Surface Fluctuations Dominate the Slow Glassy Dynamics of Polymer-Grafted Colloid Assemblies,ACS Central Science

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Surface Fluctuations Dominate the Slow Glassy Dynamics of Polymer-Grafted Colloid Assemblies
ACS Central Science ( IF 12.7 ) Pub Date : 2018-08-27 00:00:00 , DOI: 10.1021/acscentsci.8b00352
Makoto Asai ₁ , Angelo Cacciuto ₂ , Sanat K Kumar ₁

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Colloids grafted with a corona layer of polymers show glassy behavior that covers a wide range of fragilities, with this behavior being tunable through variations in grafting density and grafting chain length. We find that the corona roughness, which is maximized for long chain lengths and sparse grafting, is directly correlated to the concentration-dependence of the system relaxation time (fragility). Relatively rougher colloids result in stronger liquids because their rotational motions become orientationally correlated across the whole system even at low particle loadings leading to an essentially Arrhenius-like concentration-dependence of the relaxation times near the glass transition. The smoother colloids do not show as much orientational correlation except at higher densities leading to fragile behavior. We therefore propose that these materials are an ideal model to study the physical properties of the glass transition.

中文翻译：

表面波动主导聚合物接枝胶体组件的慢玻璃态动力学

接枝有聚合物电晕层的胶体表现出玻璃态行为，涵盖了广泛的脆性，这种行为可以通过接枝密度和接枝链长度的变化来调节。我们发现，长链长度和稀疏接枝时最大的电晕粗糙度与系统弛豫时间（脆性）的浓度依赖性直接相关。相对较粗糙的胶体会产生更强的液体，因为即使在低颗粒负载下，它们的旋转运动在整个系统中也具有方向相关性，从而导致玻璃化转变附近的弛豫时间基本上呈阿伦尼乌斯式浓度依赖性。更光滑的胶体不会表现出那么多的取向相关性，除非密度较高，导致脆弱的行为。因此，我们认为这些材料是研究玻璃化转变物理性质的理想模型。

更新日期：2018-08-27

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