Design of Active Interfaces Using Responsive Molecular Components

Abstract

Responsive interfaces are interfaces that show a defined and reversible change in physical properties in response to external stimuli. Typically, responsive interfaces result from the immobilization of responsive molecular components at the interface that translate a nanoscale signal into a macroscopic effect. Responsive interfaces can also be obtained if the topology of the interface can be reversibly changed using an external stimulus. As the surface of any material is its connection to the environment, responsive interfaces provide opportunities for interactive materials which are not only able to change properties upon demand, but also sense their environment and act autonomously. The application of responsive molecular components at interfaces, however, requires chemical and physical compatibility with the material surface of interest, posing a challenge not least in the retention of the responsive functionality. The state of the art in "active" interfaces which display responsive wettability, permeability, or adhesion is discussed, with a particular emphasis on microscale and nanoscale patterning since patterned interfaces can give rise to unique material properties. Finally, perspectives in the development of responsive interfaces, as well as promising approaches for bypassing the most prominent challenges are discussed.

Hydrogel Patterning with Catechol Enables Networked Electron Flow

“…The resulting film is soft, flexible, and transparent, and made from components that can reasonably be expected to be biologically compatible (e.g., for direct contact with skin or food), degradable, and possibly even ingestible. [ 66–70 ]…”

Acid-catalysed liquid-to-solid transitioning of arylazoisoxazole photoswitches

“…Over the past decades, molecular switches have become ubiquitous in the development of smart materials, rendering reversible changes in material function upon input stimuli. 1,2 In addition to designing new molecular switches and the synthetic optimization of existing structures, the deeper understanding of their fundamental responsivity has led to a vast body of research on small molecular photoswitches, most notably on azobenzenes, 3,4 spiropyrans 5,6 and diarylethenes. 7 These exemplar molecular photoswitches have proven to be excellent building blocks for integration in materials owing in particular to their multi-responsiveness, reacting not only to light, 8,9 but also, e.g., heat, 10 mechanical input, 11 and pH-changes.…”

How the Shape and Chemistry of Molecular Penetrants Control Responsive Hydrogel Permeability

“…g ., temperature or pressure). 2 , 4 , 5 They have become building blocks in a broad repertoire of biomedical, pharmaceutical, and other applications, including chemical separation, 6 biosensors, 7 nanofiltration, 8 , 9 active interfaces, 10 biomedical devices, 11 , 12 nanocatalysis, 13 − 16 and—maybe the most eminent example—controlled drug delivery. 3 , 17 , 18 In the latter, hydrogels can be designed to selectively encapsulate and release particular types of pharmaceuticals in a controllable way.…”