且经计算证明RO·自由基是与分子链中萘环相关联的. 我们又通过模拟的方法证实R₂自由基是萘环自由基. 通过作RO·自由基、萘环自由基的自旋浓度随热处理时间变化曲线发现两种自由基都参与了交联反应,只是RO·自由基的浓度明显高于萘环自由基,在交联反应中起主导作用. 两种自由基浓度随热处理时间的变化趋势相同,即在热处理前期自由基浓度随时间增长很快,中期则变化不大,而后呈线性增长. 可以认为,热处理前期,主要是自由基的激发过程,而中期生成的自由基大多以双基终止的方式被消耗掉,对浓度增长没有明显贡献. 玻璃化转变温度与此相反的变化趋势支持这一结论. 恒温热失重实验表明,1, 5-PENEK在340 ℃热处理时出现明显的分解,说明1, 5-PENEK在340 ℃发生的热交联反应是裂解交联反应. 通过以上测试结果,得到了含1,5-萘二醚型聚醚醚酮共聚物（1, 5-PENEK）在340 ℃热交联的反应机理.  第二部分,我们从1,4-萘二甲酸出发,经过酰氯化反应及付氏酰基化反应,合成了新型单体1,4-二（4-氟苯羰基）萘(1, 4-BFN). 并且利用所得到的单体和4,4′-二氟二苯酮（DFB）与对苯二酚（HQ）通过亲核取代反应合成了含1,4-萘环的聚醚醚酮酮共聚物（1, 4-PEEKNK）. 测试结果表明, 随着萘环含量的增加,1, 4-PEEKNK的玻璃化转变温度升高、 溶解性变好、熔点下降直至消失,1,4-PEEKNK均聚物的力学性能与PEEK相近. 经260 ℃以上热处理的1, 4-PEEKNK均聚物的热分析实验结果表明,随着处理时间或处理温度的增加, 玻璃化转变温度升高. 从而推断在空气中热处理时聚合物发生了交联反应. 结合FT－IR、NMR等提出,交联反应是发生在萘环上的交联反应. 我们同样采用了ESR技术对1, 4-PEEKNK聚合物的交联反应类型进行了研究. 发现自由基的浓度随着处理时间的增加同样经历了3个阶段,由此我们判断1,4-PEEKNK聚合物发生的交联反应为自由基交联反应. 在不同热处理温度下1, 4-PEEKNK聚合物处理8 h的自由基自旋浓度表明在260 ℃和300 ℃热处理时自由基浓度增加的很少,与未处理样品的浓度几乎一致,认为这是由于在此温度下自由基激发的速度相对缓慢, 因此自由基全部被用于交联反应. 但是在340 ℃热处理时,自由基的浓度则急剧增加,这说明在此温度下自由基产生的速度极快甚至也产生了其它种类自由基,虽然聚合物也发生了交联反应,但是有大量自由基剩余而不利于材料的进一步使用. 恒温热失重结果说明在260 ℃热处理的1, 4-PEEKNK未发生裂解反应. 通过以上结果,给出了1, 4-PEEKNK在260 ℃热交联的交联反应机理.  总之,我们合成了两种不同萘环化学环境及不同键连接方式的聚合物,对其基本性质进行了研究,并且发现两种聚合物在空气中于一定温度下热处理时都发生了交联反应,但交联方式及交联机理各有不同. 就综合性质及应用要求而言,我们认为1,4-萘二酮型聚合物PEEKNK作为全芳香性可交联聚芳醚酮类材料应具有很好的应用前景.     

聚丙烯酸水溶液及α-A12O3悬浮液的流变性研究

研究了pH、聚丙烯酸（PAA）浓度和分子量对PAA水溶液的粘度的影响,发现溶液的流变行为与溶液中PAA高分子链的离子化程度和构型密切相关,高分子链刚性程度的增加和链的伸展使溶液在pH为7－9时的粘度最大;研究了在PAA溶液中引入陶瓷粉体后悬浮液的粘度变化,发现当陶瓷粉体和PAA的量达到一定比值时悬浮液体系的粘度达到最小值,同时发现陶瓷粉体的粒径大小与这一粘度最小值和悬浮液流变特性也有关。     

