Structural studies of excimer laser-induced percolative phase transition on polyimide thin film surfaces

The behavior of electrical conductivity for excimer laser irradiated polyimide films in the vicinity of the critical number of laser shots was described by three-dimensional percolative phase transition model. It is: found that electrical conductivity changed more rapidly than that predicted by the percolation model. Thus, the change in microstructure with increasing number of laser shots was analyzed by FT-IR Raman spectrometry and laser desorption time-of-flight mass spectrometry. It is demonstrated that not only the number but also the average size of graphite particles on the irradiated polyimide film surfaces increased with increasing number of laser shots. These results were helpful to better understand the critical change in electrical conductivity on the irradiated polyimide film surfaces. (C) 2001 Elsevier Science B.V. All rights reserved.

多种谱学方法研究环氧乙烷/四氢呋喃共聚醚的热氧降解

采用电子自旋共振 (ESR)、傅里叶变换红外光谱 (FT IR)和多种核磁共振 (NMR)技术研究了环氧乙烷 /四氢呋喃共聚醚的热氧降解 ,表征了近 2 0种产物结构碎片 ,并对EO和THF两种链节的降解作了定量讨论。共聚醚的氧化降解发生在醚键氧碳上 ,遵循自由基氧化机理 ,最后形成大量的甲酸酯、碳酸酯等酯类以及甲基、亚甲二氧基和醇 ,此外还检测到过氧化氢和半缩甲醛结构。分析表明共聚醚中THF链节的降解程度明显大于EO链节 ,而且降解容易发生在两种链节交替连接处。抗氧剂 2 ,6 二叔丁基 4 甲基酚 (BHT)不仅降低了共聚醚的氧化降解程度 ,还改变了降解产物的结构分布 ,显著抑制了碳酸酯和亚甲二氧基结构的生成 ,相对增加了羟基和端甲基结构

含环己烯氮杂环结构的聚醚砜酮三元共聚物合成

用 1 -甲基 -4 ,5-二 ( 4-氯代苯甲酰基 )环己烯与 4 -( 4-羟基苯基 ) -2 ,3 -二氮杂萘 -1 -酮、4 ,4′-二氯二苯砜经亲核共缩聚反应 ,合成了含环己烯结构的杂环联苯型聚醚砜酮三元共聚物。用FT -IR、1H -NMR、DSC、X -射线衍射等方法对聚合物进行了表征 ,并研究了聚合物的溶解性能。结果表明 ,聚合物是一种具有较高的玻璃化转变温度的可溶性无规共聚物。聚合物含有不饱和双键结构 ,是一种反应性高分子。

LLDPE/LLDPE-g-AA共混物的接触角及红外光谱表征

利用熔融共混的方法制备了线性低密度聚乙烯/线性低密度聚乙烯接枝丙烯酸(LLDPE/LLDPE-g-AA)共混物。用傅里叶红外光谱(FT-IR)和测定接触角的方法对不同LLDPE-g-AA含量的LLDPE/LLDPE-g-AA共混物膜的表面进行了表征。结果表明,随着共混物中LLDPE-g- AA含量的增加,水和甘油等极性液体与共混物表面的接触角下降。依据共混物的FT-IR计算了其羧基峰强度。发现极性液体与LLDPE/LLDPE-g- AA共混物膜表面的接触角越小,羧基峰强度越大。

Synthesis and properties of three tris(1,10-phenanthroline) ruthenium (II) derivatives

Three new asymmetrical ruthenium (II) complexes: [Ru(phen)(2){phen-NHCO(CH2)(4)Br}](PF6)(2), [Ru(phen)(2){phen-NHCO(CH2)(5)Br}](PF6)(2) and [Ru(phen)(2){phen-NHCO(CH2)(10)Br}](PF6)(2) were synthesized, which were confirmed by the technique of FT-IR, H-1 NMR and ESI-MS. The electrochemical and fluorescent properties of three Ru (II) complexes were investigated with cyclic voltammetry and fluorometry.

Synthesis, electrochemistry and fluorescence of four new Ru(phen)(3)(2+) derivatives

Four typical LB monolayer film materials, Ru(phen)(3)(2+) complexes with one ligand attached to different long chain alkyl amides, were designed and synthesized. Their chemical structures were identified by the techniques of FT-IR, H-1 NMR and ESI-MS. Also, UV-Vis, electrochemistry and fluorescence of these complexes are reported.

Sol-gel thin-film immobilized soybean peroxidase biosensor for the amperometric determination of hydrogen peroxide in acid medium

An acid-stable soybean-peroxidase biosensor was devel oped by immobilizing the enzyme in a sol-gel thin film. Methylene blue was used as a mediator because of its high electron-transfer efficiency. The sol-gel thin film and enzyme membrane were characterized by FT-IR, and the effects of pH, operating potential, and temperature were explored for optimum analytical performance by using the amperometric method. The H2O2 sensor exhibited a fast response (5 s), high sensitivity (27.5 mu A/mM), as well as good thermostability and long-term stability. In addition, the performance of the biosensor was investigated using flow-injection analysis (FIA).

Synthesis and characterization of a water-soluble endohedral metallofullerol

A water-soluble endohedral metallofullerol, Pr@C82Om(OH)(n)(m approximate to 10 and n approximate to 10), was successfully synthesized through the reaction of a pure endohedral metallofullerene, Pr@C-82, with a concentrated nitric acid and a subsequent hydrolysis process. The formation of endohedral metallofullerols Pr@C82Om(OH)(n) is thought to involve a NO2 radical formation step, in much the same way as the reaction of empty fullerenes. FT-IR, XPS, and LD-TOF MS techniques were employed to characterize the structure of the endohedral metallofullerol from the above reaction.

