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首页> 外文期刊>Journal of Non-Crystalline Solids: A Journal Devoted to Oxide, Halide, Chalcogenide and Metallic Glasses, Amorphous Semiconductors, Non-Crystalline Films, Glass-Ceramics and Glassy Composites >Optical and broadband dielectric investigations of photochromic polymethacrylates
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Optical and broadband dielectric investigations of photochromic polymethacrylates

机译：光致变色聚甲基丙烯酸酯的光学和宽带介电研究

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The molecular dynamics and optical switching behavior (photo alignment) of novel azobenzene containing side-group (co)polymers were studied by time-resolved optical spectroscopy and broadband dielectric spectroscopy (BDS). To elucidate the effect of the molecular structure on the photochromic properties, two series of poly(methacrylates) with different aliphatic spacer units and four different concentrations of the chromophoric monomer were investigated. For both series, an inverse relation between the switching (retardation and relaxation) times and the chromophore content was found as well as a strong correlation between switching times and alignment efficiency. Dielectric spectroscopy on all materials revealed up to three relaxation processes (alpha, alpha*, delta) above the glass transition temperature that were assigned to the dynamic glass transition of the polymer backbone and the fast and slow fluctuation of the chromophores around their long and short molecular axes. In the glassy state, occasionally two Arrhenius-type relaxations were observed that were identified as local motions of the butyl side group and the chromophore in its anisotropic environment. Both materials series showed a monotonic increase in T-g and the dynamic fragility with increasing chromophore concentration, which was explained by an increasing effect of physical crosslinking provided by the increasingly dense packed side groups. (c) 2007 Elsevier B.V. All rights reserved.
机译：通过时间分辨光谱和宽带介电谱（BDS）研究了新型的含偶氮苯侧基（共）聚合物的分子动力学和光开关行为（光取向）。为了阐明分子结构对光致变色性质的影响，研究了两个具有不同脂族间隔单元和四个不同浓度发色单体的聚（甲基丙烯酸酯）系列。对于这两个系列，都发现转换（延迟和弛豫）时间与生色团含量之间呈反比关系，并且转换时间与对准效率之间也具有很强的相关性。在所有材料上的介电谱显示出在玻璃化转变温度以上最多三个弛豫过程（α，α*，δ），这三个过程与聚合物主链的动态玻璃化转变以及生色团在其长短之间的快速和缓慢波动有关分子轴。在玻璃态下，偶尔会观察到两个Arrhenius型弛豫，这些弛豫被确定为丁基侧基和发色团在其各向异性环境中的局部运动。两种材料系列均显示出T-g的单调增加以及生色团浓度的增加而引起的动态脆性，这可以通过日益密集的堆积侧基所提供的物理交联作用的增加来解释。 （c）2007 Elsevier B.V.保留所有权利。

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