大分子在固/液界面的吸附行为及应用

由于链状大分子(聚合物)结构的柔韧性和具有一定内旋自由度,所以当它们吸附于界面时,呈现出独特的性质.文章综述了大分子在固/液界面吸附时的概念、特征及影响因素,并对聚合物吸附的应用做了总结.     

Ziegler–Natta polymerization and the remaining challenges

Polymers have become indispensable in the 21st century, and today we cannot imagine life without them. However, till around the beginning of the last century, the science of polymers was considered a very primitive discipline, and majority of the scientific community did not believe that polymers even existed. Hermann Staudinger, among others, fought a long battle to convince the scientific community that polymers are real and that they are long chain molecular entities. Building on this rational bedrock of polymer science, Prof. Karl Ziegler laid the foundation of ethylene polymerization. As outlined by Dr. Sivaram in his articles on Ziegler and Natta, careful observations and systematic analyses of serendipitous results enabled Ziegler to deveop the enormously significant ‘Mülheim atmospheric polyethylene process’. A decade later, Cossee and Arlman revealed the mechanism of this polymerization reaction, which is called ‘insertion polymerization’. Insertion polymerization is popularly known as the ‘Ziegler–Natta polymerization’, in recognition of its founding fathers. Today, the world produces about 180 million tons of polyolefins annually, and polyethylene or polythene has become a household name.In this article, I shall present an overview of Ziegler–Natta polymerization. I will highlight the mechanism of this reaction, and outline the progress made in the last seven decades using some real-world examples. The last part of this artificle will take a stock of the unresolved challenges posed by Ziegler–Natta polymerization, briefiy discuss current solutions, and reiterate the enormous potential of this seventy-year-old reaction to meet contemporary challenges.     

Influence of surfactant concentration on counter-ion induced solubility of poly（pyridine-2,5-diyl）

INTRODUCTION Preparation and electrical properties ofpoly(arylene)s having π-conjugation system along thepolymer chain are the subject of recent interest(Skotheim et al., 1997; Nalwa, 1997; Yamamoto,2002). Among the poly(arylene)s, poly(p-phenylene),poly(pyridine-2,5-diyl) and poly(thiophene-2,5-diyl)are the most fundamental polymers and had beenextensively studied (Skotheim et al., 1997; Yama-moto, 2002; Nurulla et al., 2001). However, thesepolymers show only…     

聚合物驱转后续水驱时机和方法

以往注聚区块转后续水驱技术政策并没有规范,也没有深入的研究,转后续水驱的时机和方法各不相同;部分区块转后续过早,导致停注聚后含水上升过快,转后续水驱过晚聚合物成本高、经济效益差。该文对以往转后续水驱区块停注聚效果进行对比分析,得出转后续水驱的最佳时机,又根据以往转后续水驱积累的经验,总结出了停注聚的方法。     

SETTING UP A QUALITY SUPPORT UNIT

In June 1990 I was asked by the Principal of the College of St. Mark and St. John to set up an Academic Quality Support Unit. Extensive discussion about important policy issues at the preliminary stage saved time and enabled the Unit to start work efficiently and immediately. First I describe some of the policy issues. Next I describe the Unit's aims and comment on them. Finally I describe the Unit's operation and comment on some operational difficulties.     

浅析大学生攻击性行为的心理成因

马加爵索让本人吃惊之余,也在反思.处于转型时期的部分大学生,存在严重的攻击性心理障碍.本文从攻击性行为的内涵、攻击性行为的心理成因,对大学生暴发出攻击性行为背后所潜伏的心理危机进行分析,希望引起教育界重视,以加强高校心理辅导工作.     

An Interrogation of the “If Only” Mentality: One Teacher’s Deficit Perspective put on Trial

In this article, I interrogate a previous and harmful “If Only” mindset I held as an early childhood literacy teacher. I describe the “If Only” mentality as the idea that if only the parents and families of the students I taught changed, schools and teachers could serve their children better. This deficit way of thinking led to a number of mistakes I made as a still-new, white, middle-class, monolingual Reading Recovery teacher who was unprepared to value the home and community literacies of a population of students and families from linguistic, cultural, and economic backgrounds other than my own.     

