A two-dimensional infrared correlation spectroscopic study on the thermal degradation of poly(2-hydroxyethyl acrylate)-co-methyl methacrylate/SiO2 nanohybrids

Two-dimensional infrared (2D IR) correlation spectroscopy was applied to study the structural changes occurring in the decomposition of PHEA-co-MMA/SiO₂. Complicated absorption spectral changes were observed in the heating process. 2D IR analysis indicates that during heating, covalent bonds, (Si-O-C), between the polymer and the inorganic moiety were formed, which was the main factor in the improvement in thermal properties of the hybrids such as the decomposition temperatures (T_d). The thermal stability of the hybrids was also studied by solid-state ²⁹Si MAS NMR spectroscopy and TGA tests. Their results complemented each other well.     

Determination of chloride ion in aqueous samples by isotope-dilution Fourier-transform flame infrared emission (ID-FIRE) spectrometry

An isotope dilution method for the determination of chloride ion in aqueous samples is described. The method makes use of the isotopic shift in the rotational lines of the 1–0 band of HCl emitted in the near infrared region of the spectrum by vibrationally excited HCl molecules present in a hydrogen/entrained air flame. Chloride ion in the sample is converted to chlorine gas by electrolysis and swept into a hydrogen/entrained air flame where it is converted into HCl. Because isotope dilution is an absolute method of analysis, matrix effects are minimized, and the chlorine generation step need not be quantitative. With the system described in this paper, samples must contain at least 9 mg of chloride ion per ml, and a 2-ml sample is required. Over the range from 10 to 30 mg Cl⁻ ml⁻¹, the average error was −0.96%, and the average relative standard deviation was 3.3% for seven samples using seven of the more intense lines in the P branch. Compared with standard silver nitrate titrations, the isotope dilution procedure was not affected by such common interferences as bromide ion and iodide ion. The technique was applied to several seawater samples from different regions.     

Thermogravimetric study of polyacrylamide with evolved gas analysis

Dried samples of polyacrylamide in an He atmosphere have been subjected to thermogravimetric analysis in the 30–600°C range, and the evolved gases were monitored by FTIR. Water, ammonia, and small quantities of carbon dioxide are released in the first stages of decomposition (220–340°C), where the polymer chains remain intact and the reaction occurs on the pendant amide groups. In the second stage of decomposition (340–440°C), the majority of the weight loss occurs, and main chain breakdown occurs, releasing carbon dioxide, water, nitrile compounds, and imides. Trapping of the gases in this stage and analysis by GC–FTIR and GC–MS reveals the presence of more than 20 decomposition products, and confirms that a large proportion of these can be assigned to glutarimide and its substituted analogs. Imidization and dehydration reactions on the amide groups, as well as free radical breakdown of the main chains, with inter- and intramolecular hydrogen transfer, can account for many of the products of the decomposition. © 1993 John Wiley & Sons, Inc.     

Incorporation of FT-IR spectral data in a computer-assisted prediction of globular protein structure

Currently, much effort is being directed to the determination of the three-dimensional structure of proteins. Two classes of research are of interest; spectrometric techniques which include Fourier transform infrared (FT-IR) spectrometry, and non-spectrometric prediction schemes. The spectra obtained using FT-IR spectrometry, are analyzed to determine the percentages of alpha-helices, beta-pleated sheets, and non-structured coils in a protein. Unfortunately, FT-IR, as well as other spectrometric techniques, cannot be used to determine the exact secondary structure of a protein reliably. Non-spectrometric prediction methods yield information on the exact secondary structure, but are not always accurate. Most prediction methods relate the primary amino acid sequence to the secondary structure of a protein, allowing sequential secondary structure information for the protein examined to be obtained. The goal of this research is to incorporate FT-IR with a prediction method, resulting in an improvement in the accuracy of the prediction.     

The synthesis of a precursor of polybenzimidazole (PBI) and blends with polyamic acid (PAA)

The precursor of polybenzimidazole (PBI), poly(3,3′-diamino-4,4′-benzidine isophthalamide) (PDABI), was synthesized from poly(3,3′-dinitro-4,4′-benzidine isophthalamide) (PDNBI) by reduction. With increasing temperature, the NH₂ moiety which was protected by SnCl₅^?1 could cyclize and form PBI. Blends with polyamic acid (LaRC-TPI) were prepared. Clear blend films were prepared at up to 400°C. The IR spectra displayed shifts in the NH stretching band, thereby providing evidence for specific interactions related to the miscibility of their cured blends. © 1993 John Wiley & Sons, Inc.     

