Reversible Surface Patterning by Dynamic Crosslink Gradients: Controlling Buckling in 2D

Abstract

Harnessing the self-organization of soft materials to make complex, well-ordered surface patterns in a noninvasive manner is challenging. The wrinkling of thin films provides a compelling strategy to achieve this. Despite much attention, however, a simple, single-step, reversible method that gives rise to controlled, two-dimensional (2D) ordered, continuous, and discontinuous patterns has proven to be elusive. Here a novel, robust method is described to achieve this using an ultraviolet-light-sensitive anthracene-containing polymer thin film. The origin of the patterns is the local buckling of the thin film, where the control over the topology is given by laterally patterning out-of-plane gradients in the crosslink density of the film. The underlying buckling mechanics and formation of the surface features are well-described by finite element analysis. By illuminating the film with a photomask, local and long-range patterns that can be both continuous and discontinuous are able to be written. Furthermore, the patterning is fully reversible over multiple cycles. The results demonstrate a simple strategy for erasable storage of information in a surface topography that has applications in memory, anticounterfeiting, and plasmonics.

Periodic Wrinkle‐Patterned Single‐Crystalline Ferroelectric Oxide Membranes with Enhanced Piezoelectricity

“…[ 6,7 ] Wrinkles form to minimize the energy of the soft/hard bilayer heterostructure under the compressive forces originating from the strain gradient. [ 8–10 ] On the contrary, wrinkle‐patterned oxides have rarely been realized because of their inherent brittleness and poor flexibility and elasticity. Moreover, the wrinkle‐patterned ferroelectric membranes offer an ideal platform to explore strain‐correlated fundamental phenomena such as flexoelectricity, strain‐induced ferroelectric domain evolutions, and phase transitions, as well as the periodic electric potential induced functions in flexible optical and electrical devices.…”

Dynamic wrinkling pattern exhibiting tunable fluorescence for anticounterfeiting applications

“…Owing to the randomness, 3D topography, and nondeterministic process and unpredictability of the formation, wrinkling patterns caused by a surface mechanical instability [26][27][28][29][30][31][32] can realize a higher level of security in anticounterfeiting. Combining both responsive fluorescent behavior and the dynamic wrinkling pattern [33][34][35][36][37][38][39][40][41][42][43][44][45][46][47][48] into the same anticounterfeiting tag will undoubtedly enhance the information capacity and security. Owing to the complexity of the involved chemistry and material, however, it is still very challenging to fabricate surface patterns offering dynamic fluorescence and topography.…”

Light-Written Reversible 3D Fluorescence and Topography Dual-Pattern with Memory and Self-Healing Abilities

“…6 Research dimers and the microcosmic patterns or structures could be healed without ruining the patterns. Most of the cases, the surface pattern will be erased because of the chain movement which happens during the healing process [28]. However, in this system, the crack is healed without ruining the pattern, which might be ascribed to the different chemical Research mechanisms and interactions for the formation of the patterns and the healing behavior.…”

“…Although surface wrinkling is a very convenient and cost-effective strategy to generate patterns, the surfaces always buckle or wrinkle into random patterns without preferential order because of the difficulty in controlling the surface instability. Taking spatial and temporal advantages of photo-cross-linking, we recently realized the controllable release of stress across the layers to produce the well-ordered patterns of wrinkle on the photosensitive film with the aid of photomasks [28]. This light direct-writing approach provides a competitive, noncontacting, and easy-operating strategy to fabricate surface patterns [29] and will open various interesting applications.…”