TiO_2纳米粉的热处理过程研究

用溶胶凝胶法制备出纳米凝胶粉，于不同温度下热处理形成纳米晶，研究热处理温度对粒子大小、形貌、品相转变及吸附能力的关系．XRD、FT-IR、Raman光谱研究表明200～600℃热处理1h的TiO2纳米晶为锐钛矿相，在700℃热处理的纳米晶为锐钛矿相与金红石相共存，800℃热处理的纳米晶完全为金红石相;TEM、TG、XPS的结果证明热处理温度越高，纳米粒子的粒径越大，吸附能力也越弱.

推进剂组分对聚醚聚氨酯粘合剂热氧降解的影响 (Ⅱ)固体填料和助剂的影响

采用FT-IR和多种NMR技术研究了推进剂中常用的几种填料和助剂对聚醚聚氨酯粘合剂热氧降解的影响。高氯酸铵、奥克托金、铝粉、硝化纤维素、键合剂、碳黑等均不改变聚氨酯粘合剂的降解机理，但表现出不同程序的稳定作用。过氯酸铵的吸附作用使样品始终保持固体形态，而含其它组分的样品在降解过程中逐渐变为液态。在ＮＥＰＥ推进剂的热氧降解过程中，硝酸酯和中定剂逐渐挥发分解，粘合剂发生降解，导致推进剂强度降低。

环氧乙烷/四氢呋喃共聚醚聚氨酯的热氧降解

采用FT-IR和13CNMR、1HNMR技术研究羟基环氧乙烷/四氢 呋喃共聚醚(EO/THF)聚氨酯在90℃空气中降解产物的结构．结果表明，聚醚聚氨酯的热氧降解既有软段的氧化降解，又有硬段的解缩聚过程，同时还存在重聚合反应；并且软、硬段互有影响，硬段中的交联结构和氢键增加了软段的热氧稳定性，而软段降解产生的醇的含量和结构影响硬段的解缩聚和重聚合过程．90℃下聚氨酯 的热氧降解并不发生硬段的氧化反应，也不存在碳化二亚胺和假脲醚结构.

添加剂对EO/THF共聚醚聚氨酯热氧降解的影响

采用FT-IR及NMR技术研究固化催化剂、增塑剂、抗氧剂及聚醚二元醇结构对聚醚聚氨酯热氧降解过程的影响． 增塑剂邻苯二甲酸二丁酯(DBP)在聚醚聚氨酯热氧降解过程中起阻降作用． 而固化催化剂二月桂酸二丁基锡(DBTDL)和三苯基铋(TPB)对聚醚聚氨酯的热氧降解有着截然不同的影响． 以聚乙二醇(PEG)为聚醚二元醇的聚醚聚氨酯与环氧乙烷/四氢呋喃(EO/THF)共聚醚聚氨酯具有相似的降解机理；DBP增塑时PEG聚醚聚氨酯比共聚醚聚氨酯具有较低的热氧稳定性，而硝酸酯增塑时PEG体系比共聚醚体系表现出较高的热氧稳定性.

Miscibility and specific interactions in poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate) and poly(P-vinylphenol) blends

The blends of poly(beta-hydroxybutyrate-co-beta-hydroxyvalerate) (P(HB-co-HV)/poly(p-vinylphenol)(PVPh) were investigated by differential scanning calorimetry (DSC), Fourier transform IR (FT-IR) spectroscopy and high-resolution solid-state C-13 NMR techniques. Single glass transition temperatures existing in the whole composition range indicates that these blends are miscible. The presence of hydrogen bonding between the hydroxyl of PVPh and carbonyl of P(HB-co-HV), shown by FT-IR spectra, is the origin of the miscibility. Furthermore, results obtained by high-resolution solid-state C-13 NMR give more information about the structure of the blends. (C) 1998 Elsevier Science Ltd. All rights reserved.

Macrocyclic oligomeric arylene ether ketones: Synthesis and polymerization

Some novel macrocylic(arylene ether ketone)oligomers were synthesized in high yields by a nucleophilic aromatic substitution reaction of 4,4'-dinitrobenzophenone with bisphenols in the presence of anhydrous potassium carbonate under pseudo-high-dilution conditions. Detailed structural characterization of these oligomers by matrix-assisted laser desorption/ionization-time of flight-mass spectrometry (MALDI-TOF-MS), H-1 NMR and FT-IR confirmed their cyclic nature and the compositions of the oligomeric mixtures was indicated by GPC analysis. Ring-opening polymerization of cyclic oligomers 3a to a high molecular weight polymer with M-w of 52.3 and M-n of 17.2 k was achieved by heating at 280 degrees C for 40 min in the presence of a nucleophilic initiator.

Synthesis and characterization of soluble polyimides from 1,1-bis(4-aminophenyl)cyclohexane derivatives

A series of novel aromatic diamines (1-3) containing kinked cyclohexylidene moieties was synthesized by a reaction of excess aniline and corresponding methyl-substituted cyclohexanone derivatives. The structures of (1-3) were identifield by H-1 NMR, C-13 NMR, and FT-IR. The polymers were synthesized from the obtained diamines and various aromatic dianhydrides by the conventional polycondensation reaction followed by chemical imidization as well as high-temperature one-step polymerization. The inherent viscosities and weight-average molecular weights of the resulting polyimides were in the ranges of 0.55-1.58 dL/g and (7.4-15.2) x 10(4) g/mol, respectively. The prepared polyimides showed excellent thermal stabilities and good solubility. All polymers were readily soluble in common organic solvents such as tetrahydrofuran, chloroform, tetrachloroethane, etc., and the glass transition temperatures were observed at 290-372 degrees C.