A novel technique that enables the production of a-C:H coatings decorated either by sub-micron concave or convex structures is presented. The technique is based on several steps that involve i) pre-seeding of substrates with C:H sub-micron particles produced by a gas aggregation cluster source, ii) overcoating of the C:H particles by thin a-C:H coatings produced by plasma enhanced chemical vapor deposition and iii) optional ultrasonic liftoff of the C:H particles. The main focus is set on the characterization of the morphology of the resultant structures as well as on the comparison of their wettability. It is shown that the properties of the structured a-C:H coatings may be precisely controlled by the number of the C:H particles. Different dynamic wetting of convex and concave structures is reported, although static wettability is the same. For concave wells (maximum depth 90 rim) the dynamics of water droplet drying is similar to the one observed on smooth a-C:H films and is characterized by three well-distinguishable phases - the constant contact radius phase, the constant contact angle phase and the mixed phase - independently of the number of wells. By contrast, the increasing number of convex bumps (300 rim in height) gradually impedes the movement of a triple line which progressively suppresses the constant contact angle phase. Subsequently, the differences in the droplet drying have a strong impact on the bovine serum albumin patterns formed after the complete evaporation of droplets. Spatially irregular protein pattern is observed on smooth and well-decorated concave a-C:H coatings while a well-defined "coffee-ring" structure is formed on the a-C:H coatings decorated with convex structures.

Rf magnetron sputtering of polymers is known to allow for the synthesis of plasma polymer nanoparticles with controllable size and chemical composition. Morphology of such nanoparticles can be very diverse ranging fascinatingly from smooth to orange-peel or to cauliflower texture. The particular morphology depends on the mechanisms of nucleation and growth. Here, nitrogen-containing plasma polymer particles were synthesized by rf magnetron sputtering of nylon in a gas aggregation cluster source with variable length of the aggregation zone. Spherical particles were produced with the mean size changing from 80 to 320 nm in dependence on the time the particles spent in the source. Markedly, the chemical composition and the particle number density remained constant. The morphogenesis of the particles was investigated by Atomic Force Microscopy with super-sharp probes. The roughness exponent of 0.78, the growth exponent of 0.34 and the dynamic exponent of 0.48 were derived from the advanced surface statistics. These critical exponents point at the self-affine mode of the particle growth and evidence that the particles evolve by the accretion of polymer-forming species from the gas phase and not by coagulation. Non-fractal morphology of the particles implies that the polymer-forming species attach with the probability of less than 100% and that the accretion is accompanied by the substantial redistribution of the incoming material over the particle surface as well as by the development of the inhomogeneously distributed inner stress. Acknowledgement This work was supported by the grant GAČR-17-12994S from the Grant Agency of the Czech Republic. P. P., D. N. and R. T. also appreciate the support from the student grant SVV 260444/2017 of Charles University.

Recent works have shown the potential applicability of gas aggregation cluster sources (GAS) for the synthesis of plasma polymer nanoparticles (NPs). However, deep understanding of the fundamentals of the NP formation is still lacking because the research has been focused mainly on ex-situ analysis of the NPs rather than on the processes taking place inside the cluster source. In this work, we simultaneously employed optical emission spectroscopy, mass spectrometry and digital camera to monitor in situ the phenomena occurring during the synthesis of hydrocarbon NPs by plasma polymerization of n-hexane. The voltage on the electrode and the deposition rate of the NPs were also real-time tracked. A 3-inch RF electrode was operated at a constant power of 50 W in a 4.6 % mixture of n-hexane with argon. Cycling instabilities in the deposition process were detected. The temporal measurement of both the voltage and the deposition rate revealed the period of oscillations to be about 80 s. These oscillations correlated with the instabilities observed in the mass spectra where analogous oscillations of the n-hexane molecular peak were detected. The temporal instabilities were further proved by optical emission spectra in which the intensity of the Ar spectral line was seen to oscillate with the same period. A phenomenological description was suggested to describe the cycling growth of the NPs and their ejection from the discharge zone. Acknowledgments: The authors would like to acknowledge the contribution of the COST Action CA15107 (MultiComp) and support by the grant LTC17062 from the Ministry of Education, Youth and Sports of the Czech Republic.

