Browsing by Author "Bunyatova, Ulviya"

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Fabrication and Characterization of PVA/ODA-MMT-Poly(MA-Alt-1-Octadecene)-G-Graphene Oxide E-Spun Nanofiber Electrolytes and Their Response to Bone Cancer Cells
(2016) Rzayev, Zakir M. O.; Salimi, Kouroush; Bunyatova, Ulviya; Acar, Selim; Salamov, Bahtiyar; Turk, Mustafa; 26838849; J-5194-2019
This work presents a new approach to fabrication and characterization of novel polymer nanofiber electrolytes from intercalated PVA/ODA-MMT nanocomposite as a matrix polymer and encapsulated graphene oxide (GO) nanosheets with amphiphilic reactive copolymer as partner polymers using electrospinning method. The chemical and physical structures, surface morphology, thermal behaviors and electric conductivity of nanocomposites and nanofibers were investigated using analyses methods including FTIR, XRD, SEM, DSC-TGA and conductivity analysis. Significant improvements in nanofiber morphology and size distribution were observed when GO and reactive organoclay were incorporated as reinforcement fillers into various matrix/partner solution blends. The structural factors of matrix-partner polymer nanocomposite particles with higher zeta-potential play important roles in both chemical and physical interfacial interactions and phase separation processing and also lead to the formation of nanofibers with unique surface morphologies and good conductivities. The cytotoxic, necrotic and apoptotic effects of chosen nanofibers on osteocarcinoma cells were also investigated. These multifunctional, self-assembled, nanofibrous surfaces can serve as semi-conductive and bioactive platforms in various electrochemical and bio-engineering processes, as well as reactive matrices used for the immobilization of various biopolymer pfecursors. (C) 2015 Elsevier B.V. All rights reserved.
Multifunctional electroactive electrospun nanofiber structures from water solution blends of PVA/ODA-MMT and poly(maleic acid-alt-acrylic acid): effects of Ag, organoclay, structural rearrangement and NaOH doping factors
(2016) Simsek, Murat; Rzayev, Zakir M.O.; Bunyatova, Ulviya
Novel multifunctional colloidal polymer nanofiber electrolytes were fabricated by green reactive electrospinning nanotechnology from various water solution/dispersed blends of poly (vinyl alcohol-co-vinyl acetate) (PVA)/octadecyl amine-montmorillonite (ODA-MMT) as matrix polymer nanocomposite and poly(maleic acid-alt-acrylic acid) (poly(MAc-alt-AA) and/or its Ag-carrying complex as partner copolymers. Polymer nanofiber electrolytes were characterized using FTIR, XRD, thermal (DSC, TGA-DTG), SEM, and electrical analysis methods. Effects of partner copolymers, organoclay, in situ generated silver nanoparticles (AgNPs), and annealing procedure on physical and chemical properties of polymer composite nanofibers were investigated. The electrical properties (resistance, conductivity, activation energy) of nanofibers with/without NaOH doping agent were also evaluated. This work presented a structural rearrangement of nanofiber mats by annealing via decarboxylation of anhydride units with the formation of new conjugated double bond sites onto partner copolymer main chains. It was also found that the semiconductor behaviors of nanofiber structures were essentially improved with increasing temperature and fraction of partner copolymers as well as presence of organoclay and AgNPs in nanofiber composite.
A New Modeling Approach for Stability of Micro/Nano Bubbles
(2021) Dogan, Mustafa; Bunyatova, Ulviya; Ferhanoglu, Onur
Microbubbles and nanobubbles have several characteristics that are comparable with millimeter- and centimeter-sized bubbles. These characteristics are their small size, which results in large surface area and high bioactivity, low rising velocity, decreased friction drag, high internal pressure, large gas dissolution capacity, negatively charged surface, and ability to be crushed and form free radicals. Controlling and modeling fundamental properties such as nucleation and of the dynamics of these bubbles is key to successfully exploiting their potential in the growing number of applications such as biomedical diagnosis and therapy, antimicrobial in aquaculture, environment, engineering, stock raising and marine industry. Laser-generated bubble dimensions can be characterized with an optical setup employing a high power continuous wave green laser for bubble generation. In this work, non-resonant, self-excited due to structurally nonlinear properties of the hydrogel, bubble formation was modeled as functions of well-controlled parameters of the colloidal media that is multi-layered and anisotropic, engineered uniquely. Copyright (C) 2021 The Authors.
