Geometric reconfigurations in cellular structures have recently been exploited to realize adaptive materials with applications in mechanics, optics, and electronics. However, the achievable symmetry breakings and corresponding types of deformation and related functionalities have remained rather limited, mostly due to the fact that the macroscopic geometry of the structures is generally co‐aligned with the molecular anisotropy of the constituent material. To address this limitation, cellular microstructures are fabricated out of liquid crystalline elastomers (LCEs) with an arbitrary, user‐defined liquid crystal (LC) mesogen orientation encrypted by a weak magnetic field. This platform enables anisotropy to be programmed independently at the molecular and structural levels and the realization of unprecedented director‐determined symmetry breakings in cellular materials, which are demonstrated by both finite element analyses and experiments. It is illustrated that the resulting mechanical reconfigurations can be harnessed to program microcellular materials with switchable and direction‐dependent frictional properties and further exploit ”area‐specific” deformation patterns to locally modulate transmitted light and precisely guide object movement. As such, the work provides a clear route to decouple anisotropy at the materials level from the directionality of the macroscopic cellular structure, which may lead to a new generation of smart and adaptive materials and devices.

For inorganic metathesis and reduction reactivity, mechanochemistry is demonstrating great promise towards both nanoparticles and organometallics syntheses.

Hydrogenation reactions are one of the pillars of the chemical industry, with applications from bulk chemicals to pharmaceuticals manufacturing. The ability to selectively add hydrogen across double and/or triple bonds is key in the chemist’s toolbox, and the enabling component in the development of sustainable processes. Traditional solution-based approaches to hydrogenation reactions are tainted by significant consumption of energy and production of solvent waste. This review highlights the development and applications of recently emerged solvent-free approaches to conduct the hydrogenation of organic molecules using mechanochemistry, i.e. chemical transformations induced or sustained by mechanical force. In particular, we will show how mechanochemical techniques such as ball-milling enable catalytic or stoichiometric metal-mediated hydrogenation reactions that are simple, fast, and are conducted under significantly milder conditions compared to traditional solution routes. Importantly, we highlight the current challenges and opportunities in this field, while also identifying exciting cases in which mechanochemical hydrogenation strategies lead to new, unique targets and reactivity.