Browsing by Author "Tasdelen, M. A."
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Item Open Access In situ preparation of thermoset/clay nanocomposites via thiol-epoxy click chemistry(Springer Verlag, 2018) Purut, Koc, O.; Bekin, Acar, S.; Uyar, Tamer; Tasdelen, M. A.A series of thermoset/clay nanocomposites are prepared by thiol-epoxy click reaction using commercially available starting compounds at ambient conditions in very good yields. The incorporation and exfoliation of clay nanolayers in the thermoset matrix are confirmed by FT-IR, XRD and TEM analyses. The influence of clay loadings on the thermal and mechanical analyses is investigated and all nanocomposites exhibit improved properties than that of the pristine thermoset. The nanocomposite containing 1% montmorillonite by weight has the most improved mechanical properties due to its highly exfoliated structure resulting in efficient interactions between clay and polymer matrix. A further increase of the clay loading results in the aggregation of clay plates to form intercalated structures leading to deteriorated thermal and mechanical properties of nanocomposites.Item Open Access In situ synthesis of polymer / clay nanocomposites by type II photoinitiated free radical polymerization(Wiley, 2011-08-15) Altinkok, C.; Uyar, Tamer; Tasdelen, M. A.; Yagci, Y.A new synthetic route for the preparation of poly(methyl methacrylate)/montmorillonite (PMMA/MMT) nanocomposites was reported. In this method, first 4-(dimethylamino)benzoate group was incorporated into silicate layers of clay by esterification reaction and used to produce PMMA/MMT nanocomposites by in situ Type II photoinitiated free radical polymerization. In situ photopolymerization of methyl methacrylate through into the silicate layers by either visible or UV light irradiation leads to PMMA/MMT nanocomposites. Copyright © 2011 Wiley Periodicals, Inc.Item Open Access Poly(epsilon caprolactone)/clay nanocomposites via host-guest chemistry(Elsevier Ltd, 2015) Arslan, M.; Tasdelen, M. A.; Uyar, Tamer; Yagci, Y.Cyclodextrin-modified montmorillonite (MMT-CD) has been prepared from commercial montmorillonite clay (Closite 30B) containing two hydroxyl groups by reacting succinic anhydride through esterification. Poly(epsilon caprolactone) (PCL)/clay nanocomposites are prepared by host-guest chemistry between MMT-CD as host and PCL, hydrophobic polymer as guest. The structures of the intermediates and final nanocomposite are investigated in detail by FT-IR XRD, TEM, DSC and TGA measurements. The intercalated/exfoliated morphologies are determined by combined XRD and TEM analyses. Thermal stabilities of all nanocomposites are improved by the addition of MMT-CD compared to the neat polymer. The DSC data confirm that the crystallinity of PCL is slightly increased by increasing clay loading. © 2015 Elsevier Ltd. All rights reserved.Item Open Access Polyhedral oligomeric silsesquioxane-based hybrid networks obtained via thiol-epoxy click chemistry(Springer, 2017) Bekin Acar, S.; Ozcelik, M.; Uyar, Tamer; Tasdelen, M. A.A series of hybrid networks based on polyhedral oligomeric silsesquioxane (POSS) were prepared by thiol-epoxy click reaction using commercially available octakis-glycidyl-POSS (G-POSS), trimethylolpropane triglycidyl ether, and trimethylolpropane tris(3-mercaptopropionate) as monomers. The click reaction was simply catalyzed by lithium hydroxide which proceeded readily at ambient conditions in very good yields. The incorporation of G-POSS into the network was clearly determined by transmission electron microscopy, FTIR, and 1H-NMR spectroscopy techniques performed with a model study using 1-butane thiol and G-POSS molecules. The homogeneous distribution of G-POSS up to 5 wt% in the hybrid network was apparently confirmed by morphological investigations. By increasing G-POSS content higher than 5 wt%, the heterogeneous dispersion of G-POSS was determined from the tensile strength measurements. The significant decrease in tensile strength was possible due to the agglomeration of G-POSS. On the other hand, thermal properties of hybrid networks were compared together by thermogravimetric analyses, where all samples exhibited one-step degradation in the range of 220–500 °C. The thermal decomposition of hybrid network led to complete degradation of the organic part and favored the formation of stable carbonaceous and inorganic residues as char. Thus, the char yields of hybrid networks were increased to 6.2, 7.8, 10.1, 12.7, and 15.1% by G-POSS loadings from 0 to 15 wt%. This improvement was also a proof of the incorporation of G-POSS into the hybrid networks that resulted in high heat-resistant POSS-based hybrid networks compared to a sample without G-POSS.Item Open Access Polymer/clay nanocomposites through multiple hydrogen-bonding interactions(John Wiley and Sons Inc., 2015) Aydin, M.; Uyar, Tamer; Tasdelen, M. A.; Yagci Y.An 2-ureido-4[1H]pyrimidinone (UPy) motif with self-association capability (through quadruple hydrogen bonds) was successfully anchored onto montmorillonite clay layers. Polymer/clay nanocomposites were prepared by specific hydrogen bonding interactions between surface functionalized silica nanoclays and UPy-bonded supramolecular poly(ethylene glycol) or poly(É-caprolactone). The mixed morphologies including intercalated layers with a non-uniform separation and exfoliated single layers isolated from any stack were determined by combined X-ray diffraction and transmission electron microscopic measurements. Thermal analyses showed that all nanocomposites had higher decomposition temperatures and thermal stabilities compared with neat polymer. The differential scanning calorimetric data implied that the crystallinity of polymers did not show essential changes upon introduction of organomodified UPy clays.Item Open Access Polystyrene / clay nanocomposites by atom transfer radical