树枝状共轭聚合物研究

本文介绍了树枝状共轭聚合物的最新发展,包括全共轭、部分共轭树枝状聚合物及树枝化共轭聚合物的特点及其在电致发光、电极、传感器以及光探测等领域的功能化应用;详细讨论了包括代数、支化单元、端基、核、金属离子的络合等结构因素以及溶剂和浓度等工艺因素对电荷传输的影响;并进一步提出该领域研究前景及有待于解决的问题.     

树枝状共轭聚合物研究

本文介绍了树枝状共轭聚合物的最新发展,包括全共轭、部分共轭树枝状聚合物及树枝化共轭聚合物的特点及其在电致发光、电极、传感器以及光探测等领域的功能化应用;详细讨论了包括代数、支化单元、端基、核、金属离子的络合等结构因素以及溶剂和浓度等工艺因素对电荷传输的影响;并进一步提出该领域研究前景及有待于解决的问题。     

树形聚醚的合成及其应用

树形聚合物高度支化,与线形结构的聚合物相比具有较低的粘度及良好的溶解性,而且其单分子尺寸通常在纳米尺度,在多方面具有广阔的应用前景。树形聚合物通常分为3种,即树枝状聚合物、超支化聚合物和树枝化聚合物。作为树形聚合物的主要一类,树形聚醚由于其良好的化学、物理稳定性,良好的水及有机溶剂的溶解性,以及生物相容性等诸多优点,其合成及应用研究得到了广泛重视。本文对不同种类树形聚醚的合成及其应用作一详尽的综述,包括树枝状聚醚、树枝化聚醚及超支化聚醚3种主要类型,同时报道了作者等在该领域的最新研究进展,并对该领域的研究进行了相应的展望。     

树枝化聚合物的合成、结构表征及其应用

本文综述了由树枝状大分子和线形聚合物结合而形成的一类新型树形聚合物--树枝化聚合物的研究进展,包括树枝化聚合物的各种合成方法、结构表征和形态分析等.同时对树枝化聚合物在催化载体、纳米材料、生化和光电功能材料等领域的应用研究进行了详尽的综述.     

爆炸物检测用荧光聚合物材料

作为荧光传感材料,荧光聚合物不仅具有传感单元多、荧光亮度高、光稳定性好等特点,而且方便制备荧光传感薄膜,易于实现器件化,在爆炸物荧光检测中得到了广泛的研究与应用。近年来,随着荧光聚合物从传统的线型结构向支化和多孔网络结构的拓展,以及各种功能单元的引入,大量的新型荧光聚合物有效地提升了爆炸物检测的灵敏度、选择性和响应速度等性能。本综述从线型聚合物、支化聚合物、多孔聚合物三类体系出发,总结和评述了用于爆炸物荧光检测的线型共轭与非共轭聚合物、树枝状分子与超支化聚合物、无定形与结晶型多孔聚合物等典型体系的分子结构设计策略、功能特点以及传感性能,并展望了荧光聚合物未来在爆炸物检测应用中所面临的机遇和挑战。     

树枝状聚合物的应用研究进展

树枝状聚合物为纳米级单分散性大分子,其独特的分子结构和物理化学性质使之在众多领域有着广泛的用途。本文着重介绍了树枝状聚合物在超分子化学、生物医药、光化学、电化学和催化剂等领域中的应用研究进展。     

温度敏感树形聚合物

温度敏感树形聚合物结合了温敏聚合物对温度具有响应行为的特点以及树形聚合物非线形构造的方式、大尺度、结构易于调节和功能化等特征,在智能材料和生物医药等领域有着重要的研究价值和应用前景。此类聚合物可以通过在树形聚合物表面引入温敏基元、控制聚合物结构的亲疏水比例以及采用温敏基元直接构筑聚合物等方式形成,其温敏性可以通过调控聚合物内部或外部基团的亲疏水性、树枝化基元代数、树形构造方式等得以实现与控制。此外,树形聚合物独特的拓扑结构赋予其与线形聚合物不同的温敏行为及脱水机理。本文综述了包括温敏树枝状大分子、温敏树枝化聚合物、温敏超支化聚合物等不同类型温敏树形聚合物近年来的研究进展,重点介绍这些聚合物的合成方法、温敏行为和拓扑结构对温敏行为的影响,以及在纳米材料、生物医用、分子传感器等方面的应用研究。     

带树枝状侧链聚苯乙炔的合成与结构表征

合成了带树枝状聚苯甲醚修饰基团的苯乙炔单体,在Rh[(nbd)Cl2]2催化剂的作用下得到了侧链带聚苯甲醚树枝的新型聚苯乙炔衍生物,用红外吸收光谱、核磁共振谱、紫外可见吸收光谱和凝胶渗透色谱表征了聚合物的结构.发现聚合物的重均分子量达到了57300,在氯仿、N,N-二甲基甲酰胺、四氢呋喃等有机溶剂中有良好的溶解性能.由于侧链上聚苯甲醚树枝体积庞大,聚合物主链采取立构规整的顺-顺式构象,紫外可见吸收光谱在440nm附近出现了显著的共轭主链的吸收肩峰;立构规整的顺-顺式构象使树枝状侧链形成了对主链保护的"夹套效应",聚合物热分解温度从聚苯乙炔母体的225℃提高到295℃.     

