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  • Küçük Resim
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    Autoxidized Oleic Acid Bifunctional Macro Peroxide Initiators for Free Radical and Condensation Polymerization. Synthesis and Characterization of Multiblock Copolymers
    (Springer, 2019) Ayyildiz, Elif; Eren, Melike; Canbay, Hale Secilmis; Ashby, Richard D.; Hazer, Baki
    Autoxidation of unsaturated fatty acids gives fatty acid macroperoxide initiators containing two functionalities which can lead to free radical and condensation polymerizations in a single pot. The oleic acid macroperoxide initiator obtained by ecofriendly autoxidation (Pole4m) was used in both the free radical polymerization of styrene and the condensation polymerization with amine-terminated polyethylene glycol (PEGNH2) to obtain triblock branched graft copolymers. The narrow molar masses of the poly oleic acid-g-styrene (PoleS) and poly oleic acid-g-styrene-g-PEG (PoSG) graft copolymers were successfully obtained. The inclusion of oleic acid decreased the glass transition temperature of the polystyrene segment because of the plasticizing effect of oleic acid. In addition, a mechanical property of the copolymer was improved when compared with the pure PS. Structural characterization, morphology of the fracture surface, micelle formation, thermal analysis and molar masses of the obtained products were also evaluated.
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    Ecofriendly Autoxidation of Castor Oil/Ricinoleic Acid. Multifunctional Macroperoxide Initiators for Multi Block/Graft Copolymers
    (Wiley, 2019) Eren, Melike; Hazer, Baki
    Ecofriendly autoxidation is a reaction of air oxygen with unsaturated organic molecules at room temperature. Castor oil and ricinoleic acid were ecofriendly autoxidized for 5 months to obtain castor oil macroperoxide with a Mn of 1935 g mol(-1) (Pcast5m) and the ricinoleic acid macroperoxide initiator (Prici5m) with a Mn of 1169 g mol(-1). Peroxide groups thermally initiated the free radical polymerization of methyl methacrylate (MMA), n-butyl methacrylate (nBMA), and styrene (S). Peroxide formation in the oxidized castor oil