Formation of Hierarchically Structured Thin Films

Abstract

Here, we report the preparation of hierarchically structured polymer brushes with well‐defined geometries via multiple step microcontact printing (MS‐µCP) of inks containing different ratios of initiator‐terminated thiols and non‐reactive alkylthiols. Thick (and dense), polymer brushes grew from self‐assembled monolayers (SAMs) with high concentration of initiator‐terminated thiols, and these brushes exhibited high chemical etch‐resistance, compared to thin (and less dense), brushes grown from more dilute initiator‐terminated SAMs. Upon etching, patterned crosslinking polymer brush films decorated with thin layers of Au, could be lifted off the surface to form geometrically well‐defined free‐standing hierarchical films. These polymer brush films showed interesting buckling instabilities when compressed. Areas with different brush thicknesses and Au backing showed markedly different buckling behavior, leading to unusual patterns of wrinkles with different wavelengths and orientations toward the force field.

Liquid‐Mediated Three‐Dimensional Scanning Probe Nanosculpting

“…More recently, there is rapid increasing interest in the mimicking of complex 3D structures, compared with the fabrication of conventional 2D arrays 1–4. These artificial 3D structures, in which the physical topography as well as the chemical and biological functionalities is highly‐defined, are considered promising to achieve new optical, electrical, chemical, and biological properties that the 2D arrays cannot provide 5–15…”

Effect of Er concentration on surface and optical properties of K doped ZnO sol–gel thin films

“…These wrinkle patterns, although have a certain dominant wavelength associated with them, often exhibit isotropic wave patterns. (ii) The rigid coating buckles which yield distinct wrinkling patterns ranging from homogeneous to hierarchical wrinkles [36], (iii) fiber like streaks or wrinkles could be induced by shortness of OH and OR groups during the annealing process [37]. In our previous work, we have reported the wrinkle structure formation in the Al and N codoped ZnO films prepared by sol-gel method [38].…”

Spontaneous growth of self-relief wrinkles in freely floating lipid-based nanomembranes, formed on a reactive bath of polyoxometalate aqueous solution

“…As far and deep as we could go through the literature, buckling instabilities and wrinkling were exclusively induced in these freely floating systems by externally applied stresses: lateral compressive/tensile force, capillary tension of a deposited drop, etc. [12,[19][20][21][22]. One obvious reason to this is the relaxing nature of liquids which strongly impedes the accumulation of stress at (liquid/film) interface, and thus the growth of wrinkles.…”

“…Besides the potential that the approach constitutes as a nano-fabrication tool, the genesis of self-relief wrinkles which spontaneously occur during the growth of freely floating membranes represents, as such, a major result of this work. Indeed, whereas buckling instabilities and wrinkles have obvious drastic impact 1 for systems requiring mechanical and dimensional stability, these wrinkles can also be usefully tuned to create functional patterns and structures, or used through simple scaling relations to characterize the physical properties of thin viscoelastic films [10,[12][13][14][15][16]. Although a significant understanding of these phenomena has been achieved through recent developments [14,16], there are still open issues in this field, among which the spontaneous buckling and wrinkling of freely floating films formed on liquid foundations (Langmuir type films).…”

“…For water-insoluble molecules, there are fabrication methods based on the crosslinking of Langmuir films, and the layer-by-layer (LbL) deposition followed by a lifting off step, which have produced free standing membranes of both organic and composite materials [1,[9][10][11][12]. But because of the limitation of LbL technique to oppositely charged molecules, and the multiple-step process requiring substrate removal to collect the membrane (lifting off), this method is time-consuming and of limited applications.…”