Thin films of polymer coatings have important industrial applications ranging from paints and coatings to pharmaceuticals. In many applications, the coatings are obtained by applying thin films of dilute polymer solutions, wherein the solvent evaporates to leave behind a thin polymer film. In some cases, the thin films may crack due to shrinkage stresses developed during drying. While a number of studies have focused on the stress development, the phenomenon of cracking in polymer films is not fully investigated. In the present work, thin films of a silicone polymer solution were cast on substrates of varying Young's moduli and investigated for cracking as a function of film thickness and substrate modulus. Micro-Raman spectroscopy measurements show that thin films dry uniformly while thick films form a skin at the top surface leading to slow drying rates. Transverse stresses were measured using the cantilever technique and related to the extent of cracking in the film. We investigated the influence of substrate rigidity on the cracking behavior and found that decreasing the stiffness of the substrate increases the extent of cracking.

中文翻译：

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聚合物溶液干燥膜破裂

聚合物涂料的薄膜具有重要的工业应用，范围从涂料，涂料到药品。在许多应用中，通过施加稀聚合物溶液的薄膜来获得涂层，其中溶剂蒸发而留下聚合物薄膜。在某些情况下，由于干燥过程中产生的收缩应力，薄膜可能会破裂。尽管许多研究集中在应力发展上，但尚未充分研究聚合物膜破裂的现象。在目前的工作中，将有机硅聚合物溶液的薄膜浇铸在杨氏模量不同的基材上，并研究其破裂与膜厚和基材模量的关系。显微拉曼光谱测量表明，薄膜均匀干燥，而厚膜在顶表面形成皮肤，导致干燥速度缓慢。使用悬臂技术测量横向应力，该横向应力与薄膜的破裂程度有关。我们研究了基材刚度对开裂行为的影响，发现降低基材的刚度会增加开裂程度。