聚合物液体的状态方程

本文分析介绍了三个最广泛使用的聚合物液体状态方程，Ｆｌｏｒｙ、ＳＬ和ＳＳ方程及作者开发的三个新方程ＳＨＴ、ＳＨＴＦ和ＯＣＭ的理论基础和假设，并用１５个聚合物液体、１７个大分子量烃液体和６个常用有机溶剂的Ｐ－Ｖ－Ｔ数据作了比较。结果表明，ＯＣＭ方程精度最好，其他方程精度按ＳＳ、ＳＨＴ、ＳＨＴＦ、Ｆｌｏｒｙ、ＳＬ依次变差。结论是开放胞腔更接近液体的真实结构，空穴的引入可以改进胞腔理论的计算精度，Ｌ－Ｊ位能可以较好地反映液体中分子间的作用力。     

高分子离子液体的研究进展

综述了高分子离子液体最新的研究进展。作为离子液体的载体材料主要有两大类 :一是无机高分子 ,离子液体中的阴离子或阳离子通过与无机高分子材料表面的基团键合形成含离子液体结构的高分子 ;二是有机高分子 ,在有机高分子上引入离子液体合成聚合物电解质 ,并介绍了其在催化、导电材料方面的应用前景     

Dynamic Mobility of Two Spherical Particles with Thick Double Layers

The dynamic electrophoretic mobility of a pair of nearby spherical particles is analyzed in the case when the thickness of the electrical double layer around each particle is comparable to the particle radius. By means of an integral reciprocal relation, a formal expression is obtained for the force and torque on N spheres subject to an oscillating electric field which may be spatially varying. Upon linearizing in the surface potential, this expression is shown to depend upon a set of purely hydrodynamic problems involving N neutral spheres, the calculation of the electric field around N neutral spheres, and the equilibrium charge distribution around N charged spheres. In the case of a single particle, the known analytic formula for the dynamic mobility is recovered. For a pair of identical particles, the dynamic mobility is calculated numerically, using known solutions to the required subproblems. An analytical expression for the mobility of a pair of widely separated spheres is also obtained by a method of reflections, and this is in excellent agreement with the numerical results outside the range of double layer overlap. Copyright 2000 Academic Press.     

荧光探针技术在高分子科学中的应用

本文从原理及应用两个方面介绍了荧光探针技术在高分子科学中的应用, 讨论了荧光探针化合物的光化学和光物理行为, 以及如何用该技术来研究高分子的结构特征和高分子体系的动态过程问题, 包括利用该技术来研究高分子体系中的分子运动、能量转移和自由体积等重要例证。     

Preparation of Composite Polymer Particles by Seeded Dispersion Polymerization in Ionic Liquids

Summary: Submicron-sized monodisperse PS particles were prepared by dispersion polymerization of styrene in ionic liquids with poly(vinylpyrrolidone) as stabilizer. Seeded dispersion polymerization of MMA was subsequently carried out with PS seeds in [Bmim][BF₄] to prepare PS/PMMA composite particles. Observation of the obtained particles of ultrathin cross-sections with a scanning and transmission electron microscope revealed that no secondary nucleation occurred during the seeded dispersion polymerization and that the particles have a core-shell morphology consisting of a PS core and a PMMA shell. Successful preparation of PS/PMMA composite particles in an ionic liquid has thus been demonstrated. Moreover, PS/PAA (PS-core/PAA-shell) composite particles were prepared by seeded dispersion polymerization in [DEME][TFSI], illustrating that hydrophobic/hydrophilic composite particles can be readily prepared in the ionic liquid.     

Novel Color-Shifting Mobility Sensitive Fluorescent Probes for Polymer Characterization

1-Methyl-7-dimethylamino quinolinium tetrafluoroborate, a highly stable, highly fluorescent color-shifting mobility sensitive fluorescent probe was employed for detecting the glass transition and phase transitions, notably crystallization, in polymers and polymer blends. Glass transitions in amorphous and semi-crystalline polymers were detected by a change in gradient in emission wavelength λ_max versus T plots. Crystallization resulted in discrete blue shifts in λ_max versus T plots. Selective probing of PMMA in a PS/PMMA blend, down to a PMMA content of 1%, was demonstrated. Dielectric relaxation spectroscopy has established a clear link between the mobility of dipoles in PMMA and the emission wavelength of the fluorescent probe.     

