期刊
PHYSICAL REVIEW LETTERS
卷 107, 期 23, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevLett.107.235701
关键词
-
We study the glass transition in confined polymer films and present the first experimental evidence indicating that two separate mechanisms can act simultaneously on the film to propagate enhanced mobility from the free surface into the material. Using transmission ellipsometry, we have measured the thermal expansion of ultrathin, high molecular- weight ( MW), freestanding polystyrene films over an extended temperature range. For two different MWs, we observed two distinct reduced glass transition temperatures (T-g's), separated by up to 60 K, within single films with thicknesses h less than 70 nm. The lower transition follows the expected MW dependent, linear T-g(h) behavior previously seen in high MW freestanding films. We also observe a much stronger upper transition with no MW dependence that exhibits the same T-g(h) dependence as supported and low MW freestanding polymer films.
作者
我是这篇论文的作者
点击您的名字以认领此论文并将其添加到您的个人资料中。
推荐
暂无数据