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    Hydrophobically Associated Poly(acrylamide/octadecyl acrylate)-Carboxymethyl Cellulose Hydrogels: Synthesis, Characterization, and Shape Memory Ability
    (Springer, 2023) Olukman Sahin, Merve; Demirbilek Bucak, Celile
    In this study, hydrophobic modified poly(acrylamide/octadecyl acrylate) (poly(AAm/C18)) and poly(acrylamide/octadecyl acrylate)-carboxymethyl cellulose (poly(AAm/C18)-CMC) hydrogels with high mechanical strength and shape memory properties were synthesized by random copolymerization method. Hydrogel synthesis was successfully carried out in one step on the basis of the hydrophobic monomer units carrying alkyl side chains included in the hydrophilic polymer network, and these hydrophobes clustered in water and acted as crosslinks. Hydrogels were characterized by Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), Differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and X-ray diffractometry (XRD). The results showed that with the increase of the amount of hydrophobic monomer (C18) in the hydrogels, the crystal regions in the hydrogel structure increased. The swelling behaviour of the hydrogels was investigated as a function of the hydrophobic monomer content. Experimental swelling data confirmed the DSC and XRD results. The shape memory properties of hydrogels containing CMC were investigated. The new shape of the hydrogels was fixed by complexation between CMC and metal (M2+ and M3+ valence) ions.
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    In situ synthesis of ZnO nanoparticles in poly(vinyl alcohol) membranes and its use in separation of acetone/water mixtures via pervaporation
    (Elsevier, 2021) Olukman Sahin, Merve; Sanli, Oya
    In this study, in-situ synthesis of zinc oxide (ZnO) nanoparticles was utilized as an effective approach to prepare poly(vinyl alcohol) (PVA) and poly(vinyl alcohol)-graft-acrylonitrile/2-hydroxyethyl methacrylate (PVA-g-AN/HEMA) membranes with ZnO nanoparticles. The membranes were characterized by using Frourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-Ray diffraction (XRD) and contact angle measurements. Both of the membranes were utilized in separation of acetone/water mixtures via pervaporation technique and the optimum conditions regarding ZnO content within the membranes, acetone content in the feed solution and operating temperature were determined. PVA-g-AN/HEMA-ZnO nanocomposite membranes showed high permeation rate but low separation factor compared to PVA-ZnO nanocomposite membranes. Permeation rate and separation factor values were found to be in the range of 0.028-0.137 and 0.035-0.174 kg m(-2) h(-1), 17.61-325 and 9.4-84.5 depending on the pervaporation conditions for PVA-ZnO and PVA-g-AN/HEMA-ZnO nanocomposite membranes, respectively. (C) 2020 Elsevier B.V. All rights reserved.
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    In vitro 5-fluorouracil release properties investigation from pH sensitive sodium alginate coated and uncoated methyl cellulose/chitosan microspheres
    (Elsevier, 2024) Olukman Sahin, Merve; Sanli, Oya
    5-Fluorouracil (5-FU) has been in clinical practice for decades one of the oldest chemotherapy agents. However, intravenous administration of 5-FU requires the development of an oral controlled delivery system for improved patient compliances. For this purpose, 5-FU loaded and sodium alginate (NaAlg) coated and uncoated methyl cellulose (MC)/chitosan (CS) microspheres were prepared by emulsion crosslinking method using a mixture of water and oil. Firstly, MC/CS microspheres were prepared and then coated with NaAlg. The prepared microspheres were characterized by optical microscopy, Fourier transform infrared spectroscopy (FTIR), and differential scanning calorimetry (DSC). Microspheres were also characterized by equilibrium swelling values and drug release profiles. The in vitro drug release studies were carried out with three pH values 1.2, 6.8, and 7.4, respectively, each for 2 h. It was determined that coating the microspheres with NaAlg provides more controlled drug release, especially at pH 1.2. The effects of the preparation conditions, such as coating time, MC/CS ratio, NaAlg concentration, and crosslinker concentration on the 5-FU release were investigated.