A cationic surfactant containing a spiropyran unit is prepared exhibiting a dual‐responsive adjustability of its surface‐active characteristics. The switching mechanism of the system relies on the reversible conversion of the non‐ionic spiropyran (SP) to a zwitterionic merocyanine (MC) and can be controlled by adjusting the pH value and via light, resulting in a pH‐dependent photoactivity: While the compound possesses a pronounced difference in surface activity between both forms under acidic conditions, this behavior is suppressed at a neutral pH level. The underlying switching processes are investigated in detail, and a thermodynamic explanation based on a combination of theoretical and experimental results is provided. This complex stimuli‐responsive behavior enables remote‐control of colloidal systems. To demonstrate its applicability, the surfactant is utilized for the pH‐dependent manipulation of oil‐in‐water emulsions.

The addition of small amounts of xanthate can turn conventional RAFT polymerizations into rapid photo-activated reactions with high livingness, oxygen tolerance and versatility enabling straightforward multiblock synthesis or well plate screening.

We present a PDMS-based stamp featuring xanthates within its framework, to graft polymer brushes from its surface. The stamp demonstrates a high efficacy of polymer-supported μCP, but does not show leakage of oligomeric PDMS, which represents a common source of contamination in soft lithography.

Their inherent directional information renders patchy particles interesting building blocks for advanced applications in materials science. In this study, a feasible method to fabricate patchy silicon dioxide microspheres is demonstrated, which they are able to equip with tailor‐made polymeric materials as patches. Their fabrication method relies on a solid‐state supported microcontact printing (µCP) routine optimized for the transfer of functional groups to capillary‐active substrates, which is used to introduce amino functionalities as patches to a monolayer of particles. Acting as anchor groups for polymerization, photo‐iniferter reversible addition‐fragmentation chain‐transfer (RAFT) is used to graft polymer from the patch areas. Accordingly, particles with poly(N‐acryloyl morpholine), poly(N‐isopropyl acrylamide), and poly(n‐butyl acrylate) are prepared as representative acrylic acid‐derived functional patch materials. To facilitate their handling in water, a passivation strategy of the particles for aqueous systems is introduced. The protocol introduced here, therefore, promises a vast degree of freedom in engineering the surface properties of highly functional patchy particles. This feature is unmatched by other techniques to fabricate anisotropic colloids. The method, thus, can be considered a platform technology, culminating in the fabrication of particles that possess locally precisely formed patches on particles at a low µm scale with a high material functionality.

Microcontact printing (μCP) is a versatile and low-cost technique for surface patterning, allowing for the fabrication of intricate designs with relative ease.

Owing to their property to alter their surface‐activity upon the irradiation with light, photoswitchable surfactants have gained tremendous interest in colloidal science. Their mere addition to a colloidal system allows, e. g., to obtain control over polyelectrolytes, micro‐ and nanoscale particles or emulsions. Most literature examples focus on azobenzene‐based, or related, systems, which employ a photoisomerization reaction for switching. Other structures, such as spiropyrans, play a subordinate role, although they have gained increasing attention over the past few years. In this perspective article, we want to provide an overview about existing systems of photoswitchable surfactants. We address the issue that alternative photoswitches are given less attention, and what benefits surfactants could possess that are based on said switchable units. With our contribution, we want to broaden the view on stimuli‐responsive surfactants – and to provide a guideline for the design of novel structures.