Hierarchical 3D Patterns with Dynamic Wrinkles Produced by a Photocontrolled Diels–Alder Reaction on the Surface

Abstract

Three‐dimensional (3D) reconfigurable patterns with dynamic morphologies enable the on‐demand control of surface properties, such as optical, wetting, and adhesive properties, to achieve smart surfaces. Here, a simple yet general strategy is developed for fabricating 3D patterns with reversible wrinkles on the surface, in which a Diels–Alder (D‐A) reaction in the top layer, which consists of a reversible cross‐linked polymer network composed of a furan‐containing copolymer (PSFB) and bismaleimide (BMI), can be spatially controlled by the photodimerization of BMI. When a photomask is used during irradiation with ultraviolet (UV) light, selective photodimerization of the maleimide leads to the diffusion of maleimide from the unexposed region to the exposed region, resulting in the generation of a diffused relief pattern. By controlling the reversible D‐A reaction at different temperatures, orthogonal wrinkles can be sequentially and reversibly generated or erased in both the exposed and unexposed regions on the surface. Theoretical modeling with boundary effects reveals that the orientation of the wrinkle in the exposed region is perpendicular to the boundary, whereas the wrinkle in the unexposed region is parallel to the boundary. This strategy, based on a photocontrolled D‐A reaction, provides an important and robust alternative for fabricating 3D patterned surfaces with dynamic topographies.

Photo‐Polymerization Induced Hierarchical Pattern via Self‐Wrinkling

“…The morphology of the wrinkles is parallel to each other and perpendicular to the unexposed regions (marked as II), which might be resulted from boundary effect. [48] After the second UV irradiation without mask, labyrinth patterns formed in the region II with a much smaller wavelength (λ) of 35 µm and bigger amplitude (A) of 2.8 µm (Figure 3c,d) comparing with the patterns in region I. It might be ascribed to the boundary effect of the region I.…”

Bioinspired Multiscale Wrinkling Patterns on Curved Substrates: An Overview

“…Beyond the wrinkling of large-size uniform film bonded on elastic substrate, recently, a series of studies have revealed differently post-wrinkle morphologies in systems composed of patterned stiff films on soft substrates [111][112][113][114][115][116][117][118][119]. When the length scale of the pattern is comparable to the wavelength of wrinkles, stress localization near the pattern arises under compression.…”

“…The feature size, geometry, and spacing are all demonstrated to have important effect on the wrinkling and post-wrinkle morphologies of patterned films [ 111 , 114 , 116 , 118 ]. For example, the preformed pattern can act as novel boundary to direct surface wrinkling for controllable fabrication of hierarchical wrinkling patterns with precise orientation [ 113 , 119 ]. Besides, stress localization near the patterned region triggers the decrease of the threshold compression for the onset of various wrinkling morphologies.…”

Transparency Change Mechanochromism Based on a Robust PDMS‐Hydrogel Bilayer Structure

“…[23,30] Surface wrinkling is ubiquitous in our daily life. [31][32][33][34][35] In nature, dried fruits, leaves, and aged skins present wrinkling surfaces in response to internal/external changes. [36,37] Inspired by the distinct functions and mechanisms of biological wrinkle structures, a lot of experimental and theoretical studies have been conducted to understand and modulate various wrinkle patterns induced by thermal, mechanical, optical, or chemical stimuli on artificial materials.…”