Reversible negative thermal expansion of polymer films.
Reversible negative thermal expansion of polymer films.
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DOI：
10.1103/physreve.66.061801
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发表时间：
2002-12
期刊：
影响因子：
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通讯作者：
M. Mukherjee;M. Bhattacharya;M. Sanyal;T. Geue;J. Grenzer;U. Pietsch
中科院分区：
文献类型：
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作者：
M. Mukherjee;M. Bhattacharya;M. Sanyal;T. Geue;J. Grenzer;U. Pietsch
对聚合物薄膜特性的基本了解对于开发纳米技术的应用至关重要。聚合物薄膜的能量和角色散 X 射线反射率测量结果作为温度的函数，在低于玻璃化转变温度 T(g) 时表现出可逆的负热膨胀。高于 T(g) 时，厚度膨胀变得几乎等于预期的体积膨胀。这些结果可以根据界面温度、链缠结和相关熵变化的无序演化来解释。
A basic understanding of the properties of thin polymer films is of fundamental importance for developing applications in nanotechnology. Results of energy and angle dispersive x-ray reflectivity measurements on polymer thin films as a function of temperature exhibit reversible negative thermal expansion below the glass transition temperature T(g). Above T(g), the thickness expansion becomes almost equal to the expected bulk volume expansion. These results could be explained on the basis of evolution of disorder with temperature at the interfaces, chain entanglement and associated entropy changes.