Bio-decontamination of surfaces by means of atmospheric pressure plasma is nowadays extensively studied as it represents promising alternative to commonly used sterilization/decontamination techniques. The non-equilibrium atmospheric pressure plasmas were already reported to be highly effective in removal of a wide range of biological residual from surfaces. Nevertheless the kinetics of removal of biological contamination from surfaces is still not well understood as the majority of performed studies were based on ex-situ evaluation of etching rates, which did not allow investigating details of plasma action on biomolecules. This study therefore presents a real-time, in-situ ellipsometric characterization of removal of bovine serum albumin (BSA) from surfaces by low-temperature atmospheric plasma jet operated in argon. Non-linear and at shorter distances between treated samples and nozzle of the plasma jet also non-monotonic dependence of the removal rate on the treatment duration was observed. According to additional measurements focused on the determination of chemical changes of treated BSA as well as temperature measurements, the observed behavior is most likely connected with two opposing effects: the formation of a thin layer on the top of BSA deposit enriched in inorganic compounds, whose presence causes a gradual decrease of removal efficiency, and slight heating of BSA that facilitates its degradation and volatilization induced by chemically active radicals produced by the plasma. (C) 2016 Elsevier B.V. All rights reserved.

Chitosan is a linear copolymer composed of (1 / 4)elinked 2-acetamido-2-deoxy-b-D-glucan (GlcNAc) and 2-amino-2-deoxy-b-D-glucan (GlcN) units in varying proportions, having a high molecular weight and strong intraand intermolecular hydrogen bondings. Sonication has become an alternative for degrading chitosan into low-molecular-weight chitosan (LMWC), chitosan oligomers and glucosamine. In this study, chitosan was treated with sonication at 40 C and 60 C for 30 min and 120 min with various acetic acid concentrations (0.2% v/ve1% v/v); the very-low-concentration acid solution functioned both as a solvent and catalyst. After sonication, the samples were tested for changes in molecular weight, water soluble proportion of chitosan (chitosan oligomers and glucosamine), degree of deacetylation, degree of crystallinity, and morphology. The soluble and insoluble product yields at low concentration (0.5% v/v) at 40 and 60 C were 33.66e39.37 % and 32.43e34.26%, respectively. The main product was 5hydroxy methyl furfural with composition 92.16e99.43%. At high concentrations (1% v/v), the soluble product and insoluble yields were 43.72e49.74% and 43.1e50.26%, respectively. The main product was glucosamine with composition 77.75e93.16% of glucosamine. There were changes in the morphology and crystallinity of the degraded chitosan, but no change in the chemical structure. The crystallinity had a tendency to increase. The degree of deacetylation tended to decrease due to the glucosamine breakage. © 2014 Elsevier Ltd. All rights reserved.

Gas aggregation sources are nowadays rather widely used in the research community for producing nanoparticles. However, the direct diagnostics of conditions inside the source are relatively scarce. In this work, we focused on monitoring the plasma parameters and the composition of the gas during the production of the TiOx nanoparticles. We studied the role of oxygen in the aggregation process and the influence of the presence of the particles on the plasma. The construction of the source allowed us to make a 2D map of the plasma parameters inside the source.

A layer of 14 nm-sized Ag nanoparticles undergoes complex transformation when overcoated by thin films of a fluorocarbon plasma polymer. Two regimes of surface evolution are identified, both with invariable RMS roughness. In the early regime, the plasma polymer penetrates between and beneath the nanoparticles, raising them above the substrate and maintaining the multivalued character of the surface roughness. The growth (β) and the dynamic (1/z) exponents are close to zero and the interface bears the features of self-affinity. The presence of inter-particle voids leads to heterogeneous wetting with an apparent water contact angle θa = 135°. The multivalued nanotopography results in two possible positions for the water droplet meniscus, yet strong water adhesion indicates that the meniscus is located at the lower part of the spherical nanofeatures. In the late regime, the inter-particle voids become filled and the interface acquires a single valued character. The plasma polymer proceeds to grow on the thus-roughened surface whereas the nanoparticles keep emerging away from the substrate. The RMS roughness remains invariable and lateral correlations propagate with 1/z = 0.27. The surface features multiaffinity which is given by different evolution of length scales associated with the nanoparticles and with the plasma polymer. The wettability turns to the homogeneous wetting state.

