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首页> 外文期刊>Macromolecules >CHROMOPHORE-FUNCTIONALIZED GLASSY POLYMERS WITH LARGE SECOND-ORDER NONLINEAR OPTICAL RESPONSES - TRANSIENT DYNAMICS AND LOCAL MICROSTRUCTURE OF POLY(P-HYDROXYSTYRENES) AS ASSESSED BY IN-SITU SECOND HARMONIC GENERATION TECHNIQUES
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CHROMOPHORE-FUNCTIONALIZED GLASSY POLYMERS WITH LARGE SECOND-ORDER NONLINEAR OPTICAL RESPONSES - TRANSIENT DYNAMICS AND LOCAL MICROSTRUCTURE OF POLY(P-HYDROXYSTYRENES) AS ASSESSED BY IN-SITU SECOND HARMONIC GENERATION TECHNIQUES

机译：具有大二阶非线性光学响应的​​色度函数化玻璃态聚合物-原位二次谐波生成技术评估的多态对羟基苯甲醛的瞬态动力学和局部微观结构

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Microstructural relaxation of thin films of the poled, chromophore-functionalized amorphous polymer N-(4-nitrophenyl)-(S)-prolinoxypoly(p-hydroxystyrene) has been studied by in-situ second harmonic generation (SHG) techniques. The temporal and temperature dependence of the SHG intensity decay has been analyzed as a function of poling and processing parameters within the framework of the Kohlrausch-Williams-Watts (KWW ''stretched exponential'') model. The average SHG relaxation time, tau, increases rapidly upon reduction of the applied poling field strength, with increasing poling time (physical aging), and with decreasing film temperature. The other KWW parameter, beta, which reflects the distribution of relaxation times, decreases (the distribution broadens) moderately with increases in the applied electric field strength and strongly with increases in poling time (physical aging). The observed value of beta increases (the distribution narrows) with increasing film temperature. These trends and the variation in KWW parameters yield information regarding reorientation dynamics of the tethered chromophore molecules within the polymer matrix and thus on the nature of the system subspace which is explored during relaxation. Both parameters reveal a strikingly narrower distribution of relaxation times/reduced rotational mobility versus chromophore-doped, ''guest-host'' systems and classify the present materials as Angell ''intermediate'' glasses. The temperature dependence of the second harmonic signal decay after poling field cessation can be divided into two distinct regions: (i) above T-g, where the dynamics are characteristically nonlinear and best described by the Williams-Landel-Ferry (WLF) equation; (ii) below T-g, where the behavior is linear and modeled adequately by the Arrhenius equation. Analysis of the growth of the second harmonic signal as the poling field is applied yields a similar picture; however, limiting SHG values at temperatures significantly above T-g appear to be influenced by both thermal disruption of chromophore alignment and ion conduction/space charge effects. [References: 91]
机译：通过原位二次谐波生成（SHG）技术研究了发色团官能化的带极性发色团非晶聚合物N-（4-硝基苯基）-（S）-脯氨氧基聚（对羟基苯乙烯）薄膜的微观结构弛豫。在Kohlrausch-Williams-Watts（KWW“拉伸指数”）模型的框架内，SHG强度衰减的时间和温度依赖性已作为极化和处理参数的函数进行了分析。随着施加的极化场强度的降低，极化时间（物理老化）的增加以及膜温度的降低，平均SHG弛豫时间tau迅速增加。反映松弛时间分布的另一个KWW参数beta随着施加的电场强度的增加而适度地减小（分布变宽），而随着极化时间的增加（物理老化）而强烈减小（分布变宽）。 β的观察值随着膜温度的升高而增加（分布变窄）。这些趋势和KWW参数的变化产生了有关聚合物基体内束缚的发色团分子的重新取向动力学的信息，并因此获得了在松弛过程中探索的系统子空间的性质。与掺杂发色团的“来宾-宿主”系统相比，这两个参数都显示出弛豫时间/降低的旋转迁移率的分布范围非常窄，并将本发明材料归类为Angell“中级”玻璃。极化场停止后二次谐波信号衰减的温度相关性可分为两个不同的区域：（i）T-g上方，其中动力学具有典型的非线性特性，并由Williams-Landel-Ferry（WLF）方程最佳描述; （ii）在T-g以下，其中行为是线性的，并通过Arrhenius方程进行了充分建模。在施加极化场时分析二次谐波信号的增长会产生相似的图像;但是，在显着高于T-g的温度下限制SHG值似乎受发色团排列的热破坏和离子传导/空间电荷效应的影响。 [参考：91]

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