Thin Films of Photoactive Polymer Blends

Photoactive polymer blends: Films consisting of two photoactive homopolymers, MEH‐PPV and P3HT, are prepared via spin coating. Investigation of the lateral domain distance inside the blended film, performed by using grazing incidence small angle X‐ray scattering techniques, shows that the theoretically predicted blending ratio seems most promising (see figure).

     

金属锌表面膜形成的椭圆偏振技术研究

介绍了近年作者课题组使用椭圆偏振技术研究金属锌表面氧化膜的形成,包括多晶锌表面自然氧化物薄膜的形成及其光学性能和电子结构、不同气氛自然氧化物膜的生长研究以及在碱性碳酸盐介质金属锌的电化学过程等方面的工作. 旨在通过原位和非原位椭圆偏振技术了解金属锌表面氧化物膜层的光、电性能以及膜层结构的改变和生长动力学,这对评估锌氧化层的总体性能有着重要意义.     

Pattern Formation in Thin Polymer Films Containing Conducting Polyaniline

Summary: In the present work knowledge the authors tried to direct the phase separation process in a thin polymer composite film to manufacture a polymer pattern via self organisation of the blend components. The Au substrate was modified by applying with a PDMS stamp a pattern of alternating stripes of a self-assembled monolayer. This in turn influenced the microstructure of the blend, allowing for the production of elongated domains repeating the pattern of the substrate. The blends studied in this work contained conducting polyaniline doped with camphorsulfonic acid or diphenyl phosphate and polystyrene. The role of the dopant was to induce electrical conductivity in polyaniline as well as to improve its solubility in common organic solvents. The microstructure of thin films was analysed using atomic force microscopy (AFM), dynamic secondary ion mass spectroscopy (dSIMS) and optical microscopy.     

Utilizing Polymer Blends to Prepare Ultrathin Films with Diverse Cellulose Textures

This paper presents an overview of the recent work on ultrathin polymer blend films containing cellulose. Three systems prepared via trimethylsilyl cellulose derivative, which is subsequently hydrolyzed to cellulose, are presented: polystyrene/cellulose, poly(methyl methacrylate)/cellulose and polystyrene-block-polyethyleneoxide/cellulose. Diverse textures emerge within the films depending on the interactions between the polymers and their interactions with the substrate as well as on different solubilities of the polymers. Furthermore, an ultrathin film containing a cellulose/xylan blend is presented. This film was deposited directly from a common solvent (dimethylacetamide/lithium chloride) and it did not exhibit distinct morphological patterns comparable to the blends with synthetic polymers.     

Electrogenerated Chemiluminescence of Pure Polymer Films and Polymer Blends

We recently reported the discovery of soliton‐like electrogenerated chemiluminescence (ECL) waves from pure conjugated polymer films and gold‐nanoparticles‐doped polymer films. In addition to a more detailed study of these polymer systems by changing the film thickness and the distribution of local leaks, we also apply the ECL wave phenomenon to polymer blends of conjugated and nonconjugated polymers. Poly(9,9‐dioctylfluorene‐co‐benzothiadiazole) (F8BT) is used as the active material that is oxidized and produces ECL with the presence of a co‐reactant, tri‐n‐propylamine (TPA). Several factors such as film thickness, artificial leaks, and solubility of doped polymers are examined for their effects on the ECL behavior. When polystyrene (PS), less soluble in the electrolyte, is blended with F8BT, dotted ECL signals are observed and transported as waves. When poly(methyl methacrylate) (PMMA), more soluble in the electrolyte, is blended with F8BT, PMMA serves as local scratches and ECL waves are triggered simultaneously from the whole film.

     

Novel Hierarchic Structures in Polymer Blends

We use computer simulations to investigate the dissolution and phase separation process in polymer blends. In particular, we take initial cylindrical and spherical structures and allow them to dissolve in the one phase region. Before the structure can completely dissolve, however, we thrust the system into the two-phase region. Phase separation then occurs such that hierarchic structures are formed both inside and outside the confines of the original structure. These novel hierarchic structures can be of significant technological importance.     

