期刊
PHYSICAL REVIEW E
卷 79, 期 1, 页码 -出版社
AMER PHYSICAL SOC
DOI: 10.1103/PhysRevE.79.011801
关键词
adsorbed layers; aluminium; annealing; contact angle; dielectric relaxation; electrodes; glass transition; polymer films; thin films
资金
- BAM
The dynamic glass transition (alpha relaxation, structural relaxation) of ultrathin polysulfone films prepared between aluminum electrodes is investigated by dielectric relaxation spectroscopy. As a main result, it is found that the glass transition temperature T-g does not depend on the thickness of the polymeric layer down to a thickness of 10 nm. For thicknesses lower than 10 nm, an increase of T-g is observed. A more detailed analysis of the temperature dependence of the relaxation rates reveals that the Vogel temperature increases and the fragility decreases systematically with decreasing film thickness d. Further, the dielectric strength Delta epsilon decreases with decreasing d. This is discussed by the formation of a surface layer of adsorbed polysulfone segments having a reduced molecular mobility with regard to the time scale characteristic of the glassy dynamics of bulk polysulfone. Plotted versus inverse film thickness Delta epsilon decreases linearly with 1/d and becomes zero for an extrapolated length scale of 10 nm. From that it is concluded that the thickness of the adsorbed boundary layer is about 5 nm. Contact-angle measurements were carried out to confirm the strong interaction between aluminum and polysulfone. It is also shown that preparation details like annealing conditions strongly influence the glass transition of supported ultrathin 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