裂解气相色谱讲座第三讲在高分子分析和研究中的应用（上）

裂解气相色谱法(PGC)在高分子领域日益得到人们的重视和广泛的应用,成为一种分析和研究高分子的有效的方法。这一方法不仅在科学研宄机构和大专院校的有关实验室中应用,而且在许多公司、企业、公安司法检验机关等单位的实验室作为材料分析的主要方法之一,在不少工厂作为生产和加工过程的质量检验和控制的重要手段。国外已将此技术制定为橡胶分析的国际标准,国内也已先后制定为橡胶和塑料分析的国家标准方法。PGC法除了用于高分子材料的主成分分析外还可用来分析材料中所含有的低分子化合物,例如残留单体、溶剂以及各种添加剂如增塑剂、防老剂等(称作热蒸发或闪蒸分析)。在用作实际高分子材料分析的这一方面外,PGC法另一个重要的应用方面,是对原料高分子进行结构表征,裂解产物分布,热稳定性,裂解机理和动力学,以及加工过程中变化规律等基础研究。这一讲将对这些方面进行扼要的阐述。     

高分子药物学的研究进展与期盼

自从20世纪70年代提出高分子前药的概念以来,伴随着纳米技术的发展,"高分子药物学"作为高分子科学和材料学、纳米科学、药物学、临床医学、分析科学的交叉学科,正在悄然形成.本文综述了近年高分子药物在药物化学、制剂学、药效学等方面所取得的进展,概述了高分子药物的药理学和药代动力学与小分子药物的区别与联系,指出了高分子药物药效学、药理学和药代动力学研究中的难题和瓶颈,特别是高分子药物可能存在的"三种状态"及从"纳米颗粒药"到"单个高分子药"再到"小分子药"的转变,分析了高分子药输送过程中存在的多重屏障如毛细血管壁、细胞外基质和细胞壁等,阐述了高分子药物的"生理靶向"和"EPR"效应的竞争,指出了高分子药在靶向输送和逆转耐药方面的优势,强调了发展相关分析方法的必要性,期盼高分子科学家与药物学家进行真诚有效的合作,大力促进我国高分子药物学和高分子药物产业的创新和发展.     

技术对经济发展的推动作用—回顾和展望

罗伯特·阿诺德博士是美国杜邦公司高分子部的研究主任,主要负责高分子材料研究的长远规划、研究工作及实验中心的管理。阿诺德博士在工业界工作了近40年时间,在高分研究工作、产品开发等方面积累了丰富的经验。在本文中,作者精辟阐述了自工业革命以来技术对经济发展的促进作用,分析了材料科学,特别是高分子材料对经济发展的贡献,总结了作为有效技术的必要条件,提供了许多有价值的意见。     

浅谈高分子辐射化学的特点

通过对高分子辐射化学与高分子化学的比较，重点阐述了辐射聚合的特点，并简要介绍了辐射接枝和辐射交联与裂解方面的优点，使人们了解到射线不仅仅有破坏作用，更具有许多对人类有益的一面     

Maillard反应的高分子产物的研究进展

Maillard反应产物由于其天然性和独特的香味,使其在食品和烟草领域的应用倍受关注.目前,对Maillard反应产物中的小分子化合物的研究已经比较透彻,但是高分子产物的结构及形成机理尚不清楚.虽然Maillard高分子产物及其复杂,但人们通过膜透析、凝胶柱层析等分离方法,对其提纯分级后,再运用凝胶渗透色谱、元素分析、放射性同位素标记、紫外-可见光谱、红外光谱、核磁共振(NMR)、热裂解等分析手段对其进行表征,对Maillard高分子产物的结构和形成机理有了一定的了解.本文对Maillard反应的高分子产物的分离提纯方法、分析表征方法和分子结构的假设模型三方面的研究进展进行了综述.     