Simulation of Polymer Melts: From Spherical to Ellipsoidal Beads

In a previous work^[1] we presented a coarse‐graining procedure for bonded interactions, while spherical, purely repulsive 6–12 interactions were used to account for the excluded‐volume of the beads of the phantom chains. Here we extend this approach towards ellipsoidal beads whose shapes are extracted from the geometry of the underlying atomistic chains. The influence of the bead shapes on the static and dynamical properties of melts are studied in detail for two modifications of polycarbonates, from 2mers up to 20mers. The results obtained in both cases are discussed in the context of corresponding experiments and atomistic simulations.     

Anisotropic Ionic Mobility of Lithium Salts in Lamellar Liquid Crystalline Polymer Networks

New mesogens presenting smectic A (SmA) phases and capable of hosting lithium salts are designed. The mesogens comprise a vinyl‐functionalized spacer to allow further reaction to the polymer backbone, an aromatic core and ethylene oxide chains, able to coordinate lithium ions. Copolymerizing these monomers with a suitable crosslinker yields the first lithium containing liquid crystalline elastomers (LCEs). The SmA structure where the ethylene oxide chains are microphase separated in layers is fixed by the crosslinking and permanent macroscopic orientation is obtained. Diffusion and conductivity measurements of the monomer sample show a large anisotropy of the ion mobility (100 for the cation and 400 for the anion). In the elastomer the anisotropy of the lithium mobility is comparable to that in the monomers.     

液体的内压力与正规及聚合物溶液理论的修正

用实际液体的内压力取代van der Waals流体的内压力,导得一个修正的Scatchard-Hil-debrand正规溶液理论。检验结果表明,不仅有效地改善了理论对小分子液体混合物气液平衡的预测准确性,而且使理论能够满意地描述聚合物溶液的Huggins参数随溶液浓度改变的实验事实。     

扫描探针显微镜在导电聚合物研究中的应用

扫描探针显微镜在导电聚合物研究中的应用;扫描探针显微镜;导电聚合物;综述     

X‐Band DNP Hyperpolarization of Viscous Liquids and Polymer Melts

NMR studies of synthetic polymers and biomacromolecules, which provide insight into the conformation and dynamics of these materials, can benefit strongly from the increased sensitivity offered by dynamic nuclear polarization (DNP) and other hyperpolarizing methods. In this study ¹H DNP nuclear spin hyperpolarization of two polybutadiene samples, representing a supercooled liquid and an entangled polymer melt, is demonstrated at 0.35 T magnetic field strength and at temperatures between −80 and +50 °C. Electron spin polarization transfer from the α,γ‐bisdiphenylene‐β‐phenylallyl radical to the sample nuclei is achieved by the Overhauser and solid effect. DNP signal enhancements are studied, varying the electron spin resonance offset, microwave power, and sample temperature. The influence of spin relaxation times, line widths, and molecular dynamics are discussed. The results show promising, up to 15‐fold NMR signal enhancements using noncryogenic temperatures and an inexpensive setup that is less technically demanding than current high‐field DNP setups.

     

Silica-graft-polyamidoamine Hybrid Materials: Effect of Constraints on the Polymer Mobility

Organic-inorganic hybrid materials with excellent heavy metal ions chelating properties are synthesized by covalent bonding of multifunctional polymers of polyamidoamine (PAA) type onto silica. Two series of polyamidoamine-silica hybrid materials differing in the PAA chemical structure are prepared and their thermal properties are investigated. Differential Scanning Calorimetry (DSC) is used to study the effects of chain immobilization and ion chelation on the glass-transition temperature (T_g) of the polymers. The T_g of PAA-hybrid materials is elevated with respect to ungrafted PAAs, but when the linear and the corresponding hybrid PAAs are in the complex form with metal ions such as Cu²⁺ and Co²⁺, the materials arrive to the decomposition temperature and no T_g is detected. To highlight the effect of metal ion on the molecular mobility of these systems, an oligomeric plasticizer is added. The behaviour in the T_g region is analyzed and discussed in term of Tool-Narayanaswamy-Moynihan (TNM) model. In particular the apparent activation energy (Δh*) is used to discuss overall segmental co-operativity in order to better understand the effect of complex formation on structural mobility.     