含环糊精链节的拓扑高分子

星形、超支化、树枝状、刷状等具有支化拓扑结构的高分子通常具有不同于直链结构高分子的优异性能。将有客体包合功能的环糊精与其结合构筑环糊精拓扑高分子体系,有望在分子识别、基因传输、药控释放等领域得到应用。本文根据高分子拓扑形态的不同,从星形、超支化、树枝状以及其他拓扑形态环糊精聚合物的合成及自组装构筑等方面进行了总结和评述,并在此基础上展望了基于环糊精的拓扑高分子的研究方向和发展趋势。     

二茂铁基聚合物超分子体系构建和性能的研究进展

二茂铁基聚合物具有独特的氧化还原、电、磁等性能，其构建成超分子体系后在传感器、催化、分子电子学、生物和医学等领域有着广泛的应用前景。本文综述二茂铁基线型聚合物和二茂铁基树枝状聚合物的超分子体系构建和性能方面的研究进展，并对今后的发展方面作一展望。     

Ni(II)‐NTA Modified Poly(ethylene imine) Glycopolymers: Physicochemical Properties and First In Vitro Study of Polyplexes Formed with HIV‐Derived Peptides

Alternative delivery entities are desirable in immunotherapies in which polyplexes are widely formed by electrostatic interactions to induce cellular uptake processes for bioactive molecules. In our study, biocompatible Ni(II)‐nitrilo(triacetic acid)‐modified poly(ethylene imine)‐maltose ( Ni‐NTA‐DG ) is realized and evaluated as complexation agent against His‐tagged peptides using fluorescence polarization and dynamic light scattering. The polyplexes are stable until a pH of 6.5–6.0, and also up to 50 mM of imidazole. A first uptake approach shows that polyplexes lead to an increase in peptide uptake in monocyte‐derived immature dendritic cells. In summary, Ni‐NTA‐DG represents a promising (delivery) platform for forthcoming in vitro applications.

     

树状分子BINAP膦配体的合成及其在不对称氢化中的应用: 结构与性能关系探究

设计并合成了系列具有不同代数以及不同结构的手性树状分子BINAP配体. 以Ru-催化的2-芳基丙烯酸的不对称氢化和Rh-催化的乙酰氨基肉桂酸的不对称氢化为模型反应, 结合圆二色谱分析方法, 系统研究了树状分子催化剂的结构与催化性能的关系. 在2-芳基丙烯酸的不对称氢化中, 发现双边取代的树状分子催化剂表现出明显高于小分子催化剂的催化活性, 反应速度随着树状分子代数的增加而加快, 当反应溶剂由甲苯/甲醇(1∶1, V/V)变为纯甲苯时, 这种树状分子加速效应更加明显; 而单边取代的树状分子催化剂, 由于催化活性中心远离树状分子载体, 因此其催化活性与小分子催化剂几乎相同. 此外, 圆二色(CD)谱研究表明, 双边取代的树状分子配体有不同于单边取代树状分子配体和小分子BINAP配体的Cotton效应, 说明树状分子的引入可能影响到位于其核心的手性配体的微环境. 这些结果显示树状分子载体在催化活性中心周围所构筑的微环境在促进催化剂活性中发挥了关键作用. 这种“微环境效应”还在脱氢氨基酸的不对称氢化中得到了进一步证明. 最后, 通过溶剂沉淀法, 实现了树状分子催化剂与产物的方便分离, 催化剂至少可以回收使用三次, 其催化活性和对映选择性没有任何降低.     

Mechanical properties of blends of PAMAM dendrimers with poly(vinyl chloride) and poly(vinyl acetate)

Hybrid blends of poly(amidoamine) PAMAM dendrimers with two linear high polymers, poly(vinyl chloride), PVC, and poly(vinyl acetate), PVAc, are reported. The interaction between the blend components was studied using dynamic mechanical analysis, xenon nuclear magnetic resonance (NMR) spectroscopy, and tensile property measurements. The data suggest a much higher degree of interaction between components of PVAc-containing blends compared to those containing PVC. © 1998 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 36: 2111–2117, 1998     

Dendritic homopolymers and block copolymers: Tuning the morphology and properties

