Effect of Interfacial Interactions on the Glass Transition of Polymer Thin Films
Effect of Interfacial Interactions on the Glass Transition of Polymer Thin Films
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DOI：
10.1021/ma000028v
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发表时间：
2001-06
期刊：
影响因子：
5.5
通讯作者：
O. Tsui;T. Russell;C. Hawker
中科院分区：
文献类型：
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作者：
O. Tsui;T. Russell;C. Hawker
先前的研究已经证明，聚合物薄膜的Tg强烈地依赖于聚合物与底层基底之间的相互作用γs。本文研究了聚苯乙烯（PS）薄膜的玻璃化转变温度（Tg）随薄膜厚度和γs的变化关系，并利用X射线反射率测量了薄膜的热膨胀系数。发现PS在天然氧化硅上的Tg随着膜厚度的减小而减小，与其他人的结果一致。使用锚定到基底上的苯乙烯和甲基丙烯酸甲酯的无规共聚物，γs可以通过改变苯乙烯分数f来改变。在330 A的恒定PS膜厚度的情况下，随着f从1降低到0.75，Tg降低了1.20 °C。一个类似于吉布斯-汤普森模型的分析表明，表面能不是一个合适的参数来描述界面相互作用对聚合物薄膜的Tg的影响。一个相关的局部分数变化的S…
Previous studies had demonstrated that the Tg of polymer thin films is strongly dependent on the interactions, γs, between the polymer and the underlying substrate. We present a study of the glass transition temperature, Tg, in thin films of polystyrene, PS, as a function of film thickness and as a function of γs by measuring the change in the thermal expansion using X-ray reflectivity. The Tg for PS on native silicon oxide was found to decrease with decreasing film thickness, consistent with results by others. Using random copolymers of styrene and methyl methacrylate anchored to the substrate, γs could be varied by changing the styrene fraction, f. With a constant PS film thickness of 330 A, the Tg was depressed by ∼20 °C as f was decreased from 1 to 0.75. An analysis analogous to the Gibbs−Thompson model indicated that the surface energy was not a suitable parameter to use to describe the effects of interfacial interactions on the Tg of polymer thin films. An associated local fractional change in the s...