Instability and Soft Patterning Laboratory, Department of Chemical Engineering, Indian Institute of Technology Kharagpur , Kharagpur 721302, West Bengal, India.
Department of Chemical Engineering and Nanoscience Center, Indian Institute of Technology Kanpur , Kanpur 208016, Uttar Pradesh, India.
ACS Appl Mater Interfaces. 2017 Jun 14;9(23):19409-19416. doi: 10.1021/acsami.6b09127. Epub 2016 Nov 11.
We report a facile patterning technique capable of creating nanostructures with different feature heights (h), periodicities (λ), aspect ratios (A), and duty ratios (D), using a single grating stamp with fixed feature height h and periodicity λ. The proposed method relies on controlling the extent of debonding and morphology of the contact instability features, when a rigid patterned stamp is gradually debonded from a soft elastic film to which it was in initial conformal contact. Depending on whether the instability wavelength (λ scales with the film thickness h as λ ≈ 3h) and the periodicity of the stamp feature (λ) are commensurate or not, it is possible to obtain features along each stamp protrusion when λ ≈ λ or patterns that span several stripes of the stamp when λ > λ. In both cases, the patterns fabricated during debonding are taller than the original stamp features (h > h). We show that h can be modulated by controlling the extent of debonding as well as the shear modulus of the film (μ). Additionally, when λ > λ, progressive debonding leads to the gradual peeling of replicated features, which, in turn, allows possible tuning of the duty ratio (D) of the patterns. Finally we show that by the simultaneous modulation of A, D, and h, it becomes possible to create surfaces with controlled wettability.
我们报告了一种简便的图案化技术，该技术使用具有固定特征高度 h 和周期性 λ 的单个光栅压印模具，即可创建具有不同特征高度（h）、周期性（λ）、纵横比（A）和占空比（D）的纳米结构。该方法依赖于控制在刚性图案压印模具逐渐从与之初始共形接触的软弹性薄膜分离时，接触不稳定性特征的脱粘程度和形貌。根据不稳定性波长（λ）与薄膜厚度 h 的关系（λ≈3h）以及压印模具特征的周期性（λ）是否匹配，可以在 λ≈λ 时获得沿着每个压印模具凸起的特征，或者在 λ＞λ 时获得跨越压印模具几个条纹的图案。在这两种情况下，在脱粘过程中制造的图案都比原始压印模具特征更高（h＞h）。我们表明，通过控制脱粘程度以及薄膜的剪切模量（μ），可以调节 h。此外，当 λ＞λ 时，渐进式脱粘会导致复制特征的逐渐剥离，这反过来又允许对图案的占空比（D）进行可能的调节。最后，我们表明通过同时调节 A、D 和 h，可以创建具有可控润湿性的表面。
