氯甲基化聚苯乙烯后交联过程中的氧化反应研究

在１２０℃将氯甲基化聚苯乙烯进行Ｆｒｉｅｄｅｌ—Ｃｒａｆｔｓ后交联制备超高交联聚苯乙烯的过程中，伴随有氧气对氯甲基化聚苯乙烯的氧化作用而使超高交联聚苯乙烯含有极性基团羰基约２．５ｍｍｏｌ／ｇ，而在较低的温度下，通过后交联制备超高交联聚苯乙烯时，则没有氧化反应发生。     

制备氯甲基化聚苯乙烯交联微球的新方法

使用Lewis酸催化剂, 用自制的氯甲基化试剂1,4-二氯甲氧基丁烷(BCMB), 在室温下对聚苯乙烯交联微球(白球)进行氯甲基化反应, 制得了氯含量接近17%的氯甲基化聚苯乙烯交联微球(氯球); 通过红外光谱法与佛尔哈德分析法表征了产物的化学结构与组成; 考察了各种因素对氯甲基化反应过程的影响规律. 结果表明, 各种因素对白球氯甲基化过程的影响表现在两个方面: (1) 影响白球的氯甲基化程度; (2) 抑制或促进分子链之间通过Friedel-Crafts反应进一步交联, 影响微球的强度.     

两步后交联法制备氯甲基化聚苯乙烯交联微球

以平均粒径为40μm的非交联氯甲基化聚苯乙烯(CMPS)微球为出发物料,采用水解-轻度交联与重度交联两步骤的后交联方法,制备了氯甲基化聚苯乙烯交联微球.用红外光谱表征了交联前后微球化学结构的变化,使用扫描电镜观察了交联微球的形貌,重,点考察了各种交联条件对微球交联度的影响规律,分析了交联反应机理.结果表明:先将非交联氯甲基化聚苯乙烯微球部分水解并轻度交联,然后使CMPS微球在良溶剂中溶胀,使用Friedel-Crafts催化剂,再度进行交联反应,可顺利地制得氯甲基化聚苯乙烯(CCMPS)交联微球;控制交联反应的条件,如反应温度、反应时间、溶剂性质、催化剂种类与用量等,可获得交联度不同的微球,其球形度依然保持良好.     

超高交联聚苯乙烯吸附剂的合成,结构与性能

本文总结了超高交联聚苯乙烯的各种合成方法，对干态下和溶胀态下超高交联聚苯乙烯的结构进行了评述，并介绍了超高交联聚苯乙烯独特的溶胀性能和优良的吸附性能．引用参考文献３２篇。     

胶束催化作用下实现聚苯乙烯的氯甲基化

用紫外分光光度法测定了离子型表面活性剂胶束溶液对聚苯乙烯四氯化碳溶液的增溶性能; 用胶束催化法实现了聚苯乙烯的氯甲基化, 用红外光谱法和佛尔哈德法表征了氯甲基化聚苯乙烯的化学结构与组成; 通过比较阴、 阳离子表面活性剂及结构不同的阳离子表面活性剂的催化效果, 探索了胶束催化的作用机理, 考察了表面活性剂结构对催化作用的影响规律. 结果表明, 表面活性剂胶束溶液可增溶聚苯乙烯的四氯化碳溶液, 随着四氯化碳在胶束中的增溶, 聚苯乙烯可转移至表面活性剂的胶束中; 胶束催化是实现聚苯乙烯的氯甲基化的有效途经, 仅用3.35 g/L的十六甲基三甲基溴化铵(CTAB),  于65 ℃， 5 h内即可使聚苯乙烯大分子链中的苯环氯甲基化程度达到37%; 聚苯乙烯与甲醛、 氯化氢的反应过程由亲电取代和亲核取代串联而成, 阳离子表面活性剂比阴离子表面活性剂的催化作用更加有效, 说明亲核取代是慢步骤; 阳离子表面活性剂疏水链越长, 对聚苯乙烯的增溶效果越好, 催化作用越强.     

交联聚苯乙烯氨基树脂的结构与脱色性能研究

通过改变交联度、致孔剂以及胺化试剂合成了一系列大孔氨基吸附树脂。详细研究了树脂孔结构、功能基结构与树脂脱色性能的关系。     

大孔交联聚苯乙烯的分形结构研究

采用小角Ｘ－射线散法测定大孔交联聚苯乙烯树脂的结构,发现大多数大孔交联聚苯乙烯在数纳米至数十纳米的标度尺寸范围内具有分形结构,分形维数介于２和３之间。本研究还进一步探讨了交联度、致孔剂,功能基化反应及后处理对大孔交联聚苯乙烯分形结构的影响。     

