Ferrocene derivatives supported on poly(N-vinylpyrrolidin-2-one) (PVP): Synthesis of new water-soluble electrochemically active probes for biomolecules

Carboxy-terminated polyvinylpyrrolidin-2-one (PVP) has been used as a new water-soluble and biocompatible polymeric support for a series of ferrocene labeled amino acid and peptide nucleic acid (PNA) monomer derivatives 4-7. The organometallic polymer-conjugates thus obtained are new and potentially useful as water-soluble electrochemically active probes for biomolecules. In view of such application, their electrochemical activity has been evaluated and has proved very high notwithstanding the complexity and bulkiness of the molecule, affording detection limits down to 10⁻⁸ M in the aqueous medium.     

Accelerated hydrolysis of esters catalyzed by receptors, II. Degradation of RNA by polyvinylpyrrolidone

The nonenzymatic hydrolysis of RNA by polyvinylpyrrolidone (PVP) has been investigated. A bell-shaped kinetics was observed when the first order rate constant of the reaction was ploted as a function of PVP concentration, which means the kinetic feature of PVP as a degradative receptor distinct from those of degradative enzymes (e.g., ribonuclease).     

Crosslinking and degradation of PVP hydrogels as a function of dose and PVP concentration

Swelling was performed on dried membranes, normal ones and dried gel to unravel the role of crosslinking and degradation on polymeric structure during drying and hydration process. The comparison of the swelling results suggested that the network were formed only by PVP molecules. The complex mixture of macromolecules showed a irreversible behavior upon drying and hydration, probably as a function of PEG and/or agar entangling in effective physical crosslink. The best network regularity and useful properties was found at 20–30 kGy.     

Mechanical properties of molecular composites. I. Poly (p‐phenylene terephthalamide) anion molecules dispersed in poly(4‐vinylpyridine)

Molecular composites have been prepared by dispersing rigid‐rod molecules of ionically‐modified poly(p‐phenylene terephthalamide) (PPTA anion) in a polar poly(4‐vinylpyridine) (PVP) matrix. For concentrations up to 5 wt % of the rigid‐rod reinforcement, the resulting composites are transparent and possess a single glass transition temperature that increases with concentration of the PPTA anion. The mechanical properties of the molecular composites are found to increase with concentration and to attain maximum values at about 5 wt % of the PPTA anion. The enhancement in properties, and the miscibility induced between the two component polymers, is attributed to the development of specific interactions between the ionic groups of the PPTA anion and the polar units of the PVP matrix. When such interactions are not present, as in composites reinforced with non‐ionic PPTA, the samples are opaque and their properties are significantly reduced compared to those of the PPTA anion/PVP composites. © 1999 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 37: 2201–2209, 1999     

模板法制备定向排列的聚乙烯吡咯烷酮纳米管簇

近年来,随着纳米科学的迅猛发展,对定向生长的纳米碳管、半导体、氧化物及金属纳米线、管等无机材料的制备引起人们广泛的关注．然而对定向生长的聚合物纳米结构材料如聚合物的纳米管、线等的制备,却未见报道．最近,德国马普微结构研究所通过模板法制得了具有取向一致的聚合物纳米结构材料,该材料在化学传感器、药物输送以及微环境研究等方面具有广泛的应用前景．     

Effective chemical route for the synthesis of silver nanostructures in formamide

Poly(N-vinyl-2-pyrrolidone) (PVP) and gelatin protected silver nanostructures are prepared in formamide by simple chemical route. Both PVP and gelatin stabilized silver nanoparticles in formamide lead to the formation of nanostructures of various definite geometric shapes and sizes. The effect of anisotropy on the surface plasmon absorption band is analyzed by monitoring the UV-Visible absorption spectra of gelatin stabilized silver nanoparticles. The particles were characterized by UV-Visible absorption spectra and TEM.     