Characterization of Thin Polymer Films on the Nanometer Scale with Confocal Raman AFM

The combination of an atomic force microscope (AFM) with a Confocal Raman Microscope (CRM) has been used to study the composition of various thin films of polymer blends. The high spatial resolution of the AFM enables the morphological characterization of the polymer blends on the nanometer scale. Furthermore, when operating the AFM in Digital Pulsed Force Mode (DPFM), topographic information and local stiffness can be simultaneously recorded. This allows the material-sensitive characterization of heterogeneous materials. Thin films where PMMA (at room temperature a glassy polymer) is blended with two different styrene-butadiene rubbers are investigated. The presence of PMMA in both phase-separated thin films allows the comparison of the mechanical properties of the two different rubber phases using DPFM-AFM. When PMMA is blended with PET due to their similar mechanical properties (both are in the glassy state at room temperature) the assignment of the two phases to the corresponding polymers by AFM is rather difficult. Here, Raman spectroscopy provides additional information on the chemical composition of materials. In combination with a confocal microscope, the spatial distribution of the various phases can be determined with a resolution down to 200 nm. Therefore, the topographically different structures observed in AFM images can be associated to the chemical composition by using the Confocal Raman Microscope (CRM).     

用椭偏光谱法测量很薄固体膜的光性

本文讨论了利用棉偏光谱法测量很薄固体膜的光性的原理和方法,包括椭偏计算模型的建立、模型的合适性等问题,考察了环境介质-薄膜-衬底三根系统和环境介质-薄膜-界面过渡层-衬底四相系统,并引入了一种简化椭偏计算的方法。此外,本文也给出了两个研究实例,包括Si衬底上的Pt膜和PtSi膜。     

Transparent Polymer Opal Thin Films with Intense UV Structural Color

We report on shear-ordered polymer photonic crystals demonstrating intense structural color with a photonic bandgap at 270 nm. Our work examines this UV structural color, originating from a low refractive index contrast polymer composite system as a function of the viewing angle. We report extensive characterization of the angle-dependent nature of this color in the form of ‘scattering cones’, which showed strong reflectivity in the 275–315 nm range. The viewing range of the scattering was fully quantified for a number of planes and angles, and we additionally discuss the unique spectral anisotropy observed in these structures. Such films could serve as low-cost UV reflection coatings with applications in photovoltaics due to the fact of their non-photobleaching and robust mechanical behavior in addition to their favorable optical properties.     

高分子混合物薄膜的相分离行为

从高分子混合物薄膜的相分离行为的机理，相分离后期粗化动力微区尺寸与时间的标度关系，影响高分子混合物薄膜表面形态形成的因素等几个方面对近年来高分子混合物薄膜相行为的研究进展进行总结，概述了今后可能的发展趋势。     

Preferential Partition of Nanowires in Thin Films of Immiscible Polymer Blends

Summary: The preferential partition of silver nanowires in thin films of polystyrene/poly(vinyl pyrrolidone) (PS/PVP, with a 30/70 weight ratio) blends, that induces drastic blend morphology variation, is reported. The silver nanowires are fabricated with the anodic aluminum oxide templating method, and have a diameter of 300 nm and length of 10 µm. At a higher nanowire loading of 10 wt.‐%, the silver nanowires are entangled and selectively concentrate within the continuous PVP domain. If surface modified by thiols carrying hydrophobic tails, the silver nanowires become hydrophobic and prefer to stay within the discrete hydrophobic PS domains. At a lower nanowire loading of 5 wt.‐%, the nanowires are non‐entangled and concentrate at regions near the interfaces of the PS and PVP phases, which induces the formation of interconnected PS domains.

Preferential partition of silver nanowires in thin films of PS/PVP (30/70) blends at a casting temperature of −10 °C.     

提高聚合物共混相容性的反应性聚合物

反应性聚合物作为聚合物共混的增容剂受到越来越广泛的重视。本文论述了该类反应性聚合物的制备，分类及研究开发现状，并结合实例讨论了其增容作用效果。     

Shear‐induced Apparent Shift of Phase Boundary of Binary Polymer Blends

Summary: The combined influence of the thermodynamical and hydrodynamic effects of shear was tentatively considered for the first time, in the modeling of the shear‐induced phase behavior of binary polymer blends in this paper. In this model, the original “two‐fluid” model proposed by Onuki 1 , 2 was modified by replacing the quiescent thermodynamical term with the one defined in the frame of extended irreversible thermodynamics (EIT). 3 - 5 The stress term of the polymer blend was determined by using the mixing rule of “Double Reptation” 6 , 7 along with the Graessley's 8 functions to make the model applicable in both linear and weak non‐linear regions. Then the apparent shift of phase boundary of a model blend system was computed by using this theory. It's found that this modified theory can predict both the “miscibility gap” and anisotropical phase separation of the polymer blend, while the two different previous theories, that is the pure thermodynamical one and hydrodynamic one, could only predict one but not both of them. For example, this modified “two‐fluid” model predicts that the miscibility gap can be observable not only in vorticity direction but also in the velocity gradient direction.