热分析技术及其在高分子材料研究中的应用

简要介绍了热分析技术——热重法、差热分析、差示扫描量热法、热机械分析法和动态机械热分析法等及其在高分子材料领域的广泛应用。热分析技术的方法具有快速、方便等优点,在高分子材料的研究中发挥着重要作用。     

高分子化学课程教学改革与实践初探

高分子化学是高分子材料专业最重要的专业技术基础课之一,既包含了理论基础知识,又注重实验教学。《高分子化学》作为贵州大学高分子材料与工程专业的主干课之一,作者针对高分子化学课程教学内容多、概念多、推导多、关联多等问题,对高分子化学教学现状进行了分析,从教学体系、教学内容、教学方法、考核方式、教材编写等多个方面提出了课程教学改革的一些见解。实践表明,高分子化学课程教学改革与实践探索在激发学生兴趣,提高学生的综合能力上已经初见成效。     

高分子链超声裂解新的Monte Carlo算法

设计了一种新的Monte Carlo算法，在计算机上模拟了高分子链的超声裂解过程。首先根据Ovenall模型用遍历法对高分子链进行模拟断裂，随后进行倒接，进而反演了整个裂解过程。在获得大量模拟结果的基础上，分别研究了极限断裂次数的频率分布，最可几极限断裂次数与聚合度之间的关系，极限断片长度的平均分布，以及分子量多分散系数与裂解程度之间的关系。     

X射线吸收精细结构技术在高分子及相关材料中的应用

高分子材料由于其优异的物理和化学性能应用范围非常广泛,而同步辐射光源的发展大大提高了X射线吸收精细结构(XAFS)技术的使用.本文介绍了XAFS包括扩展X射线吸收精细结构(EXAFS)和X射线吸收近边结构(XANES)的实验原理和实验手段,综述了同行利用XAFS技术在常见高分子、有机金属高分子、钯掺杂高分子、离聚物及碳基材料等高分子领域的结构研究进展,展示了XAFS技术在高分子及其相关材料领域的重要作用和分析方法,体现了XAFS技术的优势和特点,并对XAFS技术在高分子及相关材料方面的应用进行了展望.随着同步辐射技术的发展和提高,XAFS技术在高分子领域的应用将会进一步拓展和提升.     

从高分子化学与衣食住行到高科技发展

本文围绕国际化学年的主题,介绍高分子科学与人类衣食住行、国民经济各个方面的密切关系,结合高分子发展历程、高分子产业现状和高分子学科前沿与发展趋势,概述了高分子科学与技术的基本情况。     

Reproducibility in pyrolysis: Recent developments

Although it has been used as an analytical tool for decades, pyrolysis is still frequently ill-applied to the analysis of solid samples by gas chromatography. The question of reproducibility is fundamental to the utility of any analytical technique, and the practitioners of these techniques must investigate means of providing greater reproducibility. The question of reproducibility as it applies to the analysis of solid materials by pyrolysis-gas chromatography is discussed. Sources of non-reproducible results will be examined from three views: first considering irreproducibility introduced by the entire analytical scheme, including parts of the instrumentation not directly involved with the pyrolysis of the sample; second, concerning the actual pyrolysis of the sample by the pyrolyzer; and finally a look at some recent advances made to reduce or eliminate the sources of irreproducibility.     

STUDY ON THE GASEOUS PRODUCTS OF HIGH TEMPERATURE PYROLYSIS OF ACRYLONITRILE POLYMERS BY ON-LINE FTIR METHOD

The gaseous products of high temperature pyrolysis (300℃ to 960℃) of aerylonitrile polymers were measured continuously under nitrogen atmosphere by on-line Fourier Transform Infrared Spectroscopic method (FTIR). From the variations of characteristic peaks it was found that the nitrogen of macromolecules evolved were mainly in the form of hydrogen cyanide and ammonia. During the pyrolysis amorphous carbonaceous element was formed, and crosslinked to form network structure. Three kinds of samples were used for comparison. The experimental results show that the gaseous products of volatile small molecules were HCN, NH_3, CH_4, C_2H_6 and cyanide. CO and CO_2 were also formed when copolymers of PAN were thermally pyrolyzed.     

