聚合物表面多级褶皱结构的屈曲机理及可控成形工艺

聚合物表面多级褶皱结构（特征为0.5-500微米）具有高表面积、高柔性和高延展性，在柔性电子和超疏水等器件上具有巨大的应用前景。现有牺牲层法和共形薄膜法等多级褶皱工艺加工效率低、褶皱形状不可控；现有理论未考虑褶皱耦合演化规律，难以精确指导工艺调控。.本项目提出单次加载-多次涂覆-多次释放方法，提高加工效率高；采用非等轴加载和释放，控制薄膜在不同方向上先后屈曲，结合薄膜沉积控制，实现褶皱逐级精确调控。项目围绕非等轴应变下褶皱再屈曲及褶皱耦合机理的关键问题，研究一级和二级褶皱非线性演化，开展非等轴应变下褶皱再屈曲行为力学建模，精确描述褶皱再屈曲的临界失稳条件；建立多级褶皱分级成形工艺过程模型，揭示多褶皱屈曲变形耦合机制，提出多级褶皱非等轴分级成形的调控原理;搭建实验平台，开展工艺实验，验证理论模型的准确性和工艺方法的可行性，为面向柔性电子和超疏水等器件的复杂多级褶皱可控成形提供理论与技术支撑。

Hierarchical wrinkled structures on the polymer surface with a feature size of 0.5 to 500 um have a high surface area, high flexibility, and high stretchability and have broad application prospects in flexible electronic and superhydrophobic devices. Existing manufacturing methods, such as the sequential wrinkling process, are of low precision control. Moreover, the traditional theory without consideration of the coupling behavior between hierarchical wrinkles is not suitable for guiding the microforming process of Hierarchical wrinkles. In this project, a multi-stage control process with a non-isoaxial stretching, multiple film coatings, and multiple strain releases is proposed to fabricate hierarchical wrinkles, where each cycle can be accurately controlled for the film thickness and the strain release in different directions. To address the key issues of the re-buckling of the film on polymers and coupling mechanisms between hierarchical wrinkles, first, the deformation behavior of single-layer wrinkles and two-layers wrinkles is studied. Then, the re-buckling mechanics of the thin film under non-isoaxial strain is modeled to accurately predict the critical instability conditions for the re-buckling. After that, the multi-stage forming process for hierarchical wrinkles is numerically analyzed, and the coupling mechanism of hierarchical wrinkles is revealed. Moreover, the geometry of hierarchical wrinkles as a function of strain release history and film deposition history is analyzed, and then a sophisticated control strategy of the multi-stage forming process for hierarchical wrinkles is established. Eventually, the multi-stage forming process prototype is built to verify the feasibility of the proposed process method and the accuracy of the theoretical model, to provide theoretical and technical support for the high-precision manufacture of hierarchical wrinkled structures on polymer sufaces.