Silver nanoparticle-based antibacterial nanocomposite coatings were fabricated by means of gas aggregation source of Ag nanoparticles and plasma-enhanced chemical vapour deposition of matrix material. Combination of these techniques makes it possible to independently control the amount of Ag nanoparticles in the nanocomposites, as well as properties of matrix material, such as its chemical composition or wettability. This subsequently enables to tune kinetics of silver ion release and hence the antibacterial performance of produced nanocomposites. Based on detail measurements of silver ion release from Ag/plasma polymerized hexamethyldisiloxane and Ag/SiOx nanocomposites, it may be concluded that the release rate is strongly dependent both on matrix material and amount of Ag nanoparticles present in the nanocomposite. These measurements are furthermore accompanied with tests focused on the evaluation of antibacterial potency of produced nanocomposites.

Biomimetic nano-structured films are valuable materials in various applications. In this study we introduce a fully vacuum-based approach for fabrication of such films. The method combines deposition of nanoparticles (NPs) by gas aggregation source and deposition of overcoat thin film that fixes the nanoparticles on a surface. This leads to the formation of nanorough surfaces which, depending on the chemical nature of the overcoat, may range from superhydrophilic to superhydrophobic. In addition, it is shown that by proper adjustment of the amount of NPs it is possible to tailor adhesive force on superhydrophobic surfaces. Finally, the possibility to produce NPs in a wide range of their size (45-240 nm in this study) makes it possible to produce surfaces not only with single scale roughness, but also with bi-modal or even multi-modal character. Such surfaces were found to be superhydrophobic with negligible water contact angle hysteresis and hence truly slippery.

Atmospheric air plasma treatment of chitosan solutions leads to degradation of chitosan molecules by OH radicals and is accompanied by a predominant cleavage of glycosidic linkages and by a decrease of the molecular weight. The degradation proceeds via first order kinetics with the rate constant of (5.73±0.22)×10(-6)s(-1) and the energetic yield of chitosan bond scission of (2.4±0.2)×10(-8)mol/J. Products of degradation together with intact chitosan molecules adsorb and form coatings on polypropylene foils immersed into the solution that is being plasma treated. The plasma treatment results in strong binding of chitosan to polypropylene due to the formation of covalent bonds between the activated polymer surface and chitosan molecules. Plasma-driven crosslinking is responsible for the accumulation of compressive stress which leads to the development of buckling instabilities in the chitosan coatings.

R. f. magnetron sputtering of poly(tetrafluoroethylene) in configuration of a gas aggregation source is shown to produce super-hydrophobic nano-structured coatings in which cross-linked nano-particles of fluorocarbon plasma polymer are embedded in an uncross-linked continuous (CF2)x matrix. The 20–30nm nano-particles appear in proximity of the magnetron and have cross-linked structure as a result of fast random radical recombination in the plasma. The continuous phase is formed at remote distances from the magnetron as a result of slower step-growth gas phase polymerization of CF2 bi-radicals. The matrix has highly crystalline structure in which the CF2 groups tend to adopt a 15/7 helical configuration. At least part of the macromolecules constituting the polymeric phase are oligomers with the molar mass below 1400g/mol.

Silver containing nanocomposites receive increasing attention as antibacterial coatings. In this study we report on production of such materials using combination of gas aggregation sources of Ag nanoparticles and plasma enhanced chemical vapour deposition performed in HMDSO/O2 working gas mixtures. The main attention is devoted to the investigation of solubility of Ag nanoparticles in water in dependence on the properties of matrix material and determination of antibacterial properties of produced films.