The synthesis and characterization of dendritic homopolymers and block copolymers of ?‐caprolactone and lactide (L ‐lactide and racemic lactide) were performed with multifunctional initiators in combination with living polymerization and the selective placement of branching junctures in a divergent growth strategy. A hexahydroxy‐functional 2,2‐bis(hydroxymethyl) propionic acid derivative was used as an initiator for the stannous‐2‐ethylhexanoate‐catalyzed living ring‐opening polymerization of ?‐caprolactone, L ‐lactide, and racemic L ,D ‐lactide. Branching junctions at the chain ends were introduced with benzylidene‐protected 2,2‐bis(hydroxymethyl) propionic acid. Subsequent generations were then polymerized, after deprotection, from these star‐shaped macroinitiators. Successive chain end capping and initiation produced three generations of polymers with molecular weights in excess of 130,000 g/mol and narrow polydispersities (<1.20). It was possible to prepare diblock and triblock copolymers with phase‐separated morphologies, and with L ‐lactide or D ,L ‐lactide, semicrystalline and amorphous morphologies were demonstrated. The polymers were characterized by ¹H NMR, ¹³C NMR, size exclusion chromatography, and differential scanning calorimetry. The compositions of the block copolymers and the conformational structures of the optically active polymers were also confirmed by optical rotation measurements. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 1174–1188, 2004     

Preparation and properties of novel aromatic polyamides and polyimides jacked with dendritic fragments

The polycondensation of polymerizable diamines bearing two generations of Percec‐type dendritic blocks with dianhydrides led to the formation of novel aromatic polyamic acids that then were converted into a series of novel aromatic polyimides jacked with dendritic fragments. Their solubility in organic solvents was improved remarkably by the introduction of the dendritic fragments, especially in the case of the polyamides and polyamic acids, and the polymers were soluble in normal solvents such as ethyl acetate, acetone, and chloroform. Their thermal properties were investigated with differential scanning calorimetry and thermogravimetric analysis. The glass‐transition temperatures of these polyamides were lower than those of the conventional aramids. All of the polyamides, polyamic acids, and polyimides bearing the dendritic fragments showed two decomposition stages. © 2000 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 38: 189–197, 2000     

Immunomodulatory Properties of Masticadienonic Acid and 3α-Hydroxy Masticadienoic Acid in Dendritic Cells

Dendritic cells are antigen-presenting cells, which identify and process pathogens to subsequently activate specific T lymphocytes. To regulate the immune responses, DCs have to mature by the recognition of TLR ligands, TNFα or IFNγ. These ligands have been used as adjuvants to activate DCs in situ or in vitro, with toxic effects. It has been shown that some molecules affect the immune system, e.g., Masticadienonic acid (MDA) and 3α-hydroxy masticadienoic acid (3α-OH MDA) triterpenes naturally occurring in several medicinal plants, since they activate the nitric oxide synthase in macrophages and induce T lymphocyte proliferation. The DCs maturation induced by MDA or 3a-OH MDA was determined by incubating these cells with MDA or 3α-OH MDA, and their phenotype was afterwards analyzed. The results showed that only 3α-OH MDA was able to induce DCs maturation. When mice with melanoma were inoculated with DCs/3α-OH MDA, a decreased tumor growth rate was observed along with an extended cell death area within tumors compared to mice treated with DCs incubated with MDA. In conclusion, it is proposed that 3α-OH MDA may be an immunostimulant molecule. Conversely, it is proposed that MDA may be a molecule with anti-inflammatory properties.     

A Convenient Synthetic Method of Metal Dendritic Porphyrins

Metal porphyrins are natural antioxidant reagent1-3. However, due to the characteristics of structures, they are only soluble in inorganic acids and part of polar organic solvents. Thus, it is limited to be used as effective pharmaceutical preparations. T…     

Supercooling measurement in W, Ta, Nb and Re liquid metals by stereophotocalorimetric method

The technique of crystal growth coupled with a stereophotocalorimetric method has been used in a series of supercooling measurements on pure refractory metals. The cooling history of these metals is recorded on photographic films which are calibrated as a function of the temperature. High absolute amounts of supercooling has been observed in W, Ta, Nb and Re liquid droplets. It is noted that the brightness traces of the solidification process for highly supercooled Re droplets evidence of two successive phase transformations (Re cfc to Re hc) shows.We thank the Fonds National de Recherche Scientifiques of Switzerland.     

The glass temperature of dendritic polymers

A theoretical treatment of the glass temperature of dendritic polymers is presented. The influences of polymer backbone, end group, initiator core, branching unit, composition and functionality are discussed. In dendritic polymers the glass temperature is dependent only on the generation number of dendritic growth and thus only on the molecular weight of a dendron, but not on the molecular weight of the whole molecule. It is governed primarily by the backbone glass temperature and depends little on branching functionality. Only minor differences between linear polymer and dendrite are obtained, since the influences of end groups and branching compensate each other to a large extent. © 1995 John Wiley & Sons, Inc.