茶碱分子印迹PDVB-SO3H/PDVB IPN的合成及热力学性能研究

以茶碱为摸板分子，采用顺序聚合法，合成了分子印迹的大孔磺化聚二乙烯基苯，聚二乙烯基苯互穿聚合物网络（PDVB—SO3H／PDVB IPN），测定了IPN的结构和热力学性能。结果表明，制备的分子印迹聚合物对印迹分子茶碱具有较好吸附作用，且能保持第一网的树脂粒径。通过热力学性能研究，讨论了IPN吸附水溶液中茶碱的机理。     

Narrative multiculturalism

This is the first of three papers based on a 20-month study of teaching and learning in a diverse classroom in a downtown community school in Toronto, Canada. The purpose of the study was to examine teaching and learning in a multicultural classroom and to document successful strategies in working with immigrant and minority students. The three papers detail the process by which this focus on classroom life led to a critique of the literature and to a new way to think about multicultural teaching and learning that I call 'narrative multiculturalism'. In this paper, I explore the place of multiculturalism in education and describe several limitations of the traditional ways of examining the issue. I also outline the understanding with which I began the study and describe the nature of my inquiry. I use my autobiographical experiences of multiculturalism and multicultural research to reflect on the literature of multicultural education. The narrative of my relationship with a teacher participant provides a conceptualization of the field and suggests the nature of narrative multiculturalism.     

The Question‐led Design of a Degree Programme

This article discusses a question‐led approach to the design of a new degree programme in computing and information studies, the Bachelor of Informatics, at Griffith University in Brisbane, Australia. Basic considerations arising from various theories which have given a central place to problems and questions in human activity are outlined. Some implications of these considerations for the role and place of questions in education are discussed in terms of the notions of focussing, opening, and activating. It is argued that these notions are important in understanding education to be, in part, vitally concerned with critical inquiry. The specific context at Griffith University in which the question‐led approach came to be adopted is described, together with an account of a report concerning the planning of a new academic activity in the University which was made available to the planning group at the commencement of planning. The processes by which this approach was implemented in the design phase are described briefly. The resulting design, as it existed shortly prior to the commencement of teaching, is described. The conclusion discusses some issues arising from experience in the design and implementation of this programme, and provides some evaluative feedback from staff and second‐year students obtained during the second year during which the programme was offered (1986).     

Preparation and adsorption behaviors of Cu(II) ion-imprinted polymers

Imprinted polymers were prepared for selective removal of Cu（Ⅱ） ions from metal solutions. Three ion-imprinted polymers were synthesized with methacrylic acid （MAA）, acrylamide （AA） and N,N＇-methylenebisacrylamide （MBAA） respectively as the functional monomers, ethleneglycoldimethacrylate （EGDMA） as the cross-linking agent, 2,2＇- azobisisobutyronitrile （AIBN） as the initiator and Cu （Ⅱ） ion as the imprint ion. The template Cu （Ⅱ） ion was removed from the polymer by leaching with a liquid of a 1：1 volumetric ratio of HCl to ethylenediaminetetraacetic acid （EDTA）. The capacity and selectivity of Cu（Ⅱ） ion adsorption were investigated with the three imprinted polymers and their non-imprinted counterparts. The polymers have a maximum adsorption capacity at pH 7.0. The isotherm of their batch adsorption of Cu（Ⅱ） ions shows a Langmuir adsorption pattern. Imprinted polymers all have a much higher capacity and higher selectivity of Cu（Ⅱ） adsorption than nonimprinted ones. MAA polymer benefits the most from imprinting. Imprinted MAA polymer has the highest selectivity when used to rebind Cu （Ⅱ） ion from an aqueous solution in the presence of other metal ions. Ion imprinting can be a promising technique of preparing selective adsorbents to separate and preconcentrate metal in a medium of multiple competitive metal ions through solid phase extraction （SPE）.     

Preparation and adsorption behaviors of Cu(Ⅱ) ion-imprinted polymers

Imprinted polymers were prepared for selective removal of Cu(II) ions from metal solutions. Three ion-imprinted polymers were synthesized with methacrylic acid (MAA), acrylamide (AA) and N,N'-methylenebisacrylamide (MBAA) respectively as the functional monomers, ethleneglycoldimethacrylate (EGDMA) as the cross-linking agent, 2,2'-azobisisobutyronitrile (AIBN) as the initiator and Cu (II) ion as the imprint ion. The template Cu (II) ion was removed from the polymer by leaching with a liquid of a 1:1 volumetric ratio of HCl to ethylenediaminetetraacetic acid (EDTA). The capacity and selectivity of Cu(II) ion adsorption were investigated with the three imprinted polymers and their non-imprinted counterparts. The polymers have a maximum adsorption capacity at pH 7.0. The isotherm of their batch adsorption of Cu(II) ions shows a Langmuir adsorption pattern. Imprinted polymers all have a much higher capacity and higher selectivity of Cu(II) adsorption than non-imprinted ones. MAA polymer benefits the most from imprinting. Imprinted MAA polymer has the highest selectivity when used to rebind Cu (II) ion from an aqueous solution in the presence of other metal ions. Ion imprinting can be a promising technique of preparing selective adsorbents to separate and preconcentrate metal in a medium of multiple competitive metal ions through solid phase extraction (SPE).     

