The interplay of thermodynamics and kinetics: imparting hierarchical control over film formation of self-stratified blends
The interplay of thermodynamics and kinetics: imparting hierarchical control over film formation of self-stratified blends
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热力学和动力学的相互作用：对自分层共混物的成膜进行分级控制
DOI：
10.1039/c9sm01147a
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发表时间：
2020
期刊：
影响因子：
3.4
通讯作者：
Dadmun, Mark D.
中科院分区：
文献类型：
--
作者：
Rinehart, Samantha J.;Yuan, Guangcui;Dadmun, Mark D.
旋涂法已成为一种有吸引力的方法来制造聚合物薄膜，用于有机电子器件，如场效应晶体管和发光二极管。许多研究表明，改变旋转浇铸参数可以提高器件性能，这与聚合物排列程度、结晶度和薄膜形态直接相关。为了提供一个彻底的理解的平衡的热力学和动力学因素，影响分层的聚合物共混物薄膜，我们监测分层的聚合物共混物薄膜开发的聚（3-己基噻吩-2，5-二基）和聚（甲基丙烯酸甲酯）共混物在控制的加载比，相对分子量，和铸造速度。这些薄膜的结构，其特征在于通过中子反射率，结果表明，在最快的铸造速度，聚合物-聚合物的相互作用和表面能的聚合物的共混物决定最终的膜结构，并在最慢的铸造速度，有较少的控制膜分层由于聚合物-聚合物的相互作用，表面能，和熵同时驱动分层。同样，聚合物在预沉积溶液中的相对溶解度极限在最低浇铸速度下的分层过程中起作用。这些结果拓宽了目前对聚合物共混物薄膜中的旋转浇铸条件和垂直相分离之间的关系的理解，并为聚合物薄膜制造工艺的改进合理设计提供了基础，以实现目标分层，从而提高性能。
Spin casting has become an attractive method to fabricate polymer thin films found in organic electronic devices such as field-effect transistors, and light emitting diodes. Many studies have shown that altering spin casting parameters can improve device performance, which has been directly correlated to the degree of polymer alignment, crystallinity, and morphology of the thin film. To provide a thorough understanding of the balance of thermodynamic and kinetic factors that influence the stratification of polymer blend thin films, we monitor stratified polymer blend thin films developed from poly(3-hexylthiophene-2,5-diyl) and poly(methyl methacrylate) blends at controlled loading ratios, relative molecular weights, and casting speed. The structures of these thin films were characterized via neutron reflectivity, and the results show that at the fastest casting speed, polymer–polymer interactions and surface energy of the polymers in the blend dictate the final film structure, and at the slowest casting speed, there is less control over the film layering due to the polymer–polymer interactions, surface energy, and entropy simultaneously driving stratification. As well, the relative solubility limits of the polymers in the pre-deposition solution play a role in the stratification process at the slowest casting speed. These results broaden the current understanding of the relationship between spin casting conditions and vertical phase separation in polymer blend thin films and provide a foundation for improved rational design of polymer thin film fabrication processes to attain targeted stratification, and thus performance.