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3. Improved Adhesion of Bacterial Cellulose on Plasma-Treated Cotton Fabric for Development of All-Cellulose Biocomposites.

Author

Ogrizek, Linda, Lamovšek, Janja, Primc, Gregor, Leskovšek, Mirjam, Vesel, Alenka, Mozetič, Miran, and Gorjanc, Marija

Subjects
COTTON textiles, PLASMA potentials, CELLULOSE, TEXTILE industry, PROBLEM solving, COTTON fibers, OXYGEN plasmas
Abstract

Cellulose produced by bacteria (BC) is considered a promising material for the textile industry, but the fragile and sensitive nature of BC membranes limits their broad applicability. Production of all-cellulose biocomposites, in which the BC is cultivated in situ on a cotton fabric, could solve this problem, but here a new issue arises, namely poor adhesion. To overcome this challenge, cotton fabric was modified with low-pressure oxygen plasma in either afterglow, E-mode, or H-mode. All-cellulose biocomposites were prepared in situ by placing the samples of cotton fabric in BC culture medium and incubating for 7 days to allow BC microfibril networks to form on the fabric. Modification of cotton fabric with oxygen plasma afterglow led to additional functionalization with polar groups, and modification with oxygen plasma in H-mode led also to etching and surface roughening of the cotton fibers, which improved the adhesion within the biocomposite. In addition, these biocomposites showed higher deformation capacities. Modification of the cotton fabric over a longer period in E-mode was found to be unsuitable, as this caused strong etching, which led to the defibrillation of cotton fibers and poor adhesion of BC. This study highlights the potential of low-pressure plasma treatment as an environmentally friendly method to improve the performance of cellulose-based biocomposites. [ABSTRACT FROM AUTHOR]

Published
2024
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4. Plasma Treatment of Nanocellulose to Improve the Surface Properties.

Author

Primc, Gregor and Mozetič, Miran

Subjects
*PLASMA gases, *MECHANICAL behavior of materials, *NONEQUILIBRIUM plasmas, *SURFACE properties, *WETTING
Abstract

Nanocellulose is among the most promising materials for enhancing the mechanical properties of polymer composites. Broad application is, however, limited by inadequate surface properties. A standard technique for tailoring the surface composition and wettability of polymers is a brief treatment with non-equilibrium gaseous plasma, but it often fails when treating materials with a large surface-to-mass ratio, such as cellulose nanofibers. In this paper, the theoretical limitations are explained, the approaches reported by different groups are reviewed, and the results are interpreted. The treatment of dry nanocellulose is limited by the ability of uniform treatment, whereas the plasma treatment of nanocellulose dispersed in liquids is a slow process. The methods for enhancing the treatment efficiency for both dry and water-dispersed nanocellulose are explained. [ABSTRACT FROM AUTHOR]

Published
2024
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10. Recent progress in cellulose hydrophobization by gaseous plasma treatments

Author

Primc, Gregor, Vesel, Alenka, Zaplotnik, Rok, Gorjanc, Marija, Gselman, Peter, Lehocký, Marián, Mozetič, Miran, Primc, Gregor, Vesel, Alenka, Zaplotnik, Rok, Gorjanc, Marija, Gselman, Peter, Lehocký, Marián, and Mozetič, Miran

Abstract

Cellulose is an abundant natural polymer and is thus promising for enforcing biobased plastics. A broader application of cellulose fibers as a filler in polymer composites is limited because of their hydrophilicity and hygroscopicity. The recent scientific literature on plasma methods for the hydrophobization of cellulose materials is reviewed and critically evaluated. All authors focused on the application of plasmas sustained in fluorine or silicon-containing gases, particularly tetrafluoromethane, and hexamethyldisiloxane. The cellulose materials should be pre-treated with another plasma (typically oxygen) for better adhesion of the silicon-containing hydrophobic coating. In contrast, deposition of fluorine-containing coatings does not require pre-treatment, which is explained by mild etching of the cellulose upon treatment with F atoms and ions. The discrepancy between the results reported by different authors is explained by details in the gas phase and surface kinetics, including the heating of samples due to exothermic surface reactions, desorption of water vapor, competition between etching and deposition, the influence of plasma radiation, and formation of dusty plasma. Scientific and technological challenges are highlighted, and the directions for further research are provided.

Published
2024

11. Evolution of the Surface Wettability of Vertically Oriented Multilayer Graphene Sheets Deposited by Plasma Technology.

Author

Paul, Domen, Zaplotnik, Rok, Primc, Gregor, Vesel, Alenka, and Mozetič, Miran

Subjects
PLASMA-enhanced chemical vapor deposition, GRAPHENE, WETTING, OXYGEN plasmas, HIGH-frequency discharges, METALLIC surfaces, CONTACT angle, PLASMA deposition
Abstract

Carbon deposits consisting of vertically oriented multilayer graphene sheets on metallic foils represent an interesting alternative to activated carbon in electrical and electrochemical devices such as super-capacitors because of the superior electrical conductivity of graphene and huge surface–mass ratio. The graphene sheets were deposited on cobalt foils by plasma-enhanced chemical vapor deposition using propane as the carbon precursor. Plasma was sustained by an inductively coupled radiofrequency discharge in the H mode at a power of 500 W and a propane pressure of 17 Pa. The precursor effectively dissociated in plasma conditions and enabled the growth of porous films consisting of multilayer graphene sheets. The deposition rate varied with time and peaked at 100 nm/s. The evolution of surface wettability was determined by the sessile drop method. The untreated substrates were moderately hydrophobic at a water contact angle of about 110°. The contact angle dropped to about 50° after plasma treatment for less than a second and increased monotonously thereafter. The maximal contact angle of 130° appeared at a treatment time of about 30 s. Thereafter, it slowly decreased, with a prolonged deposition time. The evolution of the wettability was explained by surface composition and morphology. A brief treatment with oxygen plasma enabled a super-hydrophilic surface finish of the films consisting of multilayer graphene sheets. [ABSTRACT FROM AUTHOR]

Published
2024
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20. Fundamentals of thin film depth profiling by glow discharge optical emission spectroscopy.