nitroxide coupling chemistry(Wiley, 2013) Aydin, M.; Tasdelen, M. A.; Uyar, Tamer; Jockusch, S.; Turro, N. J.; Yagci, Y.An efficient protocol, atom transfer radical nitroxide coupling chemistry, for the preparation of polymer/clay nanocomposites via grafting-onto strategy with well-defined polymer, which were synthesized via atom transfer radical polymerization, has been described. The radical coupling, taking place between the clay layers, not only leads to attached polymer chains but also to successful nanocomposite formation with highly exfoliated morphology. Copyright © 2012 Wiley Periodicals, Inc.Item Open Access Polysulfone / clay nanocomposites by in situ photoinduced crosslinking polymerization(Wiley, 2011) Dizman, C.; Ates, S.; Uyar, Tamer; Tasdelen, M. A.; Torun, L.; Yagci, Y.PSU/MMT nanocomposites are prepared by dispersing MMT nanolayers in a PSU matrix via in situ photoinduced crosslinking polymerization. Intercalated methacrylate-functionalized MMT and polysulfone dimethacrylate macromonomer are synthesized independently by esterification. In situ photoinduced crosslinking of the intercalated monomer and the PSU macromonomer in the silicate layers leads to nanocomposites that are formed by individually dispersing inorganic silica nanolayers in the polymer matrix. The morphology of the nanocomposites is investigated by XRD and TEM, which suggests the random dispersion of silicate layers in the PSU matrix. TGA results confirm that the thermal stability and char yield of PSU/MMT nanocomposites increases with the increase of clay loading. © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.Item Open Access Preparation of fluorinated methacrylate/clay nanocomposite via in-situ polymerization: characterization, structure, and properties(John Wiley and Sons Inc., 2016) Karamane, M.; Raihane, M.; Tasdelen, M. A.; Uyar, Tamer; Lahcini, M.; Ilsouk, M.; Yagci Y.Novel fluorinated coating containing well-dispersed silicate nanolayers is successfully produced via in-situ free radical polymerization of 2,2,2-trifluoroethyl methacrylate in the presence of vinylbenzyl-functionalized montmorillonite with different loading. The organic modification of sodium montmorillonite is achieved through an ion exchange reaction with triphenylvinylbenzylphosphonium chloride as surfactant prepared before use by reaction with vinylbenyl chloride and phosphine. The following in-situ polymerization in the presence of organomodified clay leads to fluorinated nanocomposites with of partially exfoliated and intercalated morphologies, as determined via XRD and TEM analysis. The nanoscale dispersion of clay layers is also evidenced by thermal analysis; a moderate decrease of the glass transition temperature about 2–8 °C compared to their virgin PMATRIF and an improvement of their thermal stability as evidenced by TGA. The wettability of the nanocomposite films is also studied by contact angle measurements with water. The incorporation of organomodified clays not only increases the hydrophobicity of the fluorinated polymers but also improves the surface properties of obtained nanocomposites. Compared the virgin homopolymer, the mechanical properties of the nanocomposites are reduced by addition of organomodifed clay at temperature from 30 to 60 °C, whereas this trend is gradually decreased at higher temperature.Item Open Access Simultaneous photoinduced electron transfer and photoinduced CuAAC processes for antibacterial thermosets(Elsevier, 2017) Oz, E.; Uyar, T.; Esen, H.; Tasdelen, M. A.A combination of simultaneous photoinduced electron transfer and photoinduced CuAAC processes enables the in-situ preparation of antibacterial thermosets containing silver nanoparticles (AgNPs) in one-pot. Upon photolysis of photoinitator, the generated radicals not only reduce Cu(II) into Cu(I) activator to catalyst the CuAAC click reaction, but also simultaneously generate AgNPs from AgNO3 through electron transfer reaction. Due to their reduction potentials difference, the polymer matrix is formed before the formation of AgNPs, assisting to eliminate the agglomeration of them. The thermoset structures are confirmed by FT-IR and solubility tests, whereas the presence of AgNPs is proven by transmission electron microscopy with energy dispersive X-ray system analyzer. The samples containing 5 and 10% AgNPs exhibited strong inhibition zones, where all kinds of bacteria (gram-positive (Staphylococcus Aureus) and gram-negative (Escherichia Coli)) were killed in the surrounding of the film samples.Item Open Access Synthesis and characterization of polysulfone / POSS hybrid networks by photoinduced crosslinking polymerization(Wiley, 2013) Dizman, C.; Uyar, Tamer; Tasdelen, M. A.; Yagci, Y.Crosslinked polysulfone/polyhedral oligomeric silsesquioxane (POSS) hybrid networks were synthesized in this work by photoinduced copolymerization of polysulfone dimethacrylate (PSU-DMA) and multifunctional POSS-methacrylamide (POSS-MAAm) with various feed ratios. The morphology of the nanocomposites was investigated by transmission electron microscopy (TEM), which suggests the random dispersion of POSS in the PSU matrix without macroscopic agglomeration. Thermogravimetric analysis results confirmed that the thermal stability and char yield of PSU-DMA/POSS-MAAm nanocomposites increased with the increase of POSS loading. Enhanced glass transition temperatures and storage modulus of the networks were observed to be higher than its precursor polymer. Polysulfone-based hybrid networks containing various POSS loadings are synthesized by photoinduced copolymerization of polysulfone dimethacrylate and multifunctional POSS-methacrylamide. While TEM results suggest the random dispersion of POSS in the polymer matrix, thermal and dynamic mechanical analyses clearly confirm the better thermal and mechanic behavior of hybrid networks. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.