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In this work, non-equilibrium atmospheric-pressure plasma was introduced over an aqueous solution as a medium to depolymerise lignin employing an applied voltage of 10 kV and a frequency of 10 kHz. As a starting material, lignin was extracted from Japanese cedar wood flour utilising a deep eutectic solvent (DES) at 50–120 °C. The Fourier-transform infrared (FT–IR) spectra indicated that lignin was extracted from the Japanese cedar wood flour in this temperature range. Additionally, the ultraviolet–visible (UV–Vis) spectra of the liquid fraction of the products at 280 nm revealed the high lignin content of the extracts. Gel permeation chromatography (GPC) revealed that the average molecular weight of the lignin was 400–700 Da. Matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOF MS) illustrated that the prolonged discharge plasma treatment concurrently promoted the further depolymerisation reaction and repolymerisation of the lignin-derived compounds. [ABSTRACT FROM AUTHOR]

In this study, an atmospheric‐pressure nanosecond impulse discharge initiated above the pyrrole microemulsion surface is applied to polymerize pyrrole and obtain a polypyrrole film. The films obtained under different number of plasma discharge times and duration of argon gas input time are investigated using a field emission scanning electron microscope. Results show that the roughness and thickness of the polypyrrole film can be tuned by controlling discharge times and the gas feed time. Four‐point sheet resistance measurements of the films reflect that those with a smoother and more complete surface have better electrical conductivity. The films are identified as polypyrrole by Fourier‐transform infrared spectroscopy, X‐ray diffraction, and X‐ray photoelectron spectrometry. Also, N2 is a critical factor in polymerizing polypyrrole and the gas–liquid plasma polymerization mechanism, which has three steps, is discussed. [ABSTRACT FROM AUTHOR]