LJ流体非牛顿现象的分子动力学模拟

使用非平衡分子动力学模拟方法研究了单原子LJ流体的非牛顿流变行为,并在系统中分别施加稳态Couette流场和振荡剪切流场.在Couette流场的模拟中,流体出现剪切变稀和法向应力差效应,不同剪切率下的径向分布函数反映了流体分子由于剪切所导致的微观结构变化,通过分析势能函数发现当剪切率增大时,分子间排斥作用增强,吸引作用减弱.在振荡剪切流场的模拟中,发现剪切应力和剪切率之间的相位差随频率增加而增加,随频率增加复数粘度的实部先增大再减小,虚部单调增加,导致虚部粘度相对实部粘度比例增大,弹性模量和粘性模量之比也随频率增加而增加.这三点现象表明LJ流体出现粘弹性行为,且在高频率下,弹性所占比重增大.     

主链含萘酰亚胺的聚芳醚型聚合物的合成及其光电性能

萘酰亚胺衍生物是一类发光效率优良的电子传输型电致发光材料。本文采用亲核取代反应将其作为聚合物主链的一部分构成主链含1,8-萘酰亚胺的聚芳醚型发光聚合物(PENI),聚合物的重均分子量为4 300。通过FT-IR和NMR对单体及聚合物的结构进行了鉴定,并研究了其光致发光性能和电化学性能。在分子量较小时,PENI薄膜的PL发射峰位于407,456,530 nm;当聚合物分子量提高后,发射峰红移14 nm左右。采用循环伏安法测得聚合物的HOMO和LUMO分别为-5.64 eV和-2.93 eV,E_g为2.71 eV。     

Ab initio研究尿素分子的非线性光学极化率

用ＣＰＨＦ法研究了ａｂ ｉｎｉｔｉｏ计算尿素分子的极化率、一阶超极化率和二阶超极化率时,基函数及分子构型对计算结果的影响。结果表明,在基函数中引入极化和弥散函数对计算值有较大影响,而不同水平上得到的分子构型引起的差异较小。并用ＴＤＨＦ法分别计算了外场频率为７０和１０６４ｎｍ时分子的动态极化率和超极化率。     

普洱茶茶褐素类主要组分特征及光谱学性质研究

利用不同分子截留量的透析袋可有效将茶褐素类物质分离。随分子量增大,茶黄素(TF)、茶红素(TR)、茶褐素(TB)、茶多糖(TPS)含量逐渐增加,分子量大于25 000Da的样品中TB含量最高。羧基和羟基含量随分子量增大而增加,特别是总羧基含量在分子量大于25 000Da的样品中增幅最大。AFM显示,不同分子量茶褐素粒子形貌并不均一,单分子呈岛屿状态或颗粒状聚集物结构。当粒子聚集较多时,呈线状链接且有较多分支或形成网状结构。CP-MAS NMR表明,在3 500～25 000Da的茶褐素属含有多苯环的苯多酚类高聚物,结合多糖、蛋白质残基,富含羧基、羟基、甲基等基团,具有酚类物质特性。其酸未水解物经CP-MAS NMR分析表明为多苯环高聚物,CP-GC/MS共鉴定出16种可能存在的化合物。     

用于质子交换膜材料的侧链型磺化聚芳醚酮砜的光谱分析

采用直接缩聚的方法,通过调整氨基单体用量,合成出了系列带有不同氨基含量的聚芳醚酮砜(Am-PAEKS)聚合物,在聚合物侧链上进行后磺化接枝制备出了系列不同磺化度的侧链型磺化聚芳醚酮砜(S-SPAEKS),并且通过调整磺酸基团含量来控制聚合物的磺化度。通过红外光谱(FTIR)和氢核磁谱(1HNMR),对所合成的单体及其聚合物的结构进行了表征,S-SPAEKS红外光谱在1 239和1 060 cm-1处出现了磺酸基团中OSO的特征吸收峰,氢核磁谱中1.64 ppm处出现了处于烷基链中间位置的两个氢(—CH₂—CH₂—)化学位移,证明得到了S-SPAEKS聚合物。经热失重分析发现,聚合物中磺酸基团的脱落温度都高于240 ℃,聚合物主链降解温度都高于450 ℃。研究表明,该系列聚合物具有良好的热性能,可以用作质子交换膜材料。     

Inductively coupled plasma—atomic emission spectrometry (ICP-AES): an analytical technique for the chemical characterization of perovskite ceramic semiconductors