超高交联聚苯乙烯对非水体系中苯酚的吸附热力学研究

采用“一锅法”以氯化锌为催化剂合成了超高交联聚苯乙烯。测定了超高交联聚苯乙烯对环己烷中苯酚的吸附等温曲线，利用热力学函数关系计算出了吸附焓、吸附自由能和吸附熵，比较了超高交联聚苯乙烯对苯酚和苯甲醚吸附性能的差别，推测吸附过程的主要作用为氢键作用。以小分子化合物为模型，通过分子间相互作用能的计算，论证了树脂是通过其羰基氧原子与苯酚的羟基氢原子之间的氢键作用而吸附苯酚的。     

高度交联聚苯乙烯吸附剂的结构与吸附性能研究

在通过Ｆｒｉｅｄｅｌ—Ｃｒａｆｔｓ后交联反应制备高度交联聚苯乙烯吸附剂的过程中，向反应体系中加入非极性芳香化合物甲苯，当加入少量甲苯时，吸附剂的比表面积、孔容等变小，但其吸附能力却明显提高；当加入甲苯超过某一量时，其吸附能力又随加入甲苯的量的增加而降低，这说明孔结构和骨架结构共同影响着高度交联聚苯乙烯吸附剂的吸附性能．     

起始共聚物的结构对超高交联聚苯乙烯的结构和抗溶胀破碎性能的影响

本文以凝胶型低交联聚苯乙烯为起始共聚物，合成了各种超高交联聚苯乙烯，研究了起始共聚物的化学交联和物理缠结对合成的超高交联聚苯乙烯的表面和孔道结构的影响。此外，本文还以干态超高交联聚苯乙烯加入液体介质中时的碎球率为指标，考察了起始共聚物的结构对合成的超高交联聚苯乙烯机械性能的影响。     

FLUORESCENCE STUDIES ON MORPHOLOGICAL CHANGE OF ST/DVB CROSSLINKED GELS DURING CHLOROMETHYLATION

The morphological change of St/DVB crosslinked gels during chloromethylation wasstudied by fluorescence spectroscopy using St/DVB crosslinked and hypercrosslinked gels as controlsamples. It has been found that with increase of chlorine content, the excimer emission band (～325nm)approaches to vanish, while the intensity of multi-ring aggregate emission band (～420nm) quicklyreaches a maximum, and then decreases sharply accompanied by appearance ofa new broad bandcentred at ca 488nm which roughly coincides with the typical emission band of hypercrossllinkedSt/DVB gels. Mearwhile, the result of IR measurement suggests that methylene bridge between phenylrings forms and increases with chloromethylation process. These results are explained in terms ofaside reaction of post-crosslinking, which densifies the loosely crosslinked networks and undoes thedensely entangled microgel nuclei. As a result, the morphology of the crosslinked gels becom es morehomogeneous with chloromethylation.     

FLUORESCENCE STUDIES ON MORPHOLOGICAL CHANGE OF ST/DVB CROSSLINKED GELS DURING CHLOROMETHYLATION

1. INTRODUCTION Crosslinked polymer gels have solid-liquid dual performance, which play an important role in modern high technology [1]. A wide variety of functional and intelligent materials can be prepared via chemical modification of crosslinked polym…     

SYNTHESIS AND FLUORESCENCE STUDY OF St／DVB COPOLYMERS LABELLED WITH PYRENE GROUPS

ＳＹＮＴＨＥＳＩＳＡＮＤＦＬＵＯＲＥＳＣＥＮＣＥＳＴＵＤＹＯＦＳｔ／ＤＶＢＣＯＰＯＬＹＭＥＲＳＬＡＢＥＬＬＥＤＷＩＴＨＰＹＲＥＮＥＧＲＯＵＰＳＷａｎｇＧｕｏｃｈａｎｇ；ＬｉａｎｇＹｕａｎｆｏｎｇ；ＧａｏＨｕａｎ；ＬｉａｎｇＬｉｊｕｎ；ＨｅＢｉｎｇｌｉ...     

有机电解质在胶束催化聚苯乙烯氯甲基化反应中的作用

在实施聚苯乙烯氯甲基化反应的胶束催化体系中加入四丁基溴化铵 ((Bu)₄NBr, TBAB), 研究了有机电解质TBAB对胶束催化反应的影响规律. 实验结果表明, 在非离子表面活性剂NP-10及阴离子表面活性剂SDS的胶束催化体系中, TBAB的加入使聚苯乙烯氯甲基化反应的速率明显增大, 前者尤为突出；而在阳离子表面活性剂CTAB的胶束催化体系中, TBAB的加入几乎对反应速率无促进作用. 这种结果一方面归因于加入电解质TBAB会降低SDS的临界胶束浓度, 从而增强对聚苯乙烯四氯化碳溶液的增溶能力；更主要的原因是TBAB的丁基与表面活性剂碳氢链间的疏水相互作用会使季铵离子(Bu)₄N⁺嵌入SDS的胶束之中, 结合到NP-10的胶束表面, 使SDS胶束的阴离子头基对亲核取代反应(控制步骤)的禁阻作用得以减缓, 使NP-10的胶束表面携带了正电荷, 显著促进亲核取代反应的进行, 而对于CTAB的胶束, 由于静电排斥作用, 季铵离子(Bu)₄N⁺不能接近CTAB的胶束, 故TBAB的加入对聚苯乙烯氯甲基化反应不产生作用.     

