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  • Küçük Resim
    Öğe
    The comparative investigation on synthesis, characterizations of silver ion-imprinting and non-imprinting cryogels, their impedance spectroscopies and relaxation mechanisms
    (Springer, 2019) Şarkaya, Koray; Demir, Ahmet
    In the present study, a novel ion-imprinting and non-imprinting cryogel samples have been prepared using ion-imprinting technique and the dielectric properties have been investigated using an impedance spectroscopy method. In the preparation of ion-imprinted cryogel, at the first attempt, N-methacryloly-(l)-cysteine methyl ester was used as the metal complexing monomer. Ag+-imprinted poly(hydroxyethyl methacrylate-N-methacryloly-(l)-cysteine methyl ester) cryogel was produced by bulk polymerization. Poly(2-hydroxyethyl methacrylate) was selected as the basic matrix by considering properties, high chemical and mechanical stability. After removal of template (silver ions), the ion-imprinted cryogel was used for the removal of photo-film-containing materials. The dielectric properties of cryogel samples have also been investigated by impedance spectroscopy within the frequency range of 1 Hz-10 MHz. The real part of the permittivity increases at low frequencies as electrode effects become dominant. It shows a constant value at high frequencies due to dipole polarization. On the other hand, the imaginary part does not show a relaxation peak as the relaxation time of samples is very short. The frequency dependence of electrical modulus has also been investigated. The real part of electrical modulus (M ' (f)) is an indicative of negligible electrode polarization phenomenon in the test material. The behavior of the imaginary part of frequency dependent electrical modulus (M '' (f)) exhibit that the dielectric relaxation process is usually not frequency-activated state. Dielectric relaxation process occurs spontaneously due to the hopping mechanism of charge carriers.
  • Küçük Resim
    Öğe
    p(NIPAM) Kriyojelinin Hazırlanışı, Karakterizasyonu ve Termal Özelliklerinin p(NIPAM) Hidrojeli ile Karşılaştırmalı Olarak İncelenmesi
    (2020) Şarkaya, Koray
    Bu çalışmada ilk olarak, süper-gözenekli poli(N-izopropilakrilamit) (p(NIPAM)) kriyojeli, -16°C'dekriyojelasyon yöntemi ile sentezlenmiştir. Polimerizasyon işleminde, NIPAM monomer olarakkullanıldı ve çapraz bağlayıcı olarak N,N'-metilen-bis-akrilamid (MBAAm) tercih edildi. Reaksiyonkoşullarının sağlanabilmesi açısından diğer reaktifler olarak ise reaksiyon redoks başlatıcı çiftiN,N,N,N?-tetrametilen diamin (TEMED) ve amonyum persülfat (APS) varlığında polimerizasyongerçekleştirildi. Hazırlanan p(NIPAM) kriyojellerinin şişme ve makrogözeneklilik testlerininincelenmesinin yanı sıra, Fourier dönüşümlü kızılötesi (FTIR) spektroskopisi ve Yüzey TaramalıElektron mikroskobu ile karakterize edildi. p(NIPAM) kriyojellerinin termal kararlılıklarınınbelirlenebilmesi amacıyla Termal Gravimetrik Analiz (TGA) yöntemlerine başvuruldu. NIPAM bazlıkriyojellerin karakterizasyon ölçümlerinin belirlenmesinden sonra ise kriyojellerin dahil olduğu sınıfolan hidrojellere ait bu kez NIPAM-bazlı hidrojel sentezlenerek aynı koşullar üzerindenkarakterizasyon sonuçları karşılaştırıldı.
  • Küçük Resim Yok
    Öğe
    Preparation, Characterization and Investigation of Swelling Behavior of HEMA-Based Amphiphilic Semi-IPN Cryogels Containing Polymeric Linoleic Acid
    (2022) Allı, Abdulkadir; Gürel, Cansu Meltem Kaymanlı; Şarkaya, Koray
    In this study, it was aimed to synthesize and characterize a new polymeric cryogel system to be formed with polymeric linoleic acid (PLina), a vegetable oil-based polymeric fatty acid, and the widely preferred 2-hydroxyethyl methacrylate (HEMA) monomer. cryogels. For this purpose, firstly, autoxidation and hydroxylation reactions were carried out for polymeric lineloic acid, respectively. Hydroxylated polymeric lineloic acid (PLina-OH) and HEMA monomer were subjected to a cryogenic gelation reaction in the presence of N,N?-methylene bisacrylamide (MBAA) as crosslinking agent. The obtained new cryogel was characterized by FTIR, SEM, BET, TGA analyses. The swelling behavior of the synthesized PLinaOH-HEMA cryogels in water was concluded with kinetic studies. In the other hands, some of polar and non-polar other solvents was used for investigation of all cryogels to see their potentials for solvent uptake.