苏丹红I分子印迹聚合物的制备与识别性能研究

通过分子印迹技术,以苏丹红I为印迹分子,甲基丙烯酸为功能单体,季戊四醇三丙烯酸酯为交联剂,偶氮二异丁腈做引发剂,制备了苏丹红I分子印迹聚合物。利用静态平衡法和Scatchard分析法研究了印迹聚合物和非印迹聚合物对苏丹红I选择吸附性能。结果表明,印迹聚合物对苏丹I具有很好的特异性结合能力,为复杂样品中的苏丹红I的选择性富集及快速检测提供了一条新的途径。     

以碘代乙腈控制丙烯酸酯活性自由基聚合研究

研究了以碘代乙腈退化转移剂的丙烯酸醋活性自由基聚合，实验结果表明：在碘代乙腈的存在下控制甲基丙烯酸甲酯（MMA）的聚合，得到的分子量大（1万-10万），而控制丙烯酸甲醋（MA）、丙烯酸乙醇（EA）、醋酸乙烯醋（VAc）得到的分子量较小（〈1万）．实验得出：[IAN]与EAIBN]之比对控制活性自由基聚合有很大的影响，[IAN]与[AIBN]之比为6：1是有效控制聚合的理想浓度．反应温度为60℃时，转化率随时间的增长而增高，分子量随转化率的增高而增大，成线性关系，分子量的分布较窄（〈1．5）．^1H NMR分析表明，在聚合物主链的末端连有碘，说明碘代乙腈在反应中起退化-转移聚合（IDTP）的作用，通过循环往复的碳-碘键的活化，断裂，再形成而得到最终活性的聚合物。     

Media Exposure on Student Work: Spotlight on Undergraduate Research

Abstract

This paper describes efforts by the author to engage and motivate students in undergraduate research by giving them a large audience and engaging the media in disseminating their work. I provide an introduction to public relations from the point of view of a mathematics professor, and describe some lessons I have learned in my own attempts to engage newsprint, radio, and television sources in stories about undergraduate research in mathematics. After describing some partially successful early attempts, the paper discusses a recent event in which undergraduate research in mathematics became, briefly, a “hot news item” in Central Washington. The paper concludes with some thoughts about the benefits of this type of work to our students and our profession.     

高吸水性树脂的研究进展

高吸水性树脂是一种含有强的亲水性基团并具有一定交联度的功能高分子材料。本文介绍高吸水性树脂的吸水原理、性能特征。重点介绍淀粉系、纤维素系、合成树脂类吸水树脂的研究进展,并对其发展方向进行了展望。     

Polymer nanocomposites

The synthesis of polymer nanocomposites is an integral aspect of polymer nanotechnology. By inserting the nanometric inorganic compounds, the properties of polymers improve and hence this has a lot of application depending upon the inorganic material present in the polymers. Solvent casting is one of the easiest and less time consuming methods for the synthesis of polymer nanocomposites. In this article we present different types of polymer composites, methods of synthesis, characterisation techniques and different applications of polymer composites. A Lagashetty is Head, Department of Engineering Chemistry, Appa Institute of Engineering and Technology, Gulbarga, Karnataka. His research interests are synthesis, characterization and applications of nanomaterials and polymer nanocomposites. A Venkataraman is Head, Department of Materials Science, Gulbarga University, Gulbarga. His research interests are nanomaterials, nanomaterials as sensors, polymer synthesis and polymer nanocomposites.     

Curriculum theory and the question of knowledge: a response to the six papers

In this paper, following some brief introductory remarks, I provide a context to this Symposium by presenting a brief autobiographical account explaining how I became involved in curriculum theory and the idea of a knowledge-led curriculum and how I was led to write the paper under discussion. I then make brief comments on each of the six papers individually, concluding with some thoughts about the implications of the collection of papers as a whole for the future of curriculum theory.     

超临界CO2在高分子合成与制备中的应用

介绍了超临界CO2作为介质在高分子合成与制备中的研究应用.在超临界CO2介质中可以实施氟代单体的均相和非均相聚合,可以用超临界CO2溶胀聚合法渗透小分子添加剂、制备剃度共混物以及对聚合物纤维材料进行染色.此外,超临界CO2还可以用于聚合物微纤和微球的制备.