Yazar "Abdullah, Turdimuhammad" seçeneğine göre listele

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    4D printing of self-healing and shape-memory hydrogels sensitive to body temperature
    (Elsevier ltd, 2025) Aydın, Gamze; Abdullah, Turdimuhammad; Okay, Oğuz
    The development of thermoresponsive shape-memory hydrogels (SMHs) that combine robust mechanical properties, self-healing capabilities, and 4D printing potential holds great promise for advanced biomedical and smart material applications. Such hydrogels with trigger temperatures close to but below 37 degrees C are ideal for biomedical use. Despite their potential, developing SMHs that meet the right trigger temperature along with sufficient mechanical strength remains a significant challenge. We present here a simple strategy to create 4Dprinted mechanically robust, self-healing and shape-memory supramolecular hydrogels with a Young's modulus and tensile strength of 51 f 1 MPa, and 6.0 f 0.3 MPa, respectively. They exhibit a trigger temperature between 32 degrees C and 40 degrees C that can be adjusted by the composition of the hydrogel network. The hydrogels are prepared by terpolymerizing hydrophobic, crystallizable hexadecyl acrylate (C16A), hydrophilic N,N-dimethyl acrylamide (DMAA), and methacrylic acid (MAAc) monomers in the presence of TPO photoinitiator using a commercial stereolithography (SLA) device without any solvent, or cross-linker. Strong hydrogen bonding interactions between DMAA and MAAc units contribute to the mechanical properties of the hydrogels by creating reversible cross-links while the hexadecyl side chains of C16A units further increase the mechanical strength by forming crystalline domains in the hydrogels with a melting temperature between 32 and 40 degrees C. All the hydrogels exhibit complete heat-induced self-healing and shape-memory functions due to their entropic elasticity. The successful 4D printing of shapes like a flower and a paper clip showcases the adaptability of these hydrogels for functional devices such as smart packaging and drug delivery systems.
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    Design of electrospun hydrophobically modified polyacrylic acid hydrogel nanofibers and their application for removal of ciprofloxacin
    (Springer, 2025) İlyasoğlu, Gülmire; Abdullah, Turdimuhammad; Okay, Oğuz; Koyuncu, İsmail
    The global water scarcity crisis has been exacerbated by the increasing demand for clean water and water pollution caused by the persistent release of pharmaceuticals such as ciprofloxasin, into water systems. The biodegradation and adsorption potential of CIP is crucial for its elimination in wastewater treatment systems. However conventional methods in wastewater treatment plant (WWTP) often struggle to efficiently eliminate of CIP from water due to its chemically stability and nonbiodegradability. Many researchers observed that CIP was not biodegraded even after 48 days in municipal WWTP, therefor no CIP removal occurred. The objective of this study was to investigate adsorption potential of CIP using a designed electrospun nanofiber. Within the scope of this purpose, we prepared electrospun acrylic acid (AAc)-based hydrogels modified with n-hexadecyl acrylate (C16A) for the first time and evaluated their efficacy in removing CIP from water. Our results show that the desired fiber size and surface smoothness can be obtained in the electrospun hydrogel containing 35 mol% of C16A. As a result, the AAc-based hydrogel nanofiber containing 35 mol% C16A exhibited superior adsorption properties. The adsorption efficiency of the hydrogel for CIP removal from aqueous medium was as high as 98% under equilibrium conditions. The adsorption process was found to follow the pseudo-second-order model, which suggests chemisorption as the dominant mechanism. Isothermal analysis showed that the adsorption fit well with the Langmuir model, suggesting single layer adsorption on a uniform surface. These results highlight the potential of AAc-based hydrogels for the sustainable removal of pharmaceuticals from wastewater, addressing a critical need in environmental contaminant management.
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    Melt-processable and electrospinnable shape-memory hydrogels
    (Wiley, 2024) Abdullah, Turdimuhammad; Altınkök, Çağatay; Okay, Oğuz
    Due to their ability to adapt to subtle changes in response to various external and internal stimuli, smart hydrogels have become increasingly popular in research and industry. However, many currently available hydrogels suffer from poor processability and inferior mechanical properties. For example, the preparation of a hydrogel network that can be subjected to melt processing and electrospinning is challenging. Herein, a series of mechanically strong, shape-memory hydrogels based on polyacrylic acid (PAAc) chains containing 20-50 mol% of crystallizable n-octadecylacrylate (C18A) segments are prepared by an organosolv method followed by in situ physical cross-linking via hydrophobic interactions. The hydrogels exhibit a reversible strong to weak gel transition at 50-60 degrees C and can be melt-processed at 60-100 degrees C, depending on the molar fraction of C18A. Additionally, the hydrogels can be dissolved in chloroform/ethanol mixture to form a viscous solution, which can then be used to produce a nanofibrous network by electrospinning. Effects of polymer concentration, volume ratio of solvents, and mole fraction of C18A on electrospinning are investigated to produce smooth, uniform nanofibers with small fiber diameter. The produced nanofibers, while maintaining their chemical structure, show significantly improved water adsorption capacity, enhanced mechanical properties, and fast shape-memory performance.