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Carbon nanostructures were obtained by acetylene injection into an argon plasma jet in the presence of hydrogen. The samples were synthesized in similar conditions, except that the substrate deposition temperatures TD were varied, ranging from 473 to 973 K. A strong dependence of morphology, structure, and graphitization upon TD was found. We obtained vertical aligned carbon nanotubes (VA-CNTs) at low temperatures as 473 K, amorphous carbon nanoparticles (CNPs) at temperatures from about 573 to 673 K, and carbon nanowalls (CNWs) at high temperatures from 773 to 973 K. Fourier transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, elastic recoil detection analysis, X-ray photoelectron spectroscopy, and Raman spectroscopy were used to substantiate the differences in these material types. It is known that hydrogen concentration modifies strongly the properties of the materials. Different concentrations of hydrogen-bonded carbon could be identified in amorphous CNP, VA-CNT, and CNW. Also, the H : C ratios along depth were determined for the obtained materials. [ABSTRACT FROM AUTHOR]

In this work polymethylmethacrylate foil surfaces are modified using a non-thermal atmospheric pressure plasma jet generated by a discharge with bare electrodes. The study focuses on a comparison of the treatments performed using plasma generated in Ar/water vapors mixture (humid plasma) and dry Ar. Injecting small amounts of water vapors in the discharge, a substantial improvement of the polymeric foils surface wettability was obtained. For a similar improvement of the wettability, the duration of treatment with dry argon plasma is six times longer. The investigations of the treated surfaces show that the wettability of the polymeric foils is mainly improved due to the surface roughening during dry plasma treatments, while the chemical changes of the sample surface prevail in the case of humid plasma treatments. [ABSTRACT FROM AUTHOR]