Sub‐Micrometer Structure Formation during Spin Coating Revealed by Time‐Resolved In Situ Laser and X‐Ray Scattering
Sub‐Micrometer Structure Formation during Spin Coating Revealed by Time‐Resolved In Situ Laser and X‐Ray Scattering
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DOI：
10.1002/adfm.201702516
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发表时间：
2017-12
影响因子：
19
通讯作者：
Jacobus J. van Franeker;D. Hermida-Merino;C. Gommes;K. Arapov;J. Michels;René A. J. Janssen;G. Portale
中科院分区：
文献类型：
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作者：
Jacobus J. van Franeker;D. Hermida-Merino;C. Gommes;K. Arapov;J. Michels;René A. J. Janssen;G. Portale
溶液处理的聚合物薄膜有许多应用，如有机电子和嵌段共聚物纳米制造。这些薄膜通常是由自旋镀膜制成的，溶液中含有一种或多种固体，可以显示不同的相分离结构。本文通过对聚苯乙烯（PS）和富勒烯衍生物（[6,6]-苯基- C71 -丁酸甲酯，[70]PCBM）进行加工，研究了液滴状形态的形成机理。通过透射电子显微镜和掠射小角X射线散射（GISAXS）测定，最终结构由[70]PCBM液滴部分嵌入富PS基质组成，其域间距离为100-1000 nm。为了实时阐明这些形态的形成，在自旋涂层过程中进行了超快原位GISAXS耦合激光干涉测量和激光散射。原位厚度测量和激光散射表明，液-液相分离发生在≈70 vol%的溶剂。随后，仅在100-400毫秒内，几乎干燥的[70]PCBM结构域开始从膨胀的富PS基质中突出。这些结果用于验证用Flory-Huggins理论计算的三元相图。所讨论的多技术方法可以应用于研究软物质的基本方面，如在很短的时间尺度上发生的薄膜相分离。
Solution‐processed thin polymer films have many applications, such as organic electronics and block‐copolymer nanofabrication. These films are often made by spin coating a solution that contains one or more solids and can show different phase‐separated structures. The formation mechanism of the droplet‐like morphology is studied here by processing polystyrene (PS) and a fullerene derivative ([6,6]‐phenyl‐C71‐butyric acid methyl ester, [70]PCBM) from o‐xylene. The final structure consists of [70]PCBM droplets partially embedded in a PS‐rich matrix showing interdomain distance of 100–1000 nm as determined from transmission electron microscopy and grazing incidence small angle X‐ray scattering (GISAXS). To elucidate the formation of these morphologies in real time, ultrafast in situ GISAXS coupled with laser interferometry and laser scattering is performed during spin coating. In situ thickness measurements and laser scattering show that liquid–liquid phase separation occurs at ≈70 vol% solvent. Subsequently, in only 100–400 ms, almost dry [70]PCBM domains start to protrude from the swollen PS‐rich matrix. These results are used to verify the ternary phase diagram calculated using Flory–Huggins theory. The discussed multitechnique approach can be applied to study fundamental aspects in soft matter such as phase separation in thin films occurring at very short time scales.