Na-MMT掺杂对PMA/PVP复合膜结构及光致变色性能的影响研究

将钠基膨润土(Na-MMT)掺入磷钼酸/聚乙烯基吡咯烷酮(PMA/PVP)体系中,利用透射电子显微镜(TEM)、原子力显微镜(AFM)、红外光谱(FTIR)、热重-差热(TG-DTA)、紫外-可见吸收光谱(UV-Vis)、X射线光电子能谱(XPS)等手段对复合薄膜的结构、热稳定性和光致变色性能进行了研究.红外光谱结果表明keggin结构磷钼酸和聚乙烯吡咯烷酮的基本结构在复合膜中仍然存在,复合膜中高分子与质子结合,以阳离子的形式与杂多阴离子成盐.Na-MMT的掺杂未对复合膜中PVP和PMA间的相互作用产生影响,但其掺杂提高了复合膜的热稳定性.在紫外光照下,复合膜由无色变为蓝色,杂多酸被还原产生杂多蓝.Na-MMT的掺杂降低了复合膜的光致变色响应性,这是由于多酸分子与钠基膨润土之间发生阳离子交换作用导致的.     

Novel Amphiphilic Poly(N-vinylpyrrolidone) Block Copolymer: Aggregative Behavior and Interaction with DNA

Summary: Novel block copolymers poly(N-vinylpyrrolidone)-block-poly[(tert-butoxy) carbonyl] tryptophanamido-N′-methacryl thiourea (PVP-b-PTAM-I, II and III) were synthesized by atom transfer radical polymerization (ATRP) in DMF using PVP-Cl as macroinitiator. The structures of the copolymers were characterized by UV-vis and GPC-MALLS. The results revealed that the copolymers with controlled molecular weight and relatively low polydispersity (PDI < 1.34) were obtained through ATRP. By means of dynamic light scattering (DLS) and transmission electron microscopy (TEM), we demonstrated that copolymer PVP-b-PTAM self-aggregated to form spherical micelles in aqueous solution and the size of the micelles increased with increasing hydrophobic contents. The interaction of PVP-b-PTAM with DNA was explored using ethidium bromide (EB) quenching experiments. The interaction between PVP-b-PTAM and DNA markedly depended on both the copolymer concentration and composition. The PVP-b-PTAM-II and III with higher hydrophobic contents exhibited highly complexed DNA ability at low copolymer concentration, such as 0.017 mg/mL, relative to PVP-b-PTAM-I. As the copolymer concentration further increased for PVP-b-PTAM-II and III, they first exhibited a sharply decreased affinity for DNA and then kept steady. The interaction mechanism between the amphiphilic copolymers and the EB-DNA complex was discussed in detail.     

链式钴微米六方片的溶剂热合成及磁性

以十二硫醇和聚乙烯吡咯烷酮（PVP）为结构导向剂、乙二醇和乙二胺为混合溶剂,利用溶剂热技术成功地制备了Co粒子,并用XRD、SEM、TEM、HRTEM及SQUID对材料的晶体结构、形貌及磁性进行研究. 结果表明：Co粒子属hcp相,呈六方片状,直径约为2 μm,厚度约为80 nm,大量的六方片相互交叉连接成链式结构,并且六方薄片由更为细小的丝带状的纳米片（厚度约为10 nm）构成;室温下样品表现出良好的铁磁性特征,其饱和磁化强度Ms、剩余磁化强度Mr及矫顽力分别为126.6 emu/g、13.7 emu/g和163.4 Oe.     

基于PVP和PbSe三维自组装超晶格复合体系的电双稳器件

采用旋涂工艺将PbSe三维自组装超晶格镶嵌在两层聚合物PVP中,制备了基于PVP和PbSe三维自组装超晶格复合体系的电双稳器件,器件结构为ITO/PVP/PbSe三维自组装超晶格/PVP/Al,研究了其电学性能和记忆效应。与参比器件ITO/PVP/Al相比,器件ITO/PVP/PbSe三维自组装超晶格/PVP/Al的电流-电压特性呈现出非常明显的电双稳特性和非易失记忆行为,在相同的电压下同时具有两种不同的导电状态：低电导的关态和高电导的开态。当PVP与PbSe超晶格的质量比为1：1时,器件性能最好,其最大电流开关比为7×10⁴,经过10⁴ s仍几乎无衰减。通过对电流-电压曲线拟合,利用不同的导电模型对器件的载流子传输机制进行了解释。结果表明,PbSe三维自组装超晶格作为电荷陷阱,可以俘获、储存及释放电荷,对器件的电双稳性能能起决定性作用。