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TWO-LAYER MODEL DESCRIPTION OF polymer THIN FILM DYNAMICS

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Chinese Journal of polymer Science 2013年第1期31卷 12-20页

作者： Dong-dong Peng Ran-xing Nancy Li Chi-hang Lam Ophelia K.C.Tsui Department of Physics Boston University Department of Applied Physics Hong Kong Polytechnic University

Experiments in the past two decades have shown that the glass transition temperature of polymer films can become noticeably different from that of the bulk when the film thickness is decreased below ca. 100 nm. It is broadly believed that these observations are caused by a nanometer interfacial layer with dynamics faster or slower than that of the bulk. In this paper, we examine how this idea may be realized by using a two-layer model assuming a hydrodynamic coupling between the interfacial layer and the remaining, bulk-like layer in the film. Illustrative examples will be given showing how the two-layer model is applied to the viscosity measurements of polystyrene and polymethylmethacrylate films supported by silicon oxide, where divergent thickness dependences are observed.

关键词： polymer films Glass transition Viscosity.

Photo—Induced Magnetic Anisotropy of polymer Film Containing Azobenzene Organic Free Radical Group

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Chinese Physics Letters 2003年第2期20卷 240-242页

作者：徐则达张勇等 DepartmentofpolymerScienceandEngineering CollegeofChemistryPekingUniversityBeijing100871

The forward degenerate four-wave mixing geometry was employed to induce microstructure in an organic free radical azobenzene polymer film. Before irradiated with Ar+ laser beams (λ = 514.5nm), the azobenzene organic free radical polymer exhibits magnetic isotropic measured by superconducting quantum interference device. After photo-induced microstructure, the polymer film becomes magnetic anisotropy. When the applied magnetic field H = 50 Gauss, the magnetization along the normal direction of the polymer film is Mz = 5.5×10-5emu/g, which is larger than Mx = 4.1×10-5emu/g in the direction parallel to the polymer film.

关键词： polymer films

Stimulated Emission from a TiO2 Particle-Dispersed Dye polymer Plane Waveguide

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Chinese Physics Letters 2009年第1期26卷 325-327页

作者：王琼叶莉华奚俊吕昌贵胡国华方敏崔一平 Advanced Photonics Center School of Electronic Science and Engineering Southeast University Nanjing 210096

We report the stimulated emission from a dye doped polymer plane waveguide with TiO2 particles. This waveguide consists of a poly （methylmethacrylate）（PMMA） film containing laser dye DCM as a gain medium. The emission spectrum of the film pumped by the Nd：YAG laser is different from the amplified spontaneous emission of the dye-doped film without particles. It is shown that when the excitation intensity reaches the threshold 9.6 μJ, the broad band emission spectrum narrows into multiple separate peaks with central wavelength of 608 nm. The linewidth of the sharp peak is 0.5 nm. According to our analyses, this phenomenon is due to the multiscattering of the disordered TiO2 particles inside the gain polymer film.

关键词： dyes optical polymers optical pumping optical waveguides photoluminescence polymer films refractive index spectral line breadth

Improving the Softness of BOPP films： From Laboratory Investigation to Industrial Processing

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Chinese Journal of polymer Science 2017年第9期35卷 1122-1131页

作者： ling-pu meng xiao-wei chen yuan-fei lin 李良彬 National Synchrotron Radiation Lab Key Laboratory of Soft Matter Chemistry Chinese Academy of Sciences University of Science and Technology of China Hefei 230026 China

Young＇s modulus of biaxially oriented polypropylene （BOPP） films prepared with homemade film stretcher was investigated, which can be used to indicate the softness of films. It was found that the modulus of films was decreased by about 69% as the content of polyethylene （PE） added into polypropylene （PP） reached 30%. Also, increasing draw temperature can induce lower stress level during stretching, which may lead to the formation of crystals with low orientation level and thus decreased modulus of films. Based on laboratory study, BOPP films produced on commercial line were studied by differential scanning calorimetry （DSC）, wide and small-angle X-ray scattering （WAXS, SAXS） with varying contents of PE. SAXS results show that the crystals are oriented in both machine direction （MD） and transverse direction （TD）, and the crystals are more oriented in TD than MD according to the WAXS results for all films. Also, the orientation parameter of crystal along TD increases from 0.68 to 0.83 as the contents of PE increase from 0% to 25%. Meanwhile, the modulus of films in MD declines with increase of PE contents generally, improving the film softness. Orientation of crystals is thus an effective structure parameter to adjust the film softness. The relationship of processing-structure-property is also established.

关键词： polymer films Stretching processing Processing-structure-property relationship Crystal orientation

Effects of chromophore concentration and film thickness on thermo-optic properties of electro-optic fluorinated polyimide films

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Chinese Optics Letters 2007年第12期5卷 712-714页

作者：宋洪祥吴承训 State Key Laboratory for Modification of Chemical Fibers and polymer Materials Donghua UniversityShanghai 200051

Electro-optic （EO） effect and thermo-optic （TO） effect are jointly considered on the basis of field-induced and temperature-affected perturbations of the operating point in waveguide components. TO coefficients of EO fluorinated polyimide films with side-chain azobenzene chromophore were measured by attenuated- total-reflection （ATR） technique at different temperatures with TE- and TM-polarized lights, respectively. It is found that the absolute values of TO coefficients increase with the increments of both chromophore concentration and film thickness, but the polarization dependence of TO coefficients increases with the increment of chromophore concentration and decreases with the increment of film thickness.

关键词： Azobenzene Chromophores Electrooptical effects Film thickness Light reflection Polyimides polymer films Waveguide components

polymer Coatings for Protection of Wood and Wood-Based Materials

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Advances in Chemical Engineering and Science 2016年第2期6卷 93-110页

作者： Tamara V. Sakhno Nikolay N. Barashkov Irina S. Irgibaeva S. V. Pustovit Yuriy E. Sakhno Poltava Department of Academy of Sciences of Technological Cybernetics of the Ukraine Poltava Ukraine R&D Micro-Tracers Inc. San Francisco CA USA Department of Chemistry Eurasian National University Astana Kazakhstan Institute of Information and Innovative Technologies Poltava State Agrarian Academy Poltava Ukraine Poltava Institute of Economics and Law at the University “Ukraine” Poltava Ukraine

Three major types of protective coating of wood and wood-based materials have been considered. These three types include the coatings based on carboxyl-containing water-soluble polymers which are easily cross-linked by inorganic salts or OH-containing compounds, pH-sensitive coatings and polymer multi-layer structures. First of three mentioned approaches allows affecting permeability and enhancing the prevention the loss of water from the surface of wood to its surrounding. The advantage of the second approach is its ability to vary and purposely adjust the polymer composition and the number and distribution of -COOH groups in the chain which make the originally water-soluble polymers completely insoluble. The strong feature of the third approach which includes broad use of hydrogen-bonded films produced by layer-by-layer self-assembly is the possibility of manipulation of coatings stability after construction.

关键词： Protective Coatings polymer films pH-Sensitivity Water-Soluble polymers Hydrogen Bonds Self-Assembly