The ability to control the degree of spin, or rotational velocity, for catalytic swimming devices opens up the potential to access well defined spiralling trajectories, enhance cargo binding rate, and realise theoretically proposed behaviour such as chiral diffusion. Here we assess the potential to impart a well-defined spin to individual catalytic Janus swimmers by using glancing angle metal evaporation onto a colloidal crystal to break the symmetry of the catalytic patch due to shadowing by neighbouring colloids. Using this approach we demonstrate a well-defined relationship between the glancing angle and the ratio of rotational to translational velocity. This allows batches of colloids with well-defined spin rates in the range 0.25 to 2.5 Hz to be produced. With reference to the shape and thickness variations across the catalytically active shapes, and their propulsion mechanism we discuss the factors that can lead to the observed variations in rotational propulsion.

The field of active colloids is attracting significant interest to both enable applications and allow investigations of new collective colloidal phenomena. One convenient active colloidal system that has been much studied is spherical Janus particles, where a hemispherical coating of platinum decomposes hydrogen peroxide to produce rapid motion. However, at present producing these active colloids relies on a physical vapor deposition (PVD) process, which is difficult to scale and requires access to expensive equipment. In this work, it is demonstrated that Pickering emulsion masking combined with solution phase metallization can produce self‐motile catalytic Janus particles. Comparison of the motion and catalytic activity with PVD colloids reveals a higher catalytic activity for a given thickness of platinum due to the particulate nature of the deposited coating. This Pickering emulsion based method will assist in producing active colloids for future applications and aid experimental research into a wide range of active colloid phenomena.

Research on superwetting surfaces/coatings that artificially mimic biological surfaces/systems has a long history, and still garners significant worldwide interest as it is expected to provide superior solutions to conventional engineering approaches that attempt to solve challenges facing mankind. To broaden the utility of these superwetting surfaces/coatings, there is a strong demand for these surfaces to exhibit multiple practical functionalities. Here, the progress being made in multifunctional surfaces with superwettability is explored. In each section, state‐of‐the‐art works are summarized and the concepts, materials, processes, and the effects of both physical (smooth or structured surfaces) and chemical (low or high surface energies) factors on the resulting surface are described. Finally, the outlook of this prospective research field is considered, and its future directions briefly discussed, with a focus on preserving longevity in both functionality and structural integrity to produce truly useful biomimetic surfaces/coatings.

Chemically and spatially micropatterned surfaces have been successfully prepared for a number of diverse applications, including water/fog harvesting, screen printing, microfluidics, and cell/protein assays. While there have been quite some reports on micropatterned surfaces, less is known about the factors that influence dynamic surface wettability. To that end, smooth checkerboard-like micropatterned hydrophobic/(super)hydrophilic surfaces (2, 5, 10, 20 μm pattern sizes) with regions of matching/mismatching contact angle hysteresis (CAH) were prepared on the basis of a simple chemisorption/photopatterning of monolayers. The effects of regional wettability/CAH and pattern size on the overall dynamic wettability were then examined by measuring the dynamic contact angles (CAs) and substrate tilt angles (θ T ) of water. It was found that the dynamic wettability on samples with matching regional CAH remained unchanged, even when using hydrophilic regions or changing the pattern size. In contrast, surfaces containing mismatching CAH regions pinned water droplets, leading to overall dynamic wetting properties markedly dependent on pattern size. In addition, the experimental data did not match values predicted by the Cassie equation because dynamic wetting behavior is dominated not by interfacial area but by the interactions of the liquid and solid at the three-phase contact line.