Development of amino functionalized POSS based (3-Glycidoxypropyl)trimethoxysilane hybrid sol-gel coatings for aircraft applications

Varan, Dilara Çisel
An amino functionalized and 50 percent amphiphilic polyhedral oligomeric silsesquioxane (POSS) based (3-Glycidoxypropyl)trimethoxysilane (GPTMS) sol-gel reaction was carried out under extreme basic conditions. Amount of POSS per 1 mol of GPTMS was varied at molar ratios of 0.2, 0.4, and 0.6. The sol-gel product was coated on the aluminium 2024 alloy samples with immersion technique and thermally treated to improve corrosion resistance of the alloy. Influence of aging durations (1, 3, and 6 days) on the sol-gel reactions and polymerization of the coating layer were investigated using Fourier Transform Infrared (FTIR) spectroscopy. Thermal properties of the cured samples were analyzed by Differential Scanning Calorimetry (DSC) measurements and Thermo-mechanical analyzer (TMA). Surface properties and corrosion performance of the coatings were tested using contact angle measurement and Electrochemical Impedance Spectroscopy (EIS) techniques, respectively. A 0.6 mole amino functionalized POSS incorporated, and 6 days aged GPTMS revealed better corrosion resistance and hydrophobic features.


Development of pH Sensitive Alginate/Gum Tragacanth Based Hydrogels for Oral Insulin Delivery
Cikrikci, Sevil; Mert, Behiç; Öztop, Halil Mecit (2018-11-07)
Insulin entrapped alginate-gum tragacanth (ALG-GT) hydrogels at different ALG replacement ratios (100, 75, 50, 25) were prepared through an ionotropic gelation method, followed by chitosan (CH) polyelectrolyte complexation. A mild gelation process without the use of harsh chemicals was proposed to improve insulin efficiency. Retention of almost the full amount of entrapped insulin in a simulated gastric environment and sustained insulin release in simulated intestinal buffer indicated the pH sensitivity of ...
Covalent immobilization of invertase on chemically activated poly (styrene-2-hydroxyethyl methacrylate) microbeads
A carrier for invertase enzyme was synthesized from styrene (S) and 2- hydroxyethyl methacrylate (HEMA) in the form of microbeads. These poly (styrene-2-hydroxyethyl methacrylate), P(S-HEMA) microbeads were activated by epichlorohydrin (ECH) treatment for covalent immobilization. The free and immobilized invertase were assayed in the hydrolysis of sucrose to glucose, and the obtained results were compared. The optimum pH was 4.5 for free and 5.5 for immobilized invertase. The optimum temperature of invertas...
Optimization of ethanol-water extraction of lignans from flaxseed
Zhang, Zhen-Shan; Li, Dong; Wang, Li-Jun; Özkan, Necati; Chen, Xiao Dong; Mao, Zhi-Huai; Yang, Hong-Zhi (2007-10-01)
The optimal conditions for the extraction of lignans from flaxseed were determined. A second-order regression for rotation-orthogonal composite design was used to investigate the effects of three independent variables, namely ethanol concentration (%), extraction temperature (degrees C, and extraction time (h) on the response, the acquired ratio of lignans. The independent variables were coded at five levels and their actual values selected on the basis of results of single-factor experiment. The second-ord...
Development of Silicalite/Glucose Oxidase-Based Biosensor and Its Application for Glucose Determination in Juices and Nectars
Dudchenko, Oleksandr Ye; Pyeshkova, Viktoriya M.; Soldatkin, Oleksandr O.; Akata Kurç, Burcu; Kasap, Berna O.; Soldatkin, Alexey P.; Dzyadevych, Sergei V. (2016-02-03)
The application of silicalite for improvement of enzyme adsorption on new stainless steel electrodes is reported. Glucose oxidase (GOx) was immobilized by two methods: cross-linking by glutaraldehyde (GOx-GA) and cross-linking by glutaraldehyde along with GOx adsorption on silicalite-modified electrode (SME) (GOx-SME-GA). The GOx-SME-GA biosensors were characterized by a four-to fivefold higher sensitivity than GOx-GA biosensor. It was concluded that silicalite together with GA sufficiently enhances enzyme ...
Immobilization of glucose oxidase and urease in hydrogel matrices
Gurel, I; Arica, MY; Hasırcı, Vasıf Nejat (1997-01-01)
Immobilization of glucose oxidase and urease in hydrogels of 2-hydroxyethyl methacrylae, and N-vinyl pyrrolidone (NVP) was achieved by irradiation (using UV kand gamma-rays). The effect of radiation on entrapment efficiencies, retention of activities and swelling rates was obtained. To optimize the system, duration of exposure, reaction temperature, co-monomer concentrations, initiator and cross linker compositions were varied. The repeated reusability of the generated products was also tested. It was found...
Citation Formats
D. Ç. Varan, “Development of amino functionalized POSS based (3-Glycidoxypropyl)trimethoxysilane hybrid sol-gel coatings for aircraft applications,” M.S. - Master of Science, Middle East Technical University, 2021.