The possibilities of inductively coupled plasma-atomic emission spectrometry (ICP-AES) for the chemical characterization (dopants, impurities, and macroconstituents) of perovskite ceramic semiconductors (PTC thermistors, varistors, manganites, cobaltites) are shown. The dissolution of the samples is achieved by five methods: (a) decomposition with HCl in a Teflon-lined pressure vessel, (b) decomposition with HF + H₂SO₄ in a Teflon-lined pressure vessel, (c) decomposition with (NH₄)₂SO₄ + H₂SO₄ in a platinum dish, (d) fusion with Na₂CO₃ + Na₂B₄O₇ in a platinum crucible, (e) fusion with Li₂B₄O₇ in a graphite crucible. The spectral interferences and the inter-element effects are studied and corrected. The detection limits are comprised, approximately, between 0.00001% and 0.1%. High sensitivity and good precision are attained.     

Ab initio Study of Electronic Structure and Magnetic Properties of Two Novel Neptunium （V） Sulfates： iaK3（ipO2）4（SO4）4（H2O）2 and iaipO2SO4H2O

Ab initio within the full potential linearized augmented plane wave （FP-LAPW） method with the GGA＋U approach is applied to study the electronic structures of two compounds NaK3（NpO2）4（SO4）4（H2O）2 and NaNpO2SO4H2O. The present calculations show that the major part of the spin magnetic moment in these two compounds is from Np（V） ions, and the origin of the cation-cation interactions between Np comes from the spin polarization effect within Np-ONv-Np bonds.     

Coulometric titrations of electrolytes in water by a solid state ionic device using Nafion and Tosflex membranes

A solid state ionic device to titrate electrolytes in water was produced, and the performance of the device was examined. The device named the coulometric titration apparatus is a three-component electrochemical cell like an electrodialyzer. The central component, the analyzing room, is a container of the sample solution. The sample solution, 10⁻¹ M H₂SO₄, NaOH, Na₂SO₄, or 10⁻⁷–10⁻² M Na₂SO₄, is separated from the cathode and the anode room solutions, 10⁻² M H₂SO₄, NaOH, or Na₂SO₄, by Nafion-117 and Tosflex IE-SF34 membranes working as the anion and the cation blocking electrodes, respectively. The quantity of electricity to extract whole electrolytes in the sample solution is evaluated from the peak area of the titration curve. The sample concentration is successfully determined by the calibration curve method, with the quantity of electricity and the sample volume (6 ml) in the range from 10⁻¹ to 10⁻⁵ M.     

Characterization of Spanish sepiolites by high-resolution solid-state NMR

²⁹Si NMR (MAS and CP/MAS) and ¹H MAS NMR techniques were used to characterize four sepiolites, two of natural origin (commercialized under the names Pangel and Pansil) and the other two obtained from them by treatment with 2 M or 4 M H₂SO₄, respectively. These techniques were used to identify the structural and surface changes undergone by sepiolites by the effects of acid treatment and calcination. Various types of Si were detected; also, treatment with 4 M H₂SO₄ destroyed the sepiolite and produced fibrous silica.     

Potential-induced structure transitions in self-assembled monolayers: ethanethiol on Au(1 0 0)

We have characterized the structural behaviour of ethanethiol self-assembled monolayers (SAMs) on Au(1 0 0) in 0.1 M H₂SO₄ as a function of electrode potential, using in-situ scanning tunneling microscopy (STM). After modification of the Au(1 0 0) electrode in an ethanolic solution of ethanethiol, STM images in air reveal a disordered thiol adlayer and a surface that is covered by 25% of monoatomic high gold islands, which originate from lifting of the (hex) reconstruction during thiol adsorption. In contrast to alkanethiol SAMs on Au(1 1 1), no vacancy islands are seen on the Au(1 0 0) surface. After contact of the SAM-covered Au(1 0 0) electrode with 0.1 M H₂SO₄ under potential control, two different structures are observed, depending on the potential range positive or negative of +0.3 V vs. SCE. In both cases the emerging ordered structures are quadratic, their unit cells being rotated by 45° with respect to the main crystallographic axes of the substrate. However, the ordered structure at negative potentials is more densely packed than the one at positive potentials, and in addition the surface reveals an almost 50% coverage of monoatomic high gold islands. The structure of the SAM changes reversibly with the electrode potential, the long range order gradually decreasing with each transition. Concomittant with this structure transition monoatomic deep holes are created when the potential is stepped from the cathodic to the anodic region. The experimental observations are rationalized by a high mobility of the gold thiolate moiety, causing the surface density of the SAM-covered gold to change drastically with potential.     

