Micropatterns Fabricated by Photodimerization‐Induced Diffusion

Abstract

Pattern technology plays an important role in the generation of microstructures with different functionalities and morphologies. In this report, a straightforward and versatile strategy is presented for spatially regulating the growth of a microstructure on a surface by the photodimerization of maleimide (MI). Upon exposure of ultraviolet (UV) light, photodimerization of MI in a film comprising furan‐grafted polymer and bismaleimide (BMI) produces a chemical gradient, which can drive the diffusion of BMI from the unexposed to the exposed region and from the bottom to the surface, resulting in the growth of micropatterns. Sequential crosslinking induced by the Diels–Alder reaction between MI and furan maintains the stability of pattern shape. Theoretical modeling with reaction‐diffusion equations reveal that as photodimerization moves the system far from thermodynamic equilibrium, the formation of a chemical potential gradient requires the redistribution of matter, resulting in the formation of topographies. Directional molecular motion induced by UV light can generate complex morphology, and produce materials with unique optical functions, such as charming‐ordered gratings. This straightforward method of fabricating micropatterns by photodimerization‐induced diffusion is successfully applied to patterned curved surfaces, microfluidic channels and encapsulation of integrated light emitting diode chips.

Polarization‐Dependent Ultrasensitive Dynamic Wrinkling on Floating Films Induced by Photo‐Orientation of Azopolymer

“…Herein, we report hitherto unexploited ultrasensitive dynamic wrinkling on a liquid‐supported azopolymer film via a simple illumination of linearly polarized light (LPL). The introduced light stimulus to trigger/modulate surface wrinkling has incomparable advantages (e.g., non‐contact, scalability, remote and spatiotemporal control) over other ones, [2, 21] especially in the case of freely floating films involved. Owing to the smart combination of the liquid substrate and unique photo‐responsive properties of azo‐moieties, the floating azo‐film in situ experiences a wealth of ultrafast wrinkling evolution coupled with unprecedented different polarization‐dependent wrinkling orientation conversion, i.e., from an initial polarization‐parallel orientation to the final polarization‐perpendicular one.…”

Influence of Oxidation on Structure, Performance, and Application of Metallic Glasses

“…Owing to their low surface free energy, most metallic glasses exhibit surface hydrophobicity, which is beneficial for enhancing properties such as corrosion resistance, antibacterial activity, catalytic activity, and biocompatibility. [ 74 ] Compared to thin‐film coating and surface patterning, controlled surface oxidation can be a more convenient and efficient method for adjusting surface hydrophobicity. However, the influence of surface oxidation on metallic glass hydrophobic properties remains unclear, and more work is required.…”

Photo-induced spatial gradient network for shape memory polymer with pattern-memorizing surface

“…Thermoplastic elastomer furan-grafted poly(styrene- block -butadiene- block -styrene) (SBS) was selected as the thermally responsive SMP due to its good thermal-elasticity, combined with the spatially regulated D–A crosslinking reaction by photo-induced diffusion of maleimide (MI). 45,46 The micropatterns on the SMP surface, derived from directional diffusion induced by selective photodimerization of MI, are spontaneously formed in order to stabilize the thermodynamic equilibrium of the system, rather than being artificially loaded. Thus, an SMP with a diffusion pattern is a kind of permanent shape with a steady-state.…”