Development and Applications of an Automated In-Column Pyrolysis Gas Chromatography-Mass Spectrometry System

A novel system for sample introduction into a Gas Chromatograph (GC) using an automated in-column pyrolysis device has been developed. The in-column pyrolysis device is suitable for use with any GC or GC-MS system. Solid samples are dissolved or emulsions can be diluted and injected into the system. Because the system is designed for introducing liquid samples, a better control of the injected sample amounts is achieved. This leads to high reproducibility of the peak areas, offering new opportunities for quantitation of polymers or other high molecular weight materials. In addition, a better statistical representation of the material to be analyzed is given if the samples are dissolved in a solvent. The system can be operated both in a normal GC injection mode, and in the pyrolysis mode. As a conventional GC injector working in on-column or Programmed Temperature Vaporization (PTV) injection mode, (without the pyrolysis function), information on the volatile fraction of a sample can be obtained. Once the volatile materials in the sample have been separated, a second analysis on the non-volatile matrix can be performed by initiating the pyrolysis sequence, yielding information on the non-volatile fraction of the sample. Both features, on column or PTV injection mode and in-column pyrolysis can be used separately or in combination. This new technology is expected to be useful for the determination of additives, monomers, solvents and other volatile components in a non volatile matrix, such as polymers, as well as in the characterization of the non-volatile matrix itself, in a single run. Revised: 20 June and 21 July 2005     

A new method to analyze copolymer based superplasticizer traces in cement leachates

Enhancing the flowing properties of fresh concrete is a crucial step for cement based materials users. This is done by adding polymeric admixtures. Such additives have enabled to improve final mechanicals properties and the development of new materials like high performance or self compacting concrete. Like this, the superplasticizers are used in almost cement based materials, in particular for concrete structures that can have a potential interaction with drinking water. It is then essential to have suitable detection techniques to assess whether these organic compounds are dissolved in water after a leaching process or not. The main constituent of the last generation superplasticizer is a PolyCarboxylate-Ester copolymer (PCE), in addition this organic admixture contains polyethylene oxide (free PEO) which constitutes a synthesis residue. Numerous analytical methods are available to characterize superplasticizer content. Although these techniques work well, they do not bring suitable detection threshold to analyze superplasticizer traces in solution with high mineral content such as leachates of hardened cement based materials formulated with superplasticizers. Moreover those techniques do not enable to distinguish free PEO from PCE in the superplasticizer.Here we discuss two highly sensitive analytical methods based on mass spectrometry suitable to perform a rapid detection of superplasticizer compounds traces in CEM I cement paste leachates: MALDI-TOF mass spectrometry, is used to determine the free PEO content in the leachate. However, industrial copolymers (such as PCE) are characterized by high molecular weight and polymolecular index. These two parameters lead to limitation concerning analysis of copolymers by MALDI-TOFMS. In this study, we demonstrate how pyrolysis and a Thermally assisted Hydrolysis/Methylation coupled with a triple-quadrupole mass spectrometer, provides good results for the detection of PCE copolymer traces in CEM I cement paste leachates.     

Pyrolysis methods in organic geochemistry: An overview

In recent years it has been realized by geochemists that pyrolysis techniques can provide successful and rapid analyses of sedimentary organic material, including petroleums, coals, oil shales and their precursors. This article represents an introductory overview of the literature of the last 25 years pertaining to geochemical pyrolysis studies. The overview introduces non-geochemists to the many areas in academic and industrial geochemistry to which pyrolysis in general, and analytical pyrolysis in particular, are applicable.     