2,4,6-三吡啶基三嗪-芳香羧酸镝配合物的合成及其荧光性能

分别以2,4,6-三吡啶基三嗪( TPTZ)、对羟基苯甲酸和对苯二甲酸为配体,以Dy3+为中心合成了不同组成的5种配合物.对其进行了元素分析、紫外光谱、红外光谱、荧光激发和发射光谱的测定.推测配合物的组成分别为:(1)Dy(TPTZ)(NO3)3(C2H5OH)·H2O; (2) Dy (TPTZ)2 (NO3)3 (...     

(NH4)2SO4，NH4NO3和(NH4)2SO4/NH4NO3混合气溶胶吸湿质量增长因子的快速测量方法

气溶胶颗粒的吸湿性决定了其尺寸、浓度、化学组成以及相态,从而显著影响着全球气候、大气异相化学以及人类健康。运用在线、原位、连续扫描衰减全反射傅里叶变换红外光谱（ATR-FTIR）技术, 结合线性湿度（RH）控制系统,实现了RH连续变化条件下气溶胶FTIR-ATR光谱的快速测量。根据水弯曲振动谱带（~1 640 cm-1）峰面积随RH的变化,得到了(NH₄)₂SO₄,NH₄NO₃和(NH₄)₂SO₄/NH₄NO₃混合气溶胶的质量增长因子（MGFs）、潮解点（DRH）和风化点（ERH）。与气溶胶的E-AIM模型预测值相比较,实验结果表现出良好的一致性,证实该方法是一种测量大气气溶胶MGFs,ERH和DRH的快速测量方法。     

The pH dependence of fluorescein fluorescence

Fluorescence quantum yields Φ_f and corrected fluorescence spectra were determined for fluorescein over a wide pH range (10 M H₂SO₄ to 0.01 M NaOH) in aqueous solution. The results were interpreted by comparison with those obtained for the very similar dye 6-hydroxy-9-phenyl-fluoron (HPF) which lacks the fluorescein carboxyl group. We find for the fluorescein cation Φ_f = 0.9−1, for the neutral molecule Φ_f = 0.20−0.25, and for the monoanion Φ_f = 0.25−0.35. The neutral molecule and monoanion have identical fluorescence spectra: an emission with maximum at 515 nm, extending to about 700 nm. (The dianion also has a maximum at 515 nm but has a more narrow emission band.) The fluorescein cation dissociates in the excited state at an acidity corresponding to that of ≈3 M H₂SO₄. A detailed scheme of the protolytic reactions of fluorescein in the excited state is presented.     

Star-shaped oligo(ethylene glycol) ethers (OEGE) as a new type of plasticizer for polymer gel electrolytes

Star-shaped oligo(ethylene glycol) methyl ethers (three and four arm molecules of various molecular weights) were synthesized and characterized with regard to viscosity, thermal transitions, ability to solvate the electrolyte LiCF₃SO₃ and the ionic conductivity of their LiCF₃SO₃ solutions in comparison to linear oligo(ethylene glycol) methyl ethers. Polymer gel electrolytes were prepared by photopolymerization of tri(ethylene glycol) dimethacrylate (EG₃DMA) or its copolymerization with the polar comonomer cyanomethyl methacrylate (CyMA) in the presence of the oligo(ethylene glycol) ethers mentioned above and of the electrolyte LiCF₃SO₃. The gels were characterized concerning their thermal transitions, thermo-mechanical properties, their ability to solvate the electrolyte and their ionic conductivity. In comparison to the linear plasticizers the star-shaped ones show a distinctly lower tendency to crystallize, which is even completely suppressed in several cases. Intensified ion association was found in LiCF₃SO₃ solutions of the star-shaped plasticizers, if the number of the ethylene glycol units per arm was lower than 4. Therefore, the conductivity of the solutions and the gels was lower than that with linear plasticizers at room temperature. The modification of the polymer matrix by copolymerization with 20 mol% CyMA resulted in a maximum of the ionic conductivity σ≈1×10⁻⁵ S/cm of gels with star-shaped plasticizers at 25 °C.