Glassy Dynamics and Glass Transition in Thin Polymer Layers of PMMA Deposited on Different Substrates
Glassy Dynamics and Glass Transition in Thin Polymer Layers of PMMA Deposited on Different Substrates
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DOI：
10.1021/ma100912r
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发表时间：
2010-09-28
期刊：
影响因子：
5.5
通讯作者：
Kremer, Friedrich
中科院分区：
文献类型：
--
作者：
Erber, Michael;Tress, Martin;Kremer, Friedrich
采用可见-椭圆偏振光谱和宽带介电谱相结合的方法研究了无规聚甲基丙烯酸甲酯（PM MA）薄膜（>= 10 nm）在相同条件下退火和测量的玻璃化动力学。为了解开底层基板的可能的效果，界面相互作用系统地修改范围从强吸引力的相互作用共价键合的PM MA刷与高接枝密度和原生氧化硅（Si/SiOx）的弱和强排斥力的相互作用，实现由Au-涂覆和HMDS-处理的Si/SiOx表面，分别。下至最薄的分析PM MA层，并且独立于所应用的衬底，这两种方法在实验精度（BDS为+/- 1 K，椭圆偏振法为+/- 2 K）内提供一致的结果。由于在这些薄的聚合物层中的一维限制，玻璃态动力学没有改变。结果进行了讨论，相对于高度有争议的文献和制备条件的影响。
Spectroscopic vis-ellipsometry and broadband dielectric spectroscopy (BDS) are combined to study the glassy dynamics of thin (>= 10 nm) layers of atactic poly(methyl methacrylate) (PM MA) annealed and measured under identical conditions. In order to unravel a possible effect of the underlying substrate, the interfacial interactions are systematically modified ranging from strong attractive interactions for covalently bonded PM MA brushes with high grafting density and for native silicon oxide (Si/SiOx) to weak and strong repulsive interactions as realized by Au-coated and HMDS-treated Si/SiOx surfaces, respectively. Down to the thinnest analyzed PM MA layers and independently from the applied substrate, both methods deliver-within the experimental accuracy (+/- 1 K for BDS and +/- 2 K for ellipsometry)-a coinciding result. The glassy dynamics arc not altered due to the one-dimensional confinement in these thin polymer layers. The results are discussed with respect to the highly controversial literature and the impact of the preparative conditions.