Pokročilé polymerní materiály a kompozit

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    Effect of Chitin Nanocrystal Deacetylation on a Nature-Mimicking Interface in Carbon Fiber Composites
    (MDPI, 2024-05-01) Abdellatif, Abdelmohsen Moustafa; Radwan, Rasha; Kalina, Lukáš; Vishakha, Vishakha; Kaprálková, Ludmila; Němeček, Pavel; Jančář, Josef; Kelnar, Ivan
    The formation of a rigid, tough interface based on a nacre-like structure in carbon fiber (CF) composites is a promising way to eliminate low delamination resistance. An effective method of coating CFs is electrophoretic deposition (EPD), which, in the case of dissimilar components like graphene oxide (GO) and polymeric glue, usually requires chemical bonding/strong interactions. In this work, we focus on chitin nanocrystals (ChNCs), leading to an excellent mechanical performance of artificial nacre, where favorable interactions and bonding with GO are controlled by degrees of deacetylation (5, 15, and 30%). We prepared coatings based on GO/ChNC adducts with 95/5, 90/10, 50/50, and 25/75 ratios using optimized EPD conditions (pH, concentration, voltage, and time). The prepared materials were characterized using FTIR, TEM, XPS, SEM, DLS, and XRD. SEM evaluation indicates the formation of a homogeneous interlayer, which has a fair potential for chemical bonding with the epoxy matrix. Short-beam testing of epoxy matrix composites indicates that the coating does not decrease stiffness and has a relatively low dependence on composition. Therefore, all coatings are promising for a detailed study of delamination resistance using laminate samples. Moreover, facile EPD from the water solution/suspension has a fair potential for industrial applications.
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    Naphthalene-stilbenes as effective visible-light sensitizers to study the effect of diluent and nanofillers on in situ photopolymerization and 3D-VAT printing process
    (ROYAL SOC CHEMISTRY, 2024-01-23) Tomal, Wiktoria; Galuszka, Karolina; Lepcio, Petr; Pilch, Maciej; Chachaj-Brekiesz, Anna; Korčušková, Martina; Ortyl, Joanna
    This study presents novel photoinitiating systems based on diaryliodonium salt (IOD) and 1-amino-4-methyl-6-styrylnaphthalene-2-carbonitrile derivatives developed as universal IOD photosensitizers. These systems' spectroscopic characteristics, electrochemical behavior, and thermodynamic parameters were investigated to determine the optimal two-component photoinitiating system for light-initiated polymerization, including free-radical and cationic reactions. This versatility in initiating both types of reactions was utilized to explore the dilution effect of non-reactive and two different reactive (cationic, free-radical) diluents. The best formulation was chosen according to Fourier-transform infrared spectroscopy (FTIR), photorheology, thermogravimetric analysis (TGA), and dynamic mechanical analysis (DMA) and tested for the preparation of functional nanocomposites with two types of nanofiller: silver oxide (Ag2O) and hydroxyapatite (HA). The manufacturing process based on additive technology was analyzed according to FTIR spectroscopy and viscosity changes. The results show the high potential of the newly developed photosensitizers in practical applications and 3D-VAT printing.
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    ChemFET gas nanosensor arrays with alignment windows for assembly of single nanowires
    (Springer, 2023-04-13) Chmela, Ondřej; Gablech, Imrich; Sadílek, Jakub; Brodský, Jan; Vallejos Vargas, Stella
    This work focuses on the fabrication and characterization of ChemFET (Chemical Field-Effect Transistor) gas nanosensor arrays based on single nanowire (SNW). The fabrication processes include micro and nanofabrication techniques enabled by a combination of ultraviolet (UV) and e-beam lithography to build the ChemFET structure. Results show the integration and connection of SNWs across the multiple pairs of nanoelectrodes in the ChemFET by dielectrophoresis process (DEP) thanks to the incorporation of alignment windows (200-300 nm) adapted to the diameter of the NWs. Measurements of the SNW ChemFET array's output and transfer characteristics prove the influence of gate bias on the drain current regulation. Tests upon hydrogen (H-2) and nitrogen dioxide (NO2) as analyte models of reducing and oxidizing gases show the ChemFET sensing functionality. Moreover, results demonstrate better response characteristics to H-2 when the ChemFET operates in the subthreshold regime. The design concepts and methods proposed for fabricating the SNW-based ChemFET arrays are versatile, reproducible, and most likely adaptable to other systems where SNW arrays are required.
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    Liposomes Affect Protein Release and Stability of ITA-Modified PLGA-PEG-PLGA Hydrogel Carriers for Controlled Drug Delivery
    (AMER CHEMICAL SOC, 2023-12-22) Kadlecová, Zuzana; Sevriugina, Veronika; Lysáková, Klára; Rychetský, Matěj; Chamradová, Ivana; Vojtová, Lucy
    Fat grafting, a key regenerative medicine technique, often requires repeat procedures due to high-fat reabsorption and volume loss. Addressing this, a novel drug delivery system uniquely combines a thermosensitive, FDA-approved hydrogel (itaconic acid-modified PLGA-PEG-PLGA copolymer) with FGF2-STAB, a stable fibroblast growth factor 2 with a 21-day stability, far exceeding a few hours of wild-type FGF2's stability. Additionally, the growth factor was encapsulated in "green" liposomes prepared via the Mozafari method, ensuring pH protection. The system, characterized by first-order FGF2-STAB release, employs green chemistry for biocompatibility, bioactivity, and eco-friendliness. The liposomes, with diameters of 85.73 +/- 3.85 nm and 68.6 +/- 2.2% encapsulation efficiency, allowed controlled FGF2-STAB release from the hydrogel compared to the unencapsulated FGF2-STAB. Yet, the protein compromised the carrier's hydrolytic stability. Prior tests were conducted on model proteins human albumin (efficiency 80.8 +/- 3.2%) and lysozyme (efficiency 81.0 +/- 2.7%). This injectable thermosensitive system could advance reconstructive medicine and cosmetic procedures.
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    Carboxymethyl starch as a reducing and capping agent in the hydrothermal synthesis of selenium nanostructures for use with three-dimensional-printed hydrogel carriers
    (ROYAL SOC, 2023-10-11) Vishakha, Vishakha; Abdellatif, Abdelmohsen Moustafa; Michalička, Jan; White, Paul B.; Lepcio, Petr; Tinoco Navarro, Lizeth Katherine; Jančář, Josef
    The hydrothermal method is a cost-effective and eco-friendly route for preparing various nanomaterials. It can use a capping agent, such as a polysaccharide, to govern and define the nanoparticle morphology. Elemental selenium nanostructures (spheres and rods) were synthesized and stabilized using a tailor-made carboxymethyl starch (CMS, degree of substitution = 0.3) under hydrothermal conditions. CMS is particularly convenient because it acts simultaneously as the capping and reducing agent, as verified by several analytical techniques, while the reaction relies entirely on green solvents. Furthermore, the effect of sodium selenite concentration, reaction time and temperature on the nanoparticle size, morphology, microstructure and chemical composition was investigated to identify the ideal synthesis conditions. A pilot experiment demonstrated the feasibility of implementing the synthesized nanoparticles into vat photopolymerization three-dimensional-printed hydrogel carriers based on 2-hydroxyethyl methacrylate (HEMA). When submersed into the water, the subsequent particle release was confirmed by dynamic light scattering (DLS), promising great potential for use in bio-three-dimensional printing and other biomedical applications.