Jindřich Matoušek

Plasma Treatment of Glass Surfaces Using Diffuse Coplanar Surface Barrier Discharge in Ambient Air

We report a study on the treatment of flat glass surfaces by ambient air atmospheric pressure plasma, generated by a dielectric barrier discharge of coplanar arrangement of the electrode system—the diffuse coplanar surface barrier discharge (DCSBD). The plasma treatment of glass was performed in both static and dynamic modes. With respect to wettability of the glass surface, treatment in static mode resulted in non-uniform surface properties, whereas dynamic mode provided a fully uniform treatment. A water contact angle measurement was used to determine the efficiency of plasma treatments in dynamic mode and also to investigate a hydrophobic recovery of plasma treated glass surfaces. The X-ray photoelectron spectroscopy measurements showed a decrease of overall carbon concentrations after plasma treatment. A deconvolution of C1s peak, showed that a short plasma treatment led to decrease of C–C bonds concentration and increases of C–O and O–C=O bond concentrations. An enhancing influence of the glass surface itself on DCSBD diffuse plasma was observed and explained by different discharge onsets and changes in the electric field distribution.

Synthesis and characterization of carbosilane dendrimer–sodium montmorillonite clay nanocomposites. Experimental and theoretical studies

Novel organic/inorganic hybrid materials with carbosilane fillers were developed. New carbosilane dendrimers of the first (Dm1) and second (Dm2) generations bearing four and eight cationic ammonium groups on their periphery were synthesized first. Their structure was elucidated by NMR spectroscopy and ESI-HRMS whereas their thermal stability was confirmed by TGA. Both dendrimers were used as organic components in the preparation of organoclays. A series of nanocomposites Dm1Mt and Dm2Mt with varied contents of dendrimers were prepared and characterized by a wide variety of analytical techniques. The analytical data show that the structure of organoclays and the ability of dendrimers to effectively interact with montmorillonite are strongly affected by their generation. Both species Dm1 and Dm2 intercalated into the interlayer space of montmorillonite increase correspondingly the basal spacing of Mt. In contrast to Dm2, increased loadings of Dm1 in suspension during the intercalation process have a negligible effect on d-spacing in the studied concentration range, as confirmed by XRD analysis. Besides unmodified Mt we also studied the interactions of dendrimers with plasma treated Mt and the results are presented. Computer modelling based mainly on Molecular Dynamics has shown the non-linear dependence of the d-spacing on the amount of dendrimers in the interlayer space within the studied dendrimer/montmorillonite mass ratio interval. The filling capacity of plasma unmodified montmorillonite with respect to both dendrimers was estimated using a combination of experimental and theoretical results.

Antimicrobial and optical properties of PET chemically modified and grafted with borane compounds

Polyethylene terephthalate (PET) foils were activated with piranha solution and grafted with selected amino compounds (cysteamine, ethylenediamine or chitosan) and then with borane compounds. Changes in their surface properties after particular modification steps were examined using electrokinetic analysis, X-ray photoelectron spectroscopy (XPS), goniometry and UV-vis spectroscopy. Several tests showed that the presence of some amino compounds and one borane cluster significantly improved the antimicrobial properties of the composites investigated. In particular, they exhibited strong antibacterial activity against Staphylococcus epidermidis but only weak activity against Escherichia coli. The samples modified with amino compounds and subsequently with borane clusters were luminescent under UV lamp irradiation. Therefore, the nanocomposites consisting of (cheap) polymer and (more expensive) borane could be used in luminophore development, medicine or environmental protection.

Organoclays with carbosilane dendrimers containing ammonium or phosphonium groups

New composite materials could reveal attractive capabilities and favourable properties. Herein, we present novel layered nanocomposites consisting of inorganic clay (montmorillonite) and cationic carbosilane dendrimers. A comparative study was performed to evaluate cationic moieties (ammonium or phosphonium) and various generations of dendrimers (first, second and third) and their influence on the characteristics of resulting materials. The target nanocomposites were characterized by XRD, TEM, TGA, IR and MAS NMR. Interestingly, with multivalent dendritic cations, as opposed to monovalent cations, we detected a new connection of cationic species to the inorganic matrix by both ammonium and phosphonium dendrimers. To evaluate the mechanism of thermal degradation of the prepared materials, non-oxidative pyrolysis coupled with analysis of the resulting products by IR and MS was performed. To illustrate the catalytic activity of the as-prepared materials, selected samples were tested as catalysts in the cycloaddition of CO2 with epoxide (allyl glycidyl ether).