Statistics of Polymer Solutions from Scaling Concepts for Geometry and Relativistic Self-Diffusion in Liquids

Basic results on conformational statistics of polymer solutions are derived from recent scaling concepts for geometry and a relativistic picture for Brownian self-diffusion in liquid media. Any chain conformation is interpreted as a geometrical state affected by its end-to-end dimension, which here denotes the mean deviation between geodesic paths diffusing in the relativistic liquid phase. Statistical polymer length distributions solve an ondulatory equation in non-Euclidean manifolds for coil extension and shape. When length scale is vanishing, the size scaling is found again in terms of parallelism angle rotations. The characteristic chain ratio identifies instead an average metric coefficient, originating topologically from rotational degrees of freedom internal to single molecules.     

Adsorption and Mobility of Water and Benzene Molecules in Carbon and Polymer Adsorbents

The correlation between the adsorption and the mobility of adsorbed molecules was analyzed. The peculiarities of molecular mobility in microporous adsorbents with relatively rigid (active carbons) and non-rigid (polymer super-crosslinked and methacrylate sorbents) structure were studied using pulsed nuclear magnetic resonance (NMR) techniques. It was shown that the translational behavior of water and benzene in pores are connected with the specific adsorption mechanism. The NMR data allowed analyzing the changes of molecular state in the processes of adsorption. Diffusional properties of water molecules in the super-crosslinked polystyrenes and active carbons with relatively rigid framework are similar and differ from that in methacrylate polymer sorbents. Moreover, the results of NM relaxation measurements allowed analyzing the porous structure over the scale of pore sizes, while the scale of the self-diffusion measurements comprises the areas of different porosity. The NMR data agree well with the data of adsorption measurements and complement them. Dedication: This work is devoted to memory of the professor W. Schirmer.     

Entanglement of Polymer Chains in Concentrated Region by Fluorescence Probe Technique

Fluorescenceprobetechniquehasbeenusedtostudyconformationalpropertiesaswellasdyllamicsandmorphologyinpolymersystemsinthepastdecadesl.Theratioofexcimertomonomerintensitiesismostoftenusedtocharacterizethefluorescencepropertiesofpolymer.Qianatap.demonstratedbyexcimerformationofphenylgroupsthatthepolymerconcentrationwasrangedbytwocriticalconcentrationsofC,andC'.Itisshownthattheratioofexcimertomonomerintensitiesmerelyincreaseslinearlywithconcentrationinconcentratedregion.Sinceexcimerformationisadif…     

A Procedure for Rational Probe Liquids Selection to Determine Hansen Solubility Parameters

Hansen Solubility Parameters (HSP), viewed in the context of similarity whenever dispersion is focused, offer valuable insights into the surface characteristics of nanoparticles. However, existing methods for determining HSP via the sedimentation of nanoparticles require multiple probe liquids, resulting in time-consuming, costly experiments with potential health risks. To address this, we developed a two-step strategy that enables a systematic selection of liquids. The key element of the approach is to first identify the rough location of the Hansen sphere in the three-dimensional Hansen space using a well-chosen set of probe liquids of different polarities and chemical structures. Then, depending on the outcome of the first step, a particular choice of liquids is made for the final HSP determination. Taken together, the introduced procedure reduces the amount of required liquids for experiments from currently more than ten to a maximum of seven chosen based on a well-defined, coherent methodology. Validation was performed on carbon black, non-pigmentary nano-scale titania, silicon/carbon composites, and lanthanum cobaltite particles, i. e., relevant materials that are commonly utilized in fuel cells, batteries, cyclohexene oxidation, catalytic combustion, photocatalysis, and heterogeneous Fenton reactions. The study showcases the potential to save time, costs, and efficiently determine HSP values in a comparable manner.     

氯铝酸离子液体酸性的吡啶探针红外光谱研究

利用吡啶探针红外光谱法研究了氯铝酸离子液体的酸性,发现当氯铝酸离子液体A lC l3的摩尔分数x为0.4~0.5时,离子液体表现出弱Lew is酸的红外特性。对吡啶探针吸附Lew is酸位A l2C l7-、A lC l4-、A l2C l6和A lC l3的各振动模式红外特征峰峰位进行了归属,通过红外特征峰峰位置和峰面积可以指示离子液体的酸强度。利用吡啶探针递增吸附法考察了吡啶递增吸附对氯铝酸离子液体酸性位的影响。研究发现,当吡啶量增加到一定程度时,Py-A l2C l7-配位络合物容易与吡啶发生反应生成Py-A lC l4-和Py-A lC l3配位络合物,从而导致离子液体的吡啶吸附红外特征峰发生变化。