Study on the water-induced deformation of wrinkle patterns in thin films

2022 Fiscal Year Final Research Report

• Project/Area Number: 19K14843
• Research Category: Grant-in-Aid for Early-Career Scientists
• Allocation Type: Multi-year Fund
• Review Section: Basic Section 18010:Mechanics of materials and materials-related
• Research Institution: Nagoya University (2021-2022); Osaka University (2019-2020)
• Principal Investigator: Nagashima So 名古屋大学, 工学研究科, 准教授 (80800317)
• Project Period (FY): 2019-04-01 – 2023-03-31
• Keywords: リンクル / 薄膜 / 表面不安定現象 / 水滴 / 表面張力

Outline of Final Research Achievements

Spontaneous formation of wrinkle patterns in compressed thin films has attarcted much attention. Recently, we have uncovered a phenomenon in which wrinkles transition into folds when a water droplet comes in contact with the wrinkles. However, the underlying mechanism remains to be elucidated. In this study, through in-situ microscope observations, we have revealed that the capillary forces of water help to increase the local compressive strains, which causes the water-induced wrinkle-to-fold transitions to occur. Furthermore, we have shown that the transitions can be induced only when the film is sufficiently thin and superhydrophilic. The characteristic dimensions of the resulting folds vary according to the film thickness. The water-induced wrinkle-to-fold transition offers a simple method for developing folds at designated locations on a wrinkled surface formed under small biaxial compression, which is difficult to achieve with conventional approaches.

Free Research Field

固体力学

Academic Significance and Societal Importance of the Research Achievements

本研究成果は，水という普遍物質を活用した新たなナノ加工技術の開発に結びつくものである。安全性と利便性に優れ，単一面内におけるリンクルとフォールドの共存を可能にする。機能特性の複合化・高度化をもたらすため，従来の方法論では実現困難な機能表面の創製，機能デバイスの開発ならびに新規研究分野の開拓に繋がる。以上の点において，学術的意義および社会的意義を有する。