BaF2/La2O3催化剂上甲烷氧化偶联反应活性氧物种的原位红外光谱

用原位红外光谱研究了BaF2/La2O3催化剂上甲烷氧化偶联反应的活性氧物种.结果表明,催化剂经O2预吸附后,在1 108~1 118 cm-1处出现超氧物种O2-的O-O键伸缩振动峰.经18O2同位素交换实验后,原1 108~1 118 cm-1处谱峰的强度减弱,同时在1 086和1 051 cm-1处出现(O18O)-物种和18O2-物种的吸收峰.同位素交换实验进一步确证了1 108~1 118cm-1处谱峰确为O2-物种的吸收峰.在700℃下,O2-物种能够活化CH4生成C2H4,而且O2-物种的消耗量和C2H4的生成量呈很好的消长对应关系.超氧物种O2-是BaF2/La2O3催化剂上甲烷氧化偶联反应的活性氧物种.     

Y型分子筛骨架外阳离子行为的FT-FIR研究

应用付里叶变换远红外光谱（ＦＴ－ＦＩＲ）方法研究了ＮＨ＾＋４交换、Ｎａ＾＋反交换和不同水蒸汽处理条件对ＮａＹ分子筛骨架外阳离子的影响。结果表明，在ＮＨ＾＋４、Ｎａ＾＋阳离子交换过程中，六方柱笼中Ⅰ位竞争激烈，积极参与交换。骨架外阳离子受影响较大，升温过程中分子筛空穴的吸附水被除去的同时阳离子发生了重新分布。较高温度下分子筛发生脱结构羟基，生成多种形式的铝阳离子。     

红外光谱法观察二茂镧系氯化物与氧及水蒸气的反应

用实时红外光谱法在特制的收池中分别观察了一些二茂镧系氯化物Ｃｐ２ＬｎＣｌ（Ｃｐ＝Ｃ５Ｈ５，Ｌｎ＝Ｈｏ，Ｇｄ，Ｌｕ）和Ｃｐ＇Ｌｕ（Ｃｐ＝Ｃ５Ｈ４ＣＨ２ＯＣＨ３）与干燥氧气及水蒸气的反应，结果证实这些二茂镧系配合物在室温干燥氧气氛中很稳定，但在水蒸气中很快水蒸气的反应，结果证实这些二茂镧系配合物在室温干燥氧气氛中很稳定，但在水蒸气中很快水解。从水解反应的最初始阶段和较后期采得的红外光谱提示可能存在...     

Infrared ellipsometry of interdiffusion in thin films of miscible polymers

A new application of infrared ellipsometry is reported. Specifically, the interdiffusion between thin films of miscible polymers—poly(methyl methacrylate) and poly(vinylidene fluoride)—is detected in a non‐invasive measurement. A novel technique of data analysis for interdiffusion was developed and is described. The validity of the approach is supported by simulations of diffusion in a bilayer. The onset of extensive interdiffusion over a time period of 15 min occurs at a temperature of 160 °C. At a temperature of 190 °C, the data show that complete mixing of a bilayer (850 nm thick) occurs within 30 s, which is consistent with previously reported values of the mutual diffusion coefficient. Infrared ellipsometry is non‐invasive, applicable at elevated temperatures and relatively fast and sensitive. Although, in these measurements, it was unable to determine a concentration profile at the interface, infrared ellipsometry was used successfully to detect when interdiffusion had occurred. Hence, it is a useful means for screening polymer pairs for miscibility. Copyright © 2004 John Wiley & Sons, Ltd.     

咪喹莫特的波谱学数据与结构表征

对咪喹莫特的红外(IR)、紫外(UV)、质谱(MS)、氢-氢相关谱(^1H--^1H COSY)、碳氢相关谱(HMQC)、碳氢远程相关谱(HMBC)予以解析并进行了报道。对所有的^1H NMR、^13C NMR谱的信号进行了归属；讨论了质谱的主要碎片离子的可能的裂解方式和红外特征吸收峰所对应的官能团的振动形式。