Nanoscale compositional heterogeneity in block copolymers can impart synergistic property combinations, such as stiffness and toughness. However, until now, there has been no experimental method to locally probe the dynamics at a specific location within these structured materials. Here, this was achieved by incorporating pyrene-bearing monomers at specific locations along the polymer chain, allowing the labeled monomers’ local environment to be interrogated via fluorescence. In lamellar-forming poly(butyl methacrylate-b-methyl methacrylate) diblock copolymers, a strong gradient in glass transition temperature, T_g, of the higher-T_g block, 42 K over 4 nm, was mapped with nanometer resolution. These measurements also revealed a strongly asymmetric influence of the domain interface on T_g, with a much smaller dynamic gradient being observed for the lower-T_g block.

中文翻译：

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以纳米分辨率直接测量自组装共聚物中的局部玻璃化转变

嵌段共聚物中的纳米级组成异质性可以赋予协同作用，例如刚度和韧性。但是，到目前为止，还没有实验方法可以在这些结构化材料内的特定位置局部探测动力学。在这里，这是通过在聚合物链的特定位置掺入含pyr单体来实现的，从而可以通过荧光询问标记的单体的局部环境。在层状形成的聚（甲基丙烯酸丁酯-b-甲基丙烯酸甲酯）二嵌段共聚物中，玻璃化转变温度T _g与较高的T _g有很强的梯度关系。以4纳米分辨率绘制了4 K上42 K的图块。这些测量结果还揭示了畴界面对T _g的强烈不对称影响，对于较低T _g的嵌段观察到的动态梯度小得多。