This is an editorial article. It has no abstract.
Effect of Fe3O4 particles on multi-hollow morphology of poly(HEMA-divinylbenzene-styrene) microspheres prepared by Pickering suspension polymerization
S. Prymon, A. Bukowska, W. Bukowski, K. Bester, K. Hus, K. Dychton, Z. Opiekun
Vol. 12., No.12., Pages 1026-1038, 2018
Vol. 12., No.12., Pages 1026-1038, 2018
Hydroxy-functionalized polymers have been synthesized by Pickering suspension polymerization of 2-hydroxyethyl methacrylate (HEMA) with styrene (S) and divinylbenzene (DVB) in the presence of hydrophobic Fe3O4 particles.The obtained polymer microspheres were characterized using different instrumental techniques (optical microscopy, scaning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), diffuse reflection ultraviolet-visible spectroscopy (DR UV-Vis), inductively coupled plasma-optical emission spectrometry (ICP-OES), dynamic light scattering and thermal analyses) and then modified to immobilize the complexes of palladium(II) with the tetradentate ligands based on salicylaldehyde, epichlorohydrin and 2-picolylamine. The resulting polymer supported complexes were preliminarily examined as catalysts in the model Suzuki reaction between 4-bromotoluene and phenylboronic acid. It was found the polymer particles obtained as a result of the performed polymerization have composite nature and are characterized by a unique multi-hollow morphology with pores up to 50 µm in size. An advantageous effect of the Fe3O4 particles embedded in the synthesized polymer microspheres on the activity of palladium catalysts has been noted.
Polymeric biomaterials treated by nanostructured metal coatings are very efficient against a wide spectrum of nosocomial pathogens. One of the most effective ways for the preparation of such metal/polymer composites is the combination of excimer laser modification of polymeric materials and vacuum evaporation of noble metals. By this way, we successfully prepared palladium nanowire arrays (PdNWs) supported on biocompatible polyethylene naphthalate (PEN). The characterization of prepared PdNWs on the surface of PEN was accomplished by various methods, such as X-ray Photoelectron Spectroscopy (XPS), Focussed Ion Beam Scanning Electron Microscopy (FIB-SEM), and Atomic Force Microscopy (AFM). PdNWs were preferentially formed from one side of underlying ripples. Pd release in antibacterial testing was measured by Inductively coupled plasma mass spectrometry (ICP-MS). Then, the antibacterial and cytotoxic effects were evaluated by (i) drop plate method using E. coli (G–) and S. epidermidis (G+ bacteria), and (ii) WST-1 cytotoxicity assay with three model cell lines (L929, NIH 3T3, RAW 264.7), respectively. Pd-treated samples exhibited significant antibacterial effects, increasing with cultivation time. Cytotoxicity assay showed that the absorbance of PEN/PdNWs samples was mildly decreased, suggesting considerably low cytotoxic effects of PdNWs.
The full understanding of the mechanisms involved in the development of polymer blend microstructure during its processing has not yet been achieved; the understanding of blends composed by a highly elastic dispersed phase is even more indefinite. The proposal of this work is to analyze the deformation behavior of a new system composed by a partially devulcanized rubber dispersed in polypropylene using 2D and 3D images, both as complementary tools. For this purpose, ground tire rubber (GTR) was partially devulcanized by microwave irradiation for different exposure periods. After this step, each treated rubber was incorporated into recycled PP. The molded blends were analyzed using effective tools as 2D and 3D images and rheological data. In general, the polymer blends exhibited refined microstructure, especially the blend composed of the most devulcanized rubber, even though they had high values of viscosity ratio (≥4). Based on the 3D images, it is clear that breakup mechanisms of the dispersed phase, like parallel breakup, have played an important role in the evolution of the blend’s microstructure, mainly in the region of higher shear rate during processing. However, in areas where the rubber is still vulcanized, the breakup may have been caused by erosion of its surface.
Photoreactive composite thin layers with tunable wetting properties from superhydrophilic to superhydrophobic nature were prepared. To achieve extreme wetting properties, the adequate surface roughness is a crucial factor, which was achieved by the incorporation of plasmonic Ag-TiO2 particles, as polymer filler, into the smooth polymer film with adjusted hydrophilicity. The initial copolymer films were synthesized from hydrophilic 2-hydroxyethyl-acrylate (HEA) and hydrophobic perfluorodecyl-acrylate (PFDAc) monomers. In the case of hydrophobic PFDAc, the photocatalyst- roughened thin films displayed superhydrophobic behavior (γstot ~ 2.3±1.7 mJ/m2, Θ > 150°), while the roughened hydrophilic pHEA layers possessed superhydrophilicity (γstot ~ 72.1 ±0.2 mJ/m2, Θ ~ 0°). The photoactivity of the composites was presented both in solid/gas (S/G) and solid/ liquid (S/L) interfaces. According to the light-emitting diode (LED) light photodegradation tests on ethanol (EtOH) as volatile organic compound (VOC) model- molecules at the S/L interface, the superhydrophobic hybrid layer was photooxidized 88.3% of the initial EtOH (0.36 mM). At S/L interface the photocatalytic efficiency was depended on the polarity of the model pollutant molecules: the photooxidation of hydrophobic SUDAN IV (c0 = 0.25 mg/mL) dye reached 80%, while in the case of the hydrophilic Methylene Blue dye (c0 = 0.002 mg/mL) it was only 17.3% after 90 min blue LED light (λ = 405 nm) illumination.
Ultra-high molecular weight polyethylene (UHMWPE) fibers drawn at drawing ratio of 6 (pre-deformation strain 500%) demonstrating the obtained one-way shape memory effect. Artificial muscles have been manufactured in the form of coiled UHMWPE fibers. Isometric recovery stress and recovery strain of the fibers were measured during heating by using a dynamic mechanical analyzer (DMA). As a result, the fibers were capable to demonstrate large contraction of 78% (recovery strain of 93%) due to the entropic elasticity. The recovery stresses of the fibers reach up to 27 MPa. The work of stroke cycle for coiled artificial muscles with a constant stress of 1 MPa was recorded. Artificial muscles based on coiled UHMWPE fibers have a large stroke of 64 %. The structural mechanisms of muscle-like behavior were discussed.
The review is devoted to the current state of the investigation works concerning chitosan functionalization with carboxylic acids and derivatives of them, including oxidized carbon nanoparticles such as graphene oxide, oxidized nano diamonds and oxidized carbon nanotubes. The examples of a use of chitosan derivatives in the pharmacology, the regenerative medicine, and other areas are given.
Odors from materials used in new vehicles may cause satisfaction or dissatisfaction for people. This duality is due to a stimulation caused by receptors which act differently in each individual. It is already known that odors exhaling in a vehicles interior are caused by a gaseous mixture of the various materials which are volatilized, especially with the increase of internal temperature. The components of a newly manufactured automotive vehicles interior of high surface representativeness selected in this work are eight: air conditioner, ceiling liner, shelf package, rubber mats, door panel, carpet, instrument panel, and seats, which were analyzed by gas chromatography for the identification of volatile substances. The proportion of the peak area of each compound was calculated. Gas chromatography analysis identified the main substances from materials used in interior of vehicles which contribute to the new car odor: toluene, p-xylene, ethylbenzene or benzene derivatives, except in carcass of air conditioner. Polypropylene is a constituent of these components, except the rubber mats. Carbon disulfide appeared with a significant proportion of area in rubber mats and contributed in the formation of car odors.