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Simple and robust methods for modifying hydrophobic polymer surfaces with zwitterionic polymers using UV irradiation were developed. Two random zwitterionic copolymers consisting of either carboxybetaine or sulfobetaine methacrylamide monomers and monomers bearing a photolabile azidophenyl group were directly photoimmobilized on polymeric surfaces (polyester, polyethylene and polystyrene) via covalent interactions in a spatially controlled manner. These copolymers were also electrospun to form self-standing mats. The modified surfaces were characterized by X-ray photoelectron spectroscopy, atomic force microscopy, infrared spectroscopy and contact angle measurements. The electrospinning method involved the use of a trifluoroethanol solution with a copolymer concentration in the range from 2 to 10 wt.%. BHK 21 cell adhesion to both modified surfaces and mats was dramatically reduced compared to unmodified surfaces. [ABSTRACT FROM AUTHOR]

[Display omitted] One of the highlighted properties of Ti 3 C 2 T x MXene compared to other 2D nanomaterials is its hydrophilicity. However, the broad range of static contact angles of Ti 3 C 2 T x reported in the literature is misleading. To elucidate the experimental values of the static contact angles and get reproducible contact angle data, it is wiser to perform the advancing and receding contact angle measurements on smooth and compact Ti 3 C 2 T x layers and focus on deep understanding of the physical basis behind the wettability, which is provided by contact angle hysteresis. Measurements of the advancing and receding contact angle on mono-, bi, and trilayer Ti 3 C 2 T x on two different substrates were performed. As substrates, UV-ozone treated silicon wafer and silicon wafer functionalized by (3-aminopropyl)triethoxysilane, were used. The values of the advancing contact angle on Ti 3 C 2 T x on both substrates were proved to be independent of the number of Ti 3 C 2 T x layers, demonstrating a negligible effect of the background substrate wettability. In addition, a giant contact angle hysteresis (44–52 °) was observed on very smooth surface, most likely as a result of chemical heterogeneity arising from the diversity of surface terminal groups (F, O, and OH). The findings reported in this study provide a comprehensive understanding of the wettability of MXene. [ABSTRACT FROM AUTHOR]

By using methyl orange template, polypyrrole nanotubes were obtained by the oxidative polymerization of pyrrole. The nanotubes were carbonized in inert atmosphere to nitrogen-enriched carbon nanotubes. These were subsequently coated with 20 wt% of polypyrrole prepared in the absence or the presence of anionic dyes (methyl orange or Acid Blue 25). The morphology of all the samples was examined by the electron microscopies, FTIR and Raman spectroscopies. Moreover, X-ray photoelectron spectroscopy and elemental analysis were used to prove the chemical structure and the successful coating process. Electron paramagnetic resonance analysis was used to calculate the spin concentrations. Significant impact of coating method is evidenced with neat polypyrrole coating providing a two-fold capacitance increase compared to uncoated nanotubes, while coating in the presence of Acid Blue 25 decreasing it slightly. With respect to oxygen reduction reaction, coatings irreversibly transformed in the first few cycles in the presence of the products of O 2 reduction, presumably hydrogen peroxide, altering the oxygen reduction mechanism. This transformation allows the tailoring of the polymeric shell, over ORR active carbonaceous core, and tuning of the catalyst selectivity and optimization of materials performance for a given application – from alkaline fuel cells to hydrogen peroxide generation. [ABSTRACT FROM AUTHOR]