Novel Colloidal Nanofiber Electrolytes From PVA-Organoclay/Poly(MA-alt-MVE), and Their NaOH and Ag-Carrying Polymer Complexes
(2016) Simsek, Murat; Rzayev, Zakir M. O.; Acar, Selim; Salamov, Bahtiyar; Bunyatova, Ulviya; 2-s2.0-84956644446; J-5194-2019
Novel multifunctional polymer nanofiber electrolytes with covalence crosslinked structures from various solution blends of reactive intercalated poly(vinyl alcohol)/octadecylamine montmorillonite (as a matrix polymer), poly(maleic anhydride-alt-methyl vinyl ether) (as a partner polymer) and their NaOH-absorbing and Ag-carrying polymer complexes were fabricated via electrospinning. Chemical, physical, morphological, and electrical properties of nanofiber structures were investigated by FTIR, XRD, SEM, and electrical analysis methods. Ag precursors in fiber composites significantly improved phase separation processing, fiber morphologies, diameter distributions, and electrical properties of the fibers. In situ generation of Ag nanoparticles and their distribution on nanofiber surfaces during fiber formation occurred via complex formation between silver cations and electronegative functional groups from both matrix and partner polymers as stabilizing/reducing agents. Electrical resistance and conductivity strongly depended on matrix/partner polymer ratios and absorption time of NaOH solution on nanofibers. Addition of NaOH changed the electrical properties of fiber structures from almost dielectric state to excellent conductivity form. The fabricated unique nanofiber electrolytes are promising candidates for applications in power and fuel cell nanotechnology, electrochemical, and bioengineering processes as reactive semiconductive platforms. (C) 2015 Society of Plastics Engineers
Novel Colloidal Nanofiber Semiconductor Electrolytes from Solution Blends of PVA/ODA-MMT, Poly (Itaconic Anhydride-Alt-2-Vinyl-1,3-Dioxalan) and Its Ag-Carrying Polymer Complex by Reactive Electrospinning
(2016) Rzayev, Zakir M. O.; Simsek, Murat; Bunyatova, Ulviya; Salamovd, Bahtiyar; J-5194-2019
Colloidal polymer nanofibers as non-crystalline solid electrolytes were fabricated by using solution blends of polyvinyl alcohol/octadecyl amine-montmorillonite, alternating copolymer of itaconic anhydride with 2-vinyl-1,3-dioxalane and their Ag-carrying complexes by electrospinning. Chemical-physical structures, morphology, thermal and electrical properties of nanofiber electrolytes were investigated to evaluate their influences on the conductivity and resistance parameters. Successful chemical cross-linking of PVA matrix by reactive partner copolymer was observed via ring-opening esterification/cross-linking. A covalence bridge of partner copolymer between PVA macromolecules not only reinforced the network but also provided extra ion charged sites. Effects of alternating copolymer fraction, organoclay, in situ generated silver nanoparticles, and structural factors on the conductivity of nanofiber thin films were estimated. Conductivity and resistance parameters strongly depended on temperature, conduct time, morphology and in situ structural rearrangements during electrospinning. Addition of reactive organoclay and Agcarrying copolymer significantly improved the conductivity due to enhancing nanofiber structures with carboxylate ion charge sites. (C) 2015 Elsevier B.V. All rights reserved.
Novel Multifunctional Colloidal Carbohydrate Nanofiber Electrolytes with Excellent Conductivity and Responses to Bone Cancer Cells
(2015) Gokmen, Fatma Ozge; Rzayev, Zakir M. O.; Salimi, Kouroush; Bunyatova, Ulviya; Acar, Selim; Salamov, Bahtiyar; Turk, Mustafa; 26344321; J-5194-2019
This work presents a new approach to fabricating novel polymer nanofiber composites (NFCs) from water solution blends of PVA (hydrolyzed 89%)/ODA-MMT and Na-CMC/ODA-MMT nanocomposites as well as their folic acid (FA) incorporated modifications (NC-3-FA and NC-4-FA) through green electrospinning nanotechnology. The chemical and physical structures and surface morphology of the nanofiber composites were confirmed. Significant improvements in nanofiber morphology and size distribution of the NFC-3-FA and NFC-4-FA nanofibers with lower average means 110 and 113 nm compared with those of NFC-1/NFC-2 nanofibers (270 and 323 nm) were observed. The structural elements of polymer NFCs, particularly loaded partner NC-2, plays an important role in chemical and physical interfacial interactions, phase separation processing and enables the formation of nanofibers with unique morphology and excellent conductivity (NFC-3-FA 3.25 x 10(-9) S/cm and NFC-4-FA 8.33 x 10(-4) S/cm). This is attributed to the higher surface contact areas and multifunctional self-assembled supramacromolecular nanostructures of amorphous colloidal electrolytes. The anticancer activity of FA-containing nanofibers against osteocarcinoma cells were evaluated by cytotoxicity, apoptotic and necrotic analysis methods. (C) 2015 Elsevier Ltd. All rights reserved.