Ganapathi Divya, Nagamanasa K Hima, Sood A K, Ganapathy Rajesh
Department of Physics, Indian Institute of Science, Bangalore, 560012, India.
Chemistry and Physics of Materials Unit, Jawaharlal Nehru Centre for Advanced Scientific Research, Jakkur, Bangalore, 560064, India.
Nat Commun. 2018 Jan 26;9(1):397. doi: 10.1038/s41467-018-02836-6.
There is mounting evidence indicating that relaxation dynamics in liquids approaching their glass transition not only become increasingly cooperative, but the relaxing regions also become more compact in shape. Of the many theories of the glass transition, only the random first-order theory-a thermodynamic framework-anticipates the surface tension of relaxing regions to play a role in deciding both their size and morphology. However, owing to the amorphous nature of the relaxing regions, even the identification of their interfaces has not been possible in experiments hitherto. Here, we devise a method to directly quantify the dynamics of amorphous-amorphous interfaces in bulk supercooled colloidal liquids. Our procedure also helped unveil a non-monotonic evolution in dynamical correlations with supercooling in bulk liquids. We measure the surface tension of the interfaces and show that it increases rapidly across the mode-coupling area fraction. Our experiments support a thermodynamic origin of the glass transition.
越来越多的证据表明，接近玻璃化转变的液体中的弛豫动力学不仅变得越来越协同，而且弛豫区域的形状也变得更加紧凑。在众多玻璃化转变理论中，只有随机一阶理论——一个热力学框架——预测弛豫区域的表面张力在决定其大小和形态方面发挥作用。然而，由于弛豫区域的非晶态性质，迄今为止在实验中甚至无法识别它们的界面。在这里，我们设计了一种方法来直接量化大块过冷胶体液体中无定形-无定形界面的动力学。我们的方法还帮助揭示了大块液体中动力学相关性随过冷度的非单调演化。我们测量了界面的表面张力，并表明它在模式耦合面积分数范围内迅速增加。我们的实验支持玻璃化转变的热力学起源。
