Showing papers by "Igor Luzinov published in 2020"

Adhesion and Stability of Nanocellulose Coatings on Flat Polymer Films and Textiles.

Abstract: Renewable nanocellulose materials received increased attention owing to their small dimensions, high specific surface area, high mechanical characteristics, biocompatibility, and compostability. Nanocellulose coatings are among many interesting applications of these materials to functionalize different by composition and structure surfaces, including plastics, polymer coatings, and textiles with broader applications from food packaging to smart textiles. Variations in porosity and thickness of nanocellulose coatings are used to adjust a load of functional molecules and particles into the coatings, their permeability, and filtration properties. Mechanical stability of nanocellulose coatings in a wet and dry state are critical characteristics for many applications. In this work, nanofibrillated and nanocrystalline cellulose coatings deposited on the surface of polymer films and textiles made of cellulose, polyester, and nylon are studied using atomic force microscopy, ellipsometry, and T-peel adhesion tests. Methods to improve coatings' adhesion and stability using physical and chemical cross-linking with added polymers and polycarboxylic acids are analyzed in this study. The paper reports on the effect of the substrate structure and ability of nanocellulose particles to intercalate into the substrate on the coating adhesion.

Highly Oil-Repellent Thermoplastic Boundaries via Surface Delivery of CF3 Groups by Molecular Bottlebrush Additives.

Abstract: We fabricated thermoplastic surfaces possessing extremely limited water and oil wettability without employment of long-chain perfluoroalkyl (LCPFA) substances. Namely, by taking advantage of the st...

Zinc oxide: reduced graphene oxide nanocomposite film for heterogeneous photocatalysis

Abstract: The nanocomposite film based on zinc oxide nanostructures and reduced graphene oxide bilayer (ZnO/rGO) was synthesized, characterized and tested for the photodegradation of model organic dye (methyl orange) in water. Specifically, the nanorods of zinc oxide were obtained by the hydrothermal methods on the surface of rGO bilayers deposited on the quartz surface. The kinetics of dye photodegradation was studied via measurement of variation of the optical density at the maximum observed for the dye at 465 nm. The photodegradation efficiency of methyl orange (MO) was found to be increased from 70 to 85% when the nanocomposite material was used instead of pure ZnO nanostructures. The reaction rate constants calculated using the first-order approximation were equal to 7.2 × 10−3 min−1, 1 × 10−3 min−1 and 1.4 × 10−2 min−1 for ZnO nanorods, rGO bilayer, and ZnO/rGO nanocomposite, respectively. Hence, the rate constants clearly indicate that ZnO and rGO are functioning in a synergistic manner in the fabricated nanocomposite photocatalyst. It is necessary to point that the sample keeps its integrity after multiple experiments that is important for practical applications. The obtained results evidently demonstrate potential of the nanocomposite films based on ZnO nanostructures and rGO bilayers for production of the efficient catalysts.

Effect of number of –CF3 groups in tails of polyester on surface wettability of coatings: synthesis and characterization of PFPE based polyesters with three -CF3 groups in tails

Abstract: Perfluoropolyethers-based (PFPE) oligomeric polyesters (FOP) with fluorinated tails have emerged as highly stable and nontoxic materials for water and oil repellency, specifically as low surface energy additives to engineering thermoplastics. To investigate the effects of number of –CF3 groups in tails of polyesters on oleophobicity of coatings, FOP with three –CF3 groups in tails (PFoxa) was synthesized via polycondensation reaction of isophthaloyl acid chloride with PFPE alcohols. A model, FOP with a –CF3 group in tails (P3) was used for comparison. To obtain oleophobic surfaces, FOP polyesters were blended with oleophilic polyethylene terephthalate (PET) at different concentrations. The morphology and surface wettability of surfaces were determined by atomic force microscopy and contact angle measurements, respectively. It was demonstrated that when FOPs were added to PET film, they bring significant water and oil repellency to the thermoplastic boundary. By comparing PET/PFoxa with PET/P3 films, it was found that the wettability of films significantly affected by number of –CF3 end-groups. More groups reduce the oil and water repellency due to their conformational entropy penalty on the surface.