Molecular weight dependence of reductions in the glass transition temperature of thin, freely standing polymer films
Molecular weight dependence of reductions in the glass transition temperature of thin, freely standing polymer films
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DOI：
10.1103/physreve.63.031801
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发表时间：
2001-03-01
影响因子：
2.4
通讯作者：
Dutcher, JR
中科院分区：
文献类型：
--
作者：
Dalnoki-Veress, K;Forrest, JA;Dutcher, JR
我们已经使用透射椭圆偏振法进行全面的研究自由站立的聚苯乙烯薄膜的玻璃化转变温度Tg。研究中使用了6种分子量（M）/bar（w），范围为575 × 10（3）至9100 × 10（3）。对于每个（M）/bar（w）值，随着膜厚度h的减小，观察到T-g的大幅度降低（比本体值低80 ℃）。我们详细地研究了在链约束效应占主导地位的区域中，T-g约化对（M）和巴（w）的依赖关系。提出的实证分析是高度暗示的流动性在薄的自由站立的膜，在散装和不同的通常的合作运动与玻璃化转变被抑制的机制的存在。
We have used transmission ellipsometry to perform a comprehensive study of the glass transition temperature T-g of freely standing polystyrene films. Six molecular weights (M) over bar (w), ranging from 575 X 10(3) to 9100 X 10(3), were used in the study. For each (M) over bar (w), value, large reductions in T-g (as much as 80 degreesC below the bulk value) were observed as the film thickness h was decreased. We have studied in detail the dependence of the T-g reductions on (M) over bar (w) in a regime dominated by chain confinement effects. The empirical analysis presented is highly suggestive of the existence of a mechanism of mobility in thin freely standing films that is inhibited in the bulk and distinct from the usual cooperative motion associated with the glass transition.