Kimya

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Browsing Kimya by Author "Altuncu, Merve Seçkin."

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    (BIS) phosphonate functionalized polymeric materials for biomedical applications
    (Thesis (Ph.D.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2022., 2022) Altuncu, Merve Seçkin.; Avcı, Duygu.
    This work describes synthesis, characterization, and evaluation of (bis)phosphonate functionalized monomers, macromers and crosslinkers as well as their polymers and crosslinked networks for biomedical applications such as tissue engineering scaffolds, dental materials and targeted drug delivery. Various synthetic approaches were explored for incorporation of (bis)phosphonate functionality and tailoring of these materials’ properties such as degradation rate, mechanical moduli, mineralization ability, water solubility and hydroxyapatite affinity. In the first part, three novel phosphonate/phosphonic acid functionalized poly (β-amino ester) (PBAE) macromers with varying levels of hydophilicity were synthesized and homo- and copolymerized with poly(ethylene glycol) diacrylate (PEGDA) to fabricate networks with tunable degradation and mechanical properties. The second part reports synthesis of three novel phosphonic acid containing poly (amido amine) macromers and their homo- and copolymerization with 2- hydroxyethyl methacrylate to obtain hydrogels showing composition-dependent swelling, degradation and mineralization. In the third part, two different types of bisphosphonate/ bisphosphonic acid functional thermoresponsive polymers were synthesized (i) by copolymerization of three novel bisphosphonate functionalized acrylamide monomers containing different alkyl chains with N-isopropyl acrylamide, (ii) alendronate functionalization of a copolymer of NIPAM and 6- acrylamidohexanoic acid. In the last part, alendronate was incorporated into two carboxylic acid containing polymers (ibuprofen functionalized alkyl α-hydroxymethacrylate and 6- acrylamidohexanoic acid based polymers) via covalent and non- covalent interactions to enhance their hydroxyapatite affinity. The materials synthesized here have potential for (mostly bone-related) biomedical applications such as tissue engineering and targeted controlled drug delivery; and the methods can be used to fabricate more such materials, tailoring their properties to fit the desired application.
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    Synthesis of networks and interenetrating networks of maleated castor oil and epoxy resins
    (Thesis (M.S.) - Bogazici University. Institute for Graduate Studies in Science and Engineering, 2015., 2015.) Altuncu, Merve Seçkin.; Taylan, Ediz.; Küsefoğlu, Selim.
    In this study, castor oil is reacted with maleic anhydride to give maleated castor oil (COMA) which can be used as a biobased epoxy curing agent to enhance the problems of brittle structure of epoxy resins and can undergo free radical polymerization with reactive diluents to give interpenetrating networks which increase mechanical properties. The maleation of castor oil is carried out using the known method developed earlier by our research group with small modifications to increase maleation ratio and shorten the reaction time. Then, COMA is reacted with commercial epoxy resins Bisphenol A diglycidal ether (DGEBPA), Novolac epoxy resin, Heloxy 505 epoxy resin- through its carboxylic acid ends to give thermoset polymers. As a third step, the intact double bonds in polymer structure are polymerized free radically with styrene in the presence of an initiator, azobisisobutyronitrile (AIBN) to give a second interpenetrating network. Characterization of the products is done by IR spectroscopy only due to their crosslinked structure. IR spectra of the polymers are also used to decide the optimum ratio of stoichiometry of COMA/epoxy resin. Thermal stabilities of the samples are analyzed with TGA (Thermogravimetric Analysis). Mechanical properties are determined by surface hardness test by Shore A durameter and three point bending test using the home made instrument produced by our lab.