同时裂解甲基化气相色谱法鉴别合成胶粘剂

 应用同时裂解甲基化气相色谱法 (Py Me GC)对合成胶粘剂进行了鉴别。采用热丝型裂解器、氢火焰离子化气相色谱仪、FFAP毛细管柱、程序升温方式及季铵盐甲基化试剂 ,对刑事案件中常见的丙烯酸酯类及其改性体、醋酸乙烯酯、聚乙烯醇等合成胶粘剂进行了测定 ,并对样品裂解各主要组分峰进行了GC/MS定性分析 ,同时比较了相同样本用常规裂解气相色谱法 (Py GC)测定的结果。结果表明 :Py Me GC法比Py GC法可获得更多的物质组分信息 ,是一种适用于法庭科学鉴定的方法。     

Recent trends and developments in pyrolysis-gas chromatography

Pyrolysis-gas chromatography (Py-GC) has become well established as a simple, quick and reliable analytical technique for a range of applications including the analysis of polymeric materials. Recent developments in Py-GC technology and instrumentation include laser pyrolysis and non-discriminating pyrolysis. Progress has also been made in the detection of low-level polymer additives with the use of novel Py-GC devices. Furthermore, it has been predicted that future advances in separation technology such as the use of comprehensive two-dimensional gas chromatography will further enhance the analytical scope of Py-GC.     

Rapid methods of polymer and polymer additives identification: Multi-sample solvent-free MALDI, pyrolysis at atmospheric pressure, and atmospheric solids analysis probe mass spectrometry

Polymer manufacturers add antioxidants, waxes, dyes, and other materials to enhance polymer utility or processing. Numerous analytical methods are available to characterize various chemical aspects of polymers including methods interfaced with mass spectrometry (MS) such as pyrolysis (Py), gas chromatography (GC), liquid chromatography (LC), and thermogravimetric analysis (TGA). Current methods work well, but because of the necessity of extraction, chromatography, or thermal methods, most are too time consuming for high throughput analyses which might be necessary in, for example, regulatory laboratories. Here we discuss three MS methods for rapid analysis of polymers; multi-sample MALDI MS which allows rapid analysis of low molecular weight polymers, atmospheric pressure (AP) solids analysis probe MS for direct ambient additives analysis, and APPy MS for polymer identification. The latter methods provide information regardless of the composition or molecular weight of the polymeric material.     

Behaviour of phospholipids in analytical reactive pyrolysis

Checking for the presence of egg in a painting layer allows to decide whether or not it is a tempera. Several already assessed analytical techniques may be used to perform the chemical analysis for the detection of egg in paintings. As an advantageous and alternative methodology for the determination of egg, a new application of analytical pyrolysis, hyphenated with gas chromatography–mass spectrometry (GC–MS) system, in presence of hexamethyldisilazane (HMDS) and tetramethylammonium-hydroxide (TMAH), is reported here. The innovation lays mainly in the choice of new markers for the presence of egg. It is here demonstrated that in art diagnostic tris-TMS-ester and methyl ester of phosphoric acid, generated by the pyrolysis of standard phospholipids and synthetic painting layers containing egg as binding medium, may be used as new markers for identification of egg in tempera layers. The adoption of these new markers in analytical pyrolysis allows to obtain higher analytical performance with respect to classical markers (fatty acids), especially in terms of yield and, as a consequence, in terms of limit of detection.     

裂解气相色谱－红外光谱联用分析聚合物结构（Ⅱ）

采用国产ＳＣ－７型色谱仪及ＪＰ－０１型居里点裂解器、Ｎｉｃｏｌｅｔ１７０ＳＸ红外光谱仪及接口组成的裂解气相色谱－傅里叶变换红外光谱（ＰＧＣ／ＦＴＩＲ）分析仪、ＨＰ－１７型大口径毛细管色谱柱，分析了两个复杂组成的聚合物样品。从主要裂解碎片峰的定性结果及形成机理出发，逐步推出了原样品的组成和结构。常规红外光谱分析方法被用来作为对比，但它获得的信息有限，无法得到能与ＰＷＢＣＧＣ／ＦＴＩＲ分析结果相媲美的结论，充分显示了ＰＷＢＣＧＣ／ＦＴＩＲ用于聚合物分析的优越性。