Miniaturization and parallelization of combinatorial organic synthesis is important to accelerate the process of drug discovery while reducing the consumption of reagents and solvents. This work presents a miniaturized platform for on‐chip solid‐phase combinatorial library synthesis with UV‐triggered on‐chip cell screening. The platform is based on a nanoporous polymer coating on a glass slide, which is modified via photolithography to yield arrays of hydrophilic (HL) spots surrounded by superhydrophobic (SH) surface. The combination of HL spots and SH background enables confinement of nanoliter droplets, functioning as miniaturized reactors for the solid‐phase synthesis. The polymer serves as support for nanomolar solid‐phase synthesis, while a photocleavable linker enables the release of the synthesized compounds into the droplets containing live cells. A 588 compound library of bisamides is synthesized via a four‐component Ugi reaction on the chip and products are detected via stamping of the droplet array onto a conductive substrate and subsequent matrix‐assisted laser desorption ionization mass spectrometry. The light‐induced cleavage shows high flexibility in screening conditions by spatial, temporal, and quantitative control.

Organogels (hydrophobic polymer gels) are soft materials based on polymeric networks swollen in organic solvents. They are hydrophobic and possess a high content of solvent and low surface adhesion, rendering them interesting in applications such as encapsulants, drug delivery, actuators, slippery surfaces (self-cleaning, anti-waxing, anti-bacterial), or for oil-water separation. To design functional organogels, strategies to control their shape and surface structure are required. Herein, the inherent UV photodegradability of poly(methacrylate) organogels is reported. No additional photosensitizers are required to efficiently degrade organogels (d ≈ 1 mm) on the minute scale. A low UV absorbance and a high swelling ability of the solvent infusing the organogel are found to be beneficial for fast photodegradation, which is expected to be transferrable to other gel photochemistry. Organogel arrays, films, and structured organogel surfaces are prepared, and their extraction ability and slippery properties are examined. Films of inherently photodegradable organogels on copper circuit boards serve as the first ever positive gel photoresist. Spatially photodegraded organogel films protect or reveal copper surfaces against an etchant (FeCl 3 aq. ).

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The chemistry and wettability of oxygen containing surfaces can be conveniently modified by silanization with various organosilanes which form SiO bonds on the surface. This work shows that a superhydrophobic nanoporous polymer coating can be reverted to its previous hydrophilic state by removing the fluoroalkyl silane with fluoride anions using tetrabutyl ammonium fluoride. This leads to a completely reversible process of silanization and desilanization which can be performed in less than 2 min for each step as proven by droplet shape analysis and secondary ion mass spectrometry. Additionally, the desilanization solution can be applied spatially by an automated liquid dispenser or manually by a brush, leading to patterns with different wettability, such as droplet microarrays or liquid channels.