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The manufacture of microscale-modulated coatings (periodic, porous stacks with a thin base layer) under mass-production conditions was investigated experimentally to establish robust process parameters. Copper powders (average diameter of 100 μm) were compacted on a copper substrate under controlled pressure, temperature, surface geometry and processing sequences (e.g., sintering before and after compaction). Porosity, stack height, pitch and base thickness of coatings were measured. Results show that a minimum temperature of 350 • C and pressure of 25 MPa are required for permeable coatings, when sintering is carried out after compaction. When 'sintering before compaction' is followed, pressure values in excess of 100 MPa are needed and surfaces from this approach block the pores and diminish permeability. Pool boiling heat transfer experiments were conducted on selected coatings, showing that the best enhancement is by low-pressure compation coatings.

Herein, we report a regioselective visible-light-induced organophotoredox catalytic difunctionalization method to prepare β-hydroxysulfides using aryl alkenes and aryl thiols as substrates. The reaction provides a wide substrate scope of aryl alkenes (from simple styrene to complex bioactive compounds) and aryl thiols (from diverse heteroaromatic thiols to nonhetero­aromatic thiols) (total 45 examples, up to 88% yield). Based on the combined experimental and computational studies, we demonstrate that in situ generated hydroperoxyl radicals from O2 in air react with benzylic radicals, which restrains the reaction between benzylic radicals and the acidic form of thiols in a classical thiol–ene radical reaction. We show that difunctionalization is possible due to the choice of bases, diluted substrate concentrations, increment in catalyst loading, and selection of suitable aryl thiols under aerobic conditions. Considering the biological importance of heteroaromatic thiols and the lack of methods to install them, our approach offers a platform to derive various β-hydroxysulfides that contain aromatic elements.

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