The calculated reduced stored energy F_s/RT as a function of Φ_A and the temperature T (shear rate: 0.5 s⁻¹).     

聚合物共混：Ⅰ.聚合物共混物的制备方法

本讲主要介绍聚合物共混物的制备方法,其中包括熔融共混、溶液共混、胶乳共混、冷冻干燥共混、接技共聚共混、互穿聚合物网络、就地反应型共混、分子共混等.     

红外椭圆偏振光谱及其应用

阐述了红外椭圆偏振光谱的原理，技术的发展，对国外ＳＩＲＥ的应用做了介绍并给出部分实例，共收集文献２９篇。     

Dewetting and Phase Behaviors for Ultrathin Films of Polymer Blend

Summary: Dynamics of dewetting and phase separation in ultrathin films (thickness is ca. one radius of gyration, ≈1 R_g) of poly(methyl methacrylate) (PMMA) and poly(styrene‐ran‐acrylonitrile) (SAN) blends on Si substrate has been studied by in situ atomic force microscopy (AFM). In the miscible region, a “spinodal‐like” dewetting driven by a composition fluctuation recently predicted by Wensink and Jérôme (Langmuir 2002 , 18, 413) occurs. In the two‐phase region, the dewetting of the whole film is followed by phase separation in the droplets, coupling with the wetting of the substrate by the PMMA extracted by the strong attractive interaction between them.

     

Superspreading on Immersed Gel Surfaces for the Confined Synthesis of Thin Polymer Films

Liquid spreading is of significant interest in science and technology. Although surface topography engineering and liquid surface‐tension regulating can facilitate spreading, the spreading layers in these strategies are inevitably inhomogeneous or contaminated with surfactants. Herein, we show a general strategy to realize the superspreading of liquids on mutually soluble gel surfaces. The cooperation of the hydraulic pressure under liquid phase and liquid‐like property of gel surfaces can dramatically eliminate the local pinning effect and enhance the advancement of three‐phase contact line, thus forming stable and homogeneous superspreading liquid layers. Such liquid layers can be converted into various functional thin polymer films with controlled thicknesses (nm‐ to µm‐scale) through one‐step polymerization of the reactants. Our strategy offers opportunities for large‐scale synthesis of versatile functional thin films for various applications.     

Sol-Gel Preparation of α-Fe2O3 Thin Films: Structural Characterization by XAFS and Raman

Films of Fe2O3 have been prepared by two different sol-gel syntheses, starting from inorganic salts as precursors, Fe(NO3)3 · 9H2O or FeCl3 · 6H2O. Differences in the local order between the two preparations are investigated by XAFS (X-Ray Absorption Fine Structure) and Raman measurements.     

Phase Morphologies of Binary Polymer Blends Predicted by Systematically Coarse‐Grained Models

In this work, the combined iterative Boltzmann inversion/conditional reversible work scheme is extended with a little modifications to derive the systematically coarse‐grained (CG) potentials for simulating two typical atactic polymer blends composed of poly(methyl methacrylate) (PMMA) and poly(vinyl chloride) (PVC) or polystyrene (PS). Molecular dynamics simulations are extensively performed on the two blends with a wide formulation range. It is revealed by these simulations that, throughout the entire composition range, the PMMA/PVC blend is homogeneous whereas the PMMA/PS blend undergoes phase separation, which agrees well with the experimental observation that the former exhibits strong interactions that are absent in the latter. Depending upon the formulation, the immiscible PMMA/PS blend presents one single‐ or double‐continuous phase. It is further confirmed that intermolecular interactions play the key roles in forming the phase morphologies, which in turn can be inferred from only the three nonbonded CG potentials of one unlike pair and two like pairs.