2011, Buschhorn, Samuel T., Wichmann, Malte H. G., Sumfleth, Jan, Schulte, Karl, Pegel, Sven, Kasaliwal, Gaurav R., Villmow, Tobias, Krause, Beate, Göldel, Andreas, Pötschke, Petra

A practical overview of possibilities and limits to characterize the state of dispersion of carbon nanotubes (CNT) in polymer based nanocomposites is given. The most important and widely available methods are discussed with practical employment in mind. One focus is the quantitative characterization of the state of dispersion in solid samples using microscopy techniques such as optical microscopy or transmission electron microscopy. For dispersions of CNTs in aqueous media, solvents or monomers a sedimentation analysis is presented. This way dispersability and dispersion state of CNTs can be assessed. Indirect methods such as electrical conductivity measurements and rheological tests, dynamic differential scanning calorimetry and mechanical test are discussed. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

2017, Luo, Jinji, Cerretti, Giacomo, Krause, Beate, Zhang, Long, Otto, Thomas, Jenschke, Wolfgang, Ullrich, Mathias, Tremel, Wolfgang, Voit, Brigitte, Pötschke, Petra

The thermoelectric properties of melt processed conductive nanocomposites consisting of an insulating polypropylene (PP) matrix filled with singlewalled carbon nanotubes (CNTs) and copper oxide (CuO) were evaluated. An easy and cheap route to switch p-type composites into n-type was developed by adding polyethylene glycol (PEG) during melt mixing. At the investigated CNT concentrations of 0.8 wt% and 2 wt% (each above the electrical percolation threshold of ∼0.1 wt%), and a fixed CuO content of 5 wt%, the PEG addition converted p-type composites (positive Seebeck coefficient (S)) into n-type (negative S). PEG was also found to improve the filler dispersion inside the matrix. Two composites were prepared: P-type polymer/CNT composites with high S (up to 45 μV/K), and n-type composites (with S up to −56 μV/K) through the addition of PEG. Two prototypes with 4 and 49 thermocouples of these p- and n-type composites were fabricated, and delivered an output voltage of 21 mV and 110 mV, respectively, at a temperature gradient of 70 K.

2015, Maitz, Manfred F.

Multiple biological, synthetic and hybrid polymers are used for multiple medical applications. A wide range of different polymers is available, and they have further the advantage to be tunable in physical, chemical and biological properties in a wide range to match the requirements of specific applications. This review gives a brief overview about the introduction and developments of polymers in medicine in general, addressing first stable polymers, then polymers with degradability as a first biological function, followed by various other functional and responsive polymers. It is shown up that biomedical polymers comprise not only bulk materials, but also coatings and pharmaceutical nano-carriers for drugs. There is subsequently an overview of the most frequently used polymer classes. The main body of the review then is structured according to the medical applications, where key requirements of the applications and the currently used polymer solutions are indicated.

2012, Krause, Beate, Mende, Mandy, Petzold, Gudrun, Boldt, Regine, Pötschke, Petra

Two main properties of carbon nanotube (CNT) materials are discussed in this contribution. First, a method to characterize the dispersability of CNT materials in aqueous surfactant solutions in presented, which also allows conclusions towards the dispersability in other media, like polymer melts. On the other hand it is shown, how the length of CNTs before and after processing, e.g., after melt mixing with thermoplastics, can be quantified. Both methods are illustrated with examples and the practical relevance is shown. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

2020, Nishime, Thalita M.C., Wagner, Robert, Kostov, Konstantin G.

In the last decade atmospheric pressure plasma jets (APPJs) have been routinely employed for surface processing of polymers due to their capability of generating very reactive chemistry at near-ambient temperature conditions. Usually, the plasma jet modification effect spans over a limited area (typically a few cm²), therefore, for industrial applications, where treatment of large and irregular surfaces is needed, jet and/or sample manipulations are required. More specifically, for treating hollow objects, like pipes and containers, the plasma jet must be introduced inside of them. In this case, a normal jet incidence to treated surface is difficult if not impossible to maintain. In this paper, a plasma jet produced at the end of a long flexible plastic tube was used to treat polyethylene terephthalate (PET) samples with different incidence angles and using different process parameters. Decreasing the angle formed between the plasma plume and the substrate leads to increase in the modified area as detected by surface wettability analysis. The same trend was confirmed by the distribution of reactive oxygen species (ROS), expanding on starch-iodine-agar plates, where a greater area was covered when the APPJ was tilted. Additionally, UV-VUV irradiation profiles obtained from the plasma jet spreading on the surface confirms such behavior.

2016, Kredl, Jana, Kolb, Juergen F., Schnabel, Uta, Polak, Martin, Weltmann, Klaus-Dieter, Fricke, Katja

Inanimate surfaces serve as a permanent reservoir for infectious microorganisms, which is a growing problem in areas in everyday life. Coating of surfaces with inorganic antimicrobials, such as copper, can contribute to reduce the adherence and growth of microorganisms. The use of a DC operated air plasma jet for the deposition of copper thin films on acrylonitrile butadiene styrene (ABS) substrates is reported. ABS is a widespread material used in consumer applications, including hospitals. The influence of gas flow rate and input current on thin film characteristics and its bactericidal effect have been studied. Results from X-ray photoelectron spectroscopy (XPS) and atomic force microscopy confirmed the presence of thin copper layers on plasma-exposed ABS and the formation of copper particles with a size in the range from 20 to 100 nm, respectively. The bactericidal properties of the copper-coated surfaces were tested against Staphylococcus aureus. A reduction in growth by 93% compared with the attachment of bacteria on untreated samples was observed for coverage of the surface with 7 at. % copper.

2019, Mičušík, Matej, Chatzimanolis, Christos, Tabačiarová, Jana, Kollár, Jozef, Kyritsis, Apostolos, Pissis, Polycarpos, Pionteck, Jürgen, Vegso, Karol, Siffalovic, Peter, Majkova, Eva, Omastová, Mária

Polymeric composites of the linear triblock copolymer poly(styrene-co-ethylene/butylene-co-styrene) grafted with maleic anhydride units (SEBS-MA) or MA modified by hydrophilic polyethylene glycol (PEG) and containing various amounts of multiwall carbon nanotubes (MWCNTs) as conducting filler—were prepared by solvent casting. The MWCNT surface was modified by a non-covalent approach with a pyrene-based surfactant to achieve a homogeneous dispersion of the conducting filler within the polymeric matrix. The dispersion of the unmodified and surfactant-modified MWCNTs within the elastomeric SEBS-MA and SEBS-MA-PEG matrices was characterized by studying the morphology by TEM and SAXS. Dynamical mechanical analysis was used to evaluate the interaction between the MWCNTs and copolymer matrix. The electrical conductivity of the prepared composites was measured by dielectric relaxation spectroscopy, and the percolation threshold was calculated. The prepared elastomeric composites were characterized and studied as humidity sensor. Our results demonstrated that at MWCNTs concentration slightly above the percolation threshold could result in large signal changes. In our system, good results were obtained for MWCNT loading of 2 wt% and an ~0.1 mm thin composite film. The thickness of the tested elastomeric composites and the source current appear to be very important factors that influence the sensing performance. © 2019 Mičušík, Chatzimanolis, Tabačiarová, Kollár, Kyritsis, Pissis, Pionteck, Vegso, Siffalovic, Majkova and Omastová.