Cold plasma assisted laser synthesis of nanoparticles in liquids and applications

U ovom radu proučavali smo utjecaje različitih metoda impregnacije nanočestica na polimere. Ovo istraživanje je potaknuto željom da se pronađe što efikasniji način impregnacije nanočestica na polimere zbog njihovog raznolikog i vrlo korisnog utjecaja. Nanočestice same po sebi polimerima mijenjaju razna optička, fizikalna i kemijska svojstva te se tako mijenja kut močenja, učinkovitost apsorpcije, površinska mikrobiološka svojstva, funkcionalnost itd. S druge strane, tretiranje polimera atmosferskim plazmenim mlazom povećava hrapavost površine, a time najčešće polimeri postaju hidrofilniji, odnosno povećava se efektivna površina koja sudjeluje u impregnaciji nanočestica. Pretpostavka je da ćemo kombiniranjem ta dva procesa poboljšati željenje rezultate i povećati učinkovitost impregnacije polimera nanočesticama. Kako bi mogli impregnirati nanočestice, prvo smo ih sintetizirali metodom laserske ablacije u tekućini. Neke od dobivenih koloidnih otopina nanočestica smo analizirali pomoću spektrofotometra kako bi dobili ovisnosti aprobancije o valnim duljinama. Zanimao nas je kut močenja te smo mjerili kontaktne kuteve svih polimera za razne tekućine (deionizirana voda, koloidne otopine srebra, zlata i aluminija) što nam je dalo podatak o hidrofobnosti samih polimera. Pri procesu sinteze nanočestica laserskom ablacijom u tekućini, snimali smo optičke emisijske spektre plazme koja se stvara interakcijom laserske zrake i mete. Usporedbom spektra laserske ablacije mete na zraku sa Planckovim krivuljama zračenja crnog tijela odredili smo temperaturu mete. Za razliku od spektara laserske ablacije na zraku, koji uz kontinuum imaju jako izražene emisijske linije atoma i iona, spektri laserske ablacije u tekućini su dominantno kontinuirani. Ovi spektri ukazuju na to da u koloidnim otopinama nanočestica, dobivenih laserskom ablacijom u tekućini, prevladavaju nanočestice i njihovi aglomerati, a ne pojedinačni atomi i ioni. Optičke emisijske spektre smo snimali i pri procesu tretiranja polimera atmosferskim plazmenim mlazom. U ovom smo slučaju, uz neke linije atoma, primjetili i molekulske vrpce dušika te linije molekulskog iona dušika. U spektrima se ne vidi velika razlika između plazmenog mlaza na zraku i plazmenom mlaza pri interakciji sa polimerom. Uzorke smo impregnirali nanočesticama pomoću više metoda. Kao kontrolu smo koristili metodu centrifuge jer je to najčešća metoda impregnacije nanočestica. Pri toj metodi, jedan uzorak smo predtretirali plazmenim mlazom kako bi vidjeli postoji li razlika zbog utjecaja plazme. Ispostavilo se da je uzorak predtretiran plazmenim mlazom lakše impregnirati nanočesticama. Druga metoda koju smo koristili je metoda kapanja koloidne otopine na uzorak. Nakon isparavanja otopine, na polimeru ostaju samo nanočestice. Treća metoda impregnacije koju smo koristili je metoda gdje smo na polimer nakapali veću količinu koloidne otopine i tretirali ju plazmenim mlazom sve dok otopina nije isparila. Dobivene uzorke smo analizirali pomoću AFM-a , SEM-a i EDS-a. Iz rezultata se vidi da je najefikasnija metoda impregnacije polimera nanočesticama treća navedena metoda. Na slikama tih uzoraka vidimo najveću hrapavost i najveći broj nanočestica. U metodičkom dijelu rada obrađena je tema ‘Optički linijski spektri’ za 4. razred srednje škole. U ovoj nastavnoj jedinici cilj je upoznati učenike sa pojmom optičkog spektra posebno linijskih spektara. Učenici će naučiti razliku između kontinuiranog, emisijskog i apsorpcijskog optičkog spektra te kakvi izvori svjetlosti daju takve spektre.In this thesis we studied different methods of impregnating nanoparticles into polymers. This research was prompted by a desire to find a more efficient way of impregnating nanoparticles into polymers because of their diverse and very useful impact. Nanoparticles by themselves alter the optical, physical and chemical properties of polymers and change the angle of wettability, absorption efficiency, surface microbial properties, functionality etc. On the other hand, the atmospheric pressure plasma treatment of polymers increases effective surface roughness, which makes polymers more hydrophilic, and so the effective surface that participates in the impregnation of nanoparticles increases. The assumption is that in combining the two processes we will achieve the desired results and increase the efficiency of the impregnation of nanoparticles into polymers. In order to impregnate nanoparticles, first synthesised them through laser ablation in liquid. Some of the obtained colloidal solutions of nanoparticles were analysed using a spectrophotometer to assess the absorbancy spectrum. We were interested in the angle of wettability and we measured the contact angles of polymers for a variety of liquids (deionised water, a colloidal solution of silver, gold and aluminum) which provided us with information on the hydrophobicity of the polymer itself. In the process of the synthesis of nanoparticles by laser ablation in liquid, we aquired optical emission spectra of the plasma generated by the interaction of the laser beam and the target. By comparing the spectrum of laser ablation targets in the air with Planck's black body radiation curves, we determined the temperature of the target. Unlike the spectra of laser ablation in air, that along the continuum has highly expressed emission lines of atoms and ions, spectra of laser ablation in a liquid are predominantly continuous. These spectra indicate that the colloidal solution of nanoparticles obtained by laser ablation in a liquid, are predominant by nanoparticle agglomerates and not individual atoms and ions. Optical emission spectra were also recorded during the process of treatment the polymers with an atmospheric pressure plasma jet. In this case, with a few atomic lines, we detected molecular bands of nitrogen and lines of nitrogen molecular ion. The spectra did not show a big difference between the plasma jet in air and plasma jet in interaction with the polymer. The samples were impregnated by nanoparticles using multiple methods. As a control, we used spin coating because it is the most common method of impregnating nanoparticles. In this method, a sample was pretreated by a plasma jet to study the difference due to the influence of plasma. It was found that the samples which were pretreated by plasma jet were easier impregnated with nanoparticles. Another method we used was drop coating. After evaporating the solvent, only nanoparticles should remain. The third impregnation method that was used was treating the larger amount of colloidal solution on polymer by the plasma jet until the liquid from the solution evaporated. The resulting samples were analysed by AFM, SEM and EDS. The results showed that the most effective method of polymer impregnation by nanoparticles is the third mentioned method. These samples show the greatest roughness and the highest number of nanoparticles. The methodical part of the thesis covers ‘Optical line spectra’ for the fourth year of high school. In this unit the aim was to acquaint students with the concept of the optical spectrum, particulary the line spectrum. Students will learn the difference between the continuous, emission and absorption optical spectrums and what light sources give these spectra

On diagnostics of an annular-shape radio-frequency plasma jet operating in argon at atmospheric conditions

One of the driving forces behind the development of cold plasma sources at atmospheric pressure is their application in the biomedical field. In this respect, radio-frequency (RF) plasma jets are of particular importance due to their possible safe operation on humans and the generation of the high amount of reactive species. For this reason, we designed an RF plasma jet in co-axial geometry with the possibility of aerosol introduction, where its characteristics were evaluated by electrical diagnostics, optical emission and laser scattering spectroscopy. The RF plasma jet operation and stability of diffuse mode were analysed based on energy balance. It was observed that alpha-mode diffuse discharge characterised by an effluent length up to 5 mm was sustained at a power density below 30 W cm(-3). The gas and rotational temperature were determined by means of spectroscopy methods and compared with the results of direct laser scattering. It was established that the gas temperature obtained from N-2 emission of transition C(3)n(u) -> B(3)n(g) (0, 2) is highly overestimated whereas the gas temperature estimated from OH transition A(2)sigma+ -> X(2)n(i) (0, 0) gave a reasonable agreement with both Rayleigh and Raman spectroscopy. Based on the Rayleigh scattering method, uniform gas temperature distribution in the discharge effluent was found at a power below 15 W with the average temperature below 340 15 K. The low gas temperature of argon plasma jets would allow use of this source in temperature-sensitive material applications including skin treatments

Radio-frequency plasma in combination with aerosol injection for biomedical applications

Radiofrequency plasma for biomedical applications generated in coaxial geometry at atmospheric pressure was investigated. The plasma was characterized by key parameters, including gas temperature and electron density. It was shown that OH rotational temperature is in agreement with the temperature estimated by Rayleigh and Raman scattering techniques. RF plasma was combined with an aerosol injection for better control of the treated skin temperature and topical drugs delivery

Showcase of tools for preparing, modifying and describing thin lms for energy conversion devices with special attention on plasma phenomenology

This paper draws attention to the wide range of capacities of the roup, including chemical and physical deposition, modification and processing techniues, and advanced characterisations. In particular, this work demystifies the new plasma discharge method for the synthesis of thin films, which is still under development. Specifically, the coupled spark plasma ablation deposition (SPAD) can be performed at almost ambient conditions in various configurations with respect to several deposition reactors, proving powerful, versatile, green, and easy-to-use nature of the method. Composition-wise, up to 4 element material can be derived combining pure electrodes, however the derived composition can be broader when using alloy electrodes. It is indisputable that SPAD is capable of producing thin films at a significantly reduced cost compared to other methods.which we want to put in use for the constituent layers of the last generation of energy conversion devices. enerally, the SPAD optimisation envelope heavily differs for the case of intended products nanoparticle vs thin film, or metal vs metal oxide, or crystalline vs amorphous. Here, we will provide a more detailed description of the ablation parameters that are necessary to achieve the various crystallinities of nanomaterials. Copper nanoparticles and thin films were derived via SPAD and additionally thermally treated. (Micro)structural and thermal evolution points out to interesting development of the surface morphologies. In addition, the results enabled the correlation between oxygen plasma concentration and order of crystallinity in the thin films

Plasma-laser assisted synthesis of nanoparticles for antibacterial coatings

The “green synthesis” of colloidal nanoparticles and their application for the antibacterial coatings is based on the plasma-laser assisted ablation in liquids. Nanoparticles are synthesized through the process of laser ablation of target in water, which enables additional advantages in comparison with the other standard wet chemical synthesis, such as simplicity and complete utilization of materials. Furthermore, these nanoparticles are used and tested for antibacterial coatings on polymers, where they are grafted or imbedded through atmospheric pressure plasma assisted processes. The advantages of different coatings made from those nanoparticles are presented as well.Plasmatexinfo:eu-repo/semantics/publishedVersio

Analysing mouse skin cell behaviour under a non-thermal kHz plasma jet

Plasma jets are extensively used in biomedical applications, particularly for exploring cell viability behaviour. However, many experimental parameters influence the results, including jet characteristics, secondary liquid chemistry and protocols used, slowing research progress. A specific interest of the presented research was skin cell behaviour under a non-thermal kHz plasma jet—a so-called cold plasma jet—as a topical skin treatment. Our research was focused on in vitro mouse skin cell direct plasma treatment with argon as an operating gas. The research was complemented with detailed gas-phase diagnostics and liquid-phase chemical analysis of the plasma and plasma-treated medium, respectively. The obtained results showed that direct plasma jet treatment was very destructive, leading to low cell viability. Even with short treatment times (from 35 s to 60 s), apoptosis was observed for most L929 murine fibroblasts under approximately the same conditions. This behaviour was attributed to plasma species generated from direct treatment and the types of cell lines used. Importantly, the research exposed important points that should be taken under consideration for all further research in this field: the urgent need to upgrade and standardise existing plasma treatment protocols of cell lines; to monitor gas and liquid chemistries and to standardise plasma discharge parameters

White paper on the future of plasma science and technology in plastics and textiles

International audienceThis white paper considers the future of plasma science and technology related to the manufacturing and modifications of plastics and textiles, summarizing existing efforts and the current state-of-art for major topics related to plasma processing techniques. It draws on the frontier of plasma technologies in order to see beyond and identify the grand challenges which we face in the following 5–10 years. To progress and move the frontier forward, the paper highlights the major enabling technologies and topics related to the design of surfaces, coatings and materials with nonequilibrium plasmas. The aim is to progress the field of plastics and textile production using advanced plasma processing as the key enabling technology which is environmentally friendly, cost-efficient, and offers high-speed processing

Photodegradation of Methylene Blue and Rhodamine B Using Laser-Synthesized ZnO Nanoparticles

In this paper we examined the photocatalytic efficiency of a laser-synthesized colloidal solution of ZnO nanoparticles synthesized by laser ablation in water. The average size of the obtained colloidal ZnO nanoparticles is about 47 nm. As revealed by electron microscopy, other nanostructures were also present in the colloidal solution, especially nanosheets. A photocatalytic degradation of UV-irradiated Methylene Blue and Rhodamine B solutions of different concentration in the presence of different ZnO catalyst mass concentrations was studied in order to examine their influence on photodegradation rates. ZnO nanoparticles have shown high photocatalytic efficiency, which is limited due to different effects related to UV light transmittivity through the colloidal solution. Therefore, increasing catalyst concentration is effective way to increase photocatalytic efficiency up to some value where photodegradation rate saturation occurs. The photodegradation rate increases as the dye concentration decreases. These findings are important for water purification applications of laser-synthesized ZnO nanoparticles

Improving sensing properties of entangled carbon nanotube-based gas sensors by atmospheric plasma surface treatment

Entangled multi-walled carbon nanotubes (MWCNTs) on polyurethane (PUR) after Ar plasma-treatment and He plasma-treatment have been tested as gas sensors for ethanol sensing. It was found that plasma-treated sensors exhibit higher sensitivity compared to the non-treated samples along with different ethanol concentration. Non-treated sensors exhibit similar sensor response with the increase in ethanol concentration, while Ar plasma-treated sensors displays ~5 times improvement and He plasma-treated sensors show ~3 times improvement with an increase in ethanol concentration. The sensitivity of the plasma-treated sensors is also stable for following two-weeks after the preparation compared to the non-treated sensor. Entangled nanotube network exhibits a significant shift in the baseline resistance after both plasma-treatments. The response time of the sensor was increased after the plasma-treatment, while the recovery was rather quick. Surface analyses revealed that plasma-treatment did not make any significant morphological changes. Thus, the improvements in stability and sensitivity after plasma-treatment are attributed to the plasma-enhanced surface modification and formation of functional bonds on the surface of nanotubes, which are sensitive to the ethanol vapour. © 2020Slovenian Research Agency (ARRS)Slovenian Research Agency - Slovenia [P2-0082, L2-6769]; Ministry of Education, Youth and Sports of the Czech Republic-Program NPU I [LO1504]; Operational Program Research and Development for Innovations - European Regional Development FundEuropean Union (EU); National budget of the Czech Republic [CZ.1.05/2.1.00/19.0409]; AD FUTURA, Public Scholarship, Development, Disability, and Maintenance Fund of the Republic of Sloveni