Fluorescence Behavior of Anthracene in Composite System of PBA/PS

The fluorescence emission behavior of anthracene (An) wrapt in the film cast from poly (butyl acrylate)/polystyrene composite emulsion prepared by seed emulsion polymerization was determined. The result shows that the emission spectra are sensitive to the environment of the probe An. The volatilization of solvent under film-forming will enhance the luminous emission.The heat treatment to film will weaken the fluorescence and shift the signals towards higher frequency.     

Studies on Hybrid Organic/Inorganic Nanocomposite Gels Using Photoluminescence Techniques

Summary.  Transparent nanocomposite gels made of hybrid organic/inorganic polymers, synthesized through the sol-gel method, composed of poly-(ethylene oxide) or poly-(propylene oxide) chains, and grafted on silica through urea bridges, have been studied by steady-state and time-resolved photoluminescence techniques. These nanocomposite materials consist of two distinguished subphases, an organic and an inorganic one. The volume fraction of the organic (polyether) subphase is larger than that of the inorganic (silica) subphase, and it increases with increasing polyether chain size. The condensation of the silica subphase provides luminescent entities emitting light by electron-hole recombination on delocalized states associated with the active chemical species of the urea bridges. Materials with smaller polyether chains are more luminescent than such with longer polyether chains. Divalent or trivalent cations introduced into these materials enhance the luminescence intensity by solubilization close to the silica cluster surface and thus by decreasing surface defects and the ensuing quenching mechanism. Received June 23, 2000. Accepted (revised) July 18, 2000     

基于醛基化改性的交联聚苯乙烯微球制备席夫碱型螯合树脂的研究

在缚酸剂Na2CO3存在下,使溶胀的氯甲基化交联聚苯乙烯(CMCPS)微球表面的氯甲基与对羟基苯甲醛(HBA)发生亲核取代反应,制得了醛基(AL)化改性的交联聚苯乙烯(ALCPS)微球;利用所制得的ALCPS微球与甘氨酸(GL)发生缩合反应,制备了同时含有席夫碱配基与羧基的席夫碱型螯合树脂AGCPS微球。采用红外光谱法表征了微球功能基团的结构变化,重点研究了CMCPS微球醛基化改性反应,考察了影响亲核取代反应的主要因素,推测和探讨了反应的机理。研究表明,CMCPS微球表面的苄氯基团与HBA缩合反应的速率与HBA的浓度无关,属于典型的SN1反应;使用极性较强的溶剂DMF,在较高的反应温度(90℃)下,有利于亲核取代反应的进行。所得席夫碱型螯合树脂对铜离子具有较强的螯合吸附能力。     

茚三酮与赖氨酸荧光反应的研究

茚三酮与赖氨酸的显色反应已广泛用于各种样品的测定,但高灵敏的氨基酸荧光测定法的研究还很不够。尽管茚三酮与某些氨基酸的荧光反应已有报道,但反应条件苛刻,反应时间长达60～120min,对赖氨酸的专一测定法尚未见报道^[1~3]。     

Studies on the Fluorescence Enhancement Effect of Eu-La-DBM-DPG-Acetone System

The study of fluorescence enhancement has attracted attention recently. For example, the sensitivity and selectivity of Eu-thenoyltrifluoroacetone (TTA)phenan-throline and Eu-diphacinone-ammonia systems in Triton X-100 micelles are increased by the addition of La~(3+) Gd~(3+), Tb~(3+), Lu~(3+) or Y~(3+). The mechanism of this fluorescence(?)     

Electrical probing of endothelial cell behaviour on a fibronectin/polystyrene/thiol/gold electrode by Faradaic electrochemical impedance spectroscopy (EIS)

The electrochemical impedance spectroscopy (EIS) technique has been shown to be an effective tool for monitoring endothelial cell behaviour on a multilayer functionalised gold electrode. Polystyrene, a reproducible model substrate, is deposited as a thin layer on a thiol functionalised gold electrode. Fibronectin, a protein promoting endothelial cell adhesion, is then adsorbed on the polystyrene surface. The different steps of this multilayer assembly are characterized by Faradaic impedance. The charge transfer resistance and the capacitance for the total layer are modified at each step according to the electrical properties of each layer. This gives the endothelial cells' electrical state in terms of its resistive and capacitive properties. In this study, the endothelial cell layer presents a specific charge transfer resistance equal to 1.55 kOmega cm(2) with no large defects in the cell layer, and a specific capacitance equal to few microF cm(-2) explained by the existence of pseudopods. These electrical properties are correlated to the endothelial cell viability, adhesion and cytoskeleton organization.