Author

Vesel, Alenka, Zaplotnik, Rok, Primc, Gregor, and Mozetic, Miran

Subjects
GLOW discharges, EMISSION spectroscopy, OPTICAL spectroscopy, DEPTH profiling, THIN films, PLASMA gases
Abstract

Glow discharge optical emission spectroscopy (GDOES) is a useful technique for qualitative plasma characterization. It also enables depth profiling of solid materials upon exposure of samples to energetic positively charged ions from gaseous plasma, providing specifics of both surface- and gas-phase collision phenomena that are considered. The early stages of developing GDOES useful for the determination of surface composition and depth profiling of solid materials are reviewed and analyzed, stressing the contribution of early authors. The advantages as well as drawbacks of the GDOES technique are presented and discussed. The recent applications of this technique for depth profiling of various materials are presented, and the directions for constructing a laboratory-scale device are provided. [ABSTRACT FROM AUTHOR]

Published
2023
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23. Generation of Neutral Chemically Reactive Species in Low-Pressure Plasma

Author

Primc, Gregor

Subjects
Materials Science (miscellaneous), Biophysics, General Physics and Astronomy, Physical and Theoretical Chemistry, Mathematical Physics
Abstract

The surface finish of organic and inorganic materials treated by gaseous plasma usually depends on the fluxes and fluencies of chemically reactive species such as molecular radicals. In low-pressure plasmas, the dissociation of molecules to parent atoms depends on the production rate in the gas phase and on the loss rate on surfaces. The processing will be efficient if the loss rate is minimized. The methods for minimizing the loss rate and thus increasing the processing efficiency are presented and discussed. The dissociation fraction of simple molecules exceeds 10% providing the plasma-facing materials are smooth with a low coefficient for heterogeneous surface recombination. The density of atoms in a plasma reactor increases with increasing pressure reaching a maximum and decreases with further pressure increase, which is explained by two competing processes. The energy efficiency also exhibits a maximum, which may be as high as 30% if plasma is sustained by electrodeless high-frequency discharges. Optimization of energy efficiency is not only beneficial for the costs of material processing but also for the prevention of excessive heating of treated materials. The latter is particularly important for organic materials because the surface functional groups are not stable but decay with increasing surface temperature.

Published
2022

46. First Slovene Plasma Day

Author

Dahle, Sebastian, Avramidis, Georg, Zaplotnik, Rok, Primc, Gregor, Vesel, Alenka, Mozetič, Miran, Sebastian Dahle, Marko Petrič, Andreja Kutnar, Janez Kovač, Aleš Ugovšek, Simona Rataj, Miha Humar, Jure Žigon, and Davor Kržišnik

Subjects
Plasma, Surface Modification
Abstract

On September 30th, the First Slovene Plasma Day took place in Ljubljana, Slovenia. This dataset contains the program, abstracts, and the three presentations that were given during the day. A video summary is available online via: https://youtu.be/4a9kUy-WbG0, Contributors list the main organizers of the event.

Published
2019

47. Preparation of hierarchically structured polystyrene surfaces with superhydrophobic properties by plasma-assisted fluorination

Author

Minařík, Martin, Wrzecionko, Erik, Minařík, Antonín, Grulich, Ondřej, Smolka, Petr, Musilová, Lenka, Junkar, Ita, Primc, Gregor, Ptošková, Barbora, Mozetič, Miran, Mráček, Aleš, Minařík, Martin, Wrzecionko, Erik, Minařík, Antonín, Grulich, Ondřej, Smolka, Petr, Musilová, Lenka, Junkar, Ita, Primc, Gregor, Ptošková, Barbora, Mozetič, Miran, and Mráček, Aleš

Abstract

The nanotexturing of microstructured polystyrene surfaces through CF4 plasma chemical fluorination is presented in this study. It is demonstrated that the parameters of a surface micropore-generation process, together with the setup of subsequent plasma-chemical modifications, allows for the creation of a long-term (weeks) surface-stable micro- and nanotexture with high hydrophobicity (water contact angle >150 degrees). Surface micropores were generated initially via the time-sequenced dosing of mixed solvents onto a polystyrene surface (Petri dish) in a spin-coater. In the second step, tetrafluoromethane (CF4) plasma fluorination was used for the generation of a specific surface nanotexture and the modulation of the surface chemical composition. Experimental results of microscopic, goniometric, and spectroscopic measurements have shown that a single combination of phase separation methods and plasma processes enables the facile preparation of a wide spectrum of hierarchically structured surfaces differing in their wetting properties and application potentials.

Published
2019

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