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首页> 外文会议>Polymeric Materials: Science Engineering Symposia >True Nanoscopic Investigation of Polymer Cooperation Lengths on Cooling Towards the Glass Transition
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True Nanoscopic Investigation of Polymer Cooperation Lengths on Cooling Towards the Glass Transition

机译：真正纳米镜调查聚合物合作长度对玻璃过渡的冷却

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摘要

Since Adam and Gibbs, structural relaxation near the glass transition is visualized in terms of a correlated motion of polymer segments or domains, giving rise to dynamic heterogeneities. While the time scale of dynamic heterogeneities can be directly inferred from scattering experiments, the size of the cooperatively rearranging regions (typically 1-3 nm) is generally not directly obtainable and involves model assumptions. In particular, the long awaited temperature-resolved description of the cooperation length is expected to provide vital microscopic information towards the ongoing mystery of the glass transition. An unambiguous evaluation of this small length scale warrants a direct, spatially nanoscopic investigation of the glass forming dynamics, avoiding the averaging effects associated with conventional ensemble measurements. Here, we introduce a truly model-independent spatial investigation of the molecular cooperativity of polystyrene near its glass transition. Our intermolecular friction analysis yields a cooperation length that increases from the monomer scale (0.4 nm) to 37 nm clusters, when cooling from 30 K above the glass transition. The thermal sensitivity of the cooperativity follows a power-law relationship based on critical temperatures that deviate from interpretations of macroscopic experiments, bringing our nanoscopic findings more congruent with mode coupling theories.
机译：由于ADAM和GIBB，就聚合物段或域的相关运动而言，在玻璃化转变附近的结构松弛，从而产生动态异质性。虽然可以直接从散射实验中直接推断动态异质性的时间尺度，而协作重排区域（通常为1-3nm）的尺寸通常不可能可获得并且涉及模型假设。特别地，预计合作长度的至少期待的温度分辨描述将为玻璃过渡的持续神秘提供重要的显微信息。对该小长度尺度的明确评估认证对玻璃形成动态的直接，空间纳米镜，避免与传统集合测量相关的平均效果。在这里，我们介绍了一个真正独立于模型的空间调查，对其玻璃化转变附近聚苯乙烯的分子合作性。我们的分子间摩擦分析产生的配合长度从单体刻度（0.4nm）增加到37nm簇，当冷却到玻璃化转变上方的30k时。合作率的热敏灵敏度基于偏离宏观实验的解释的临界温度来遵循幂律关系，使我们的纳米镜片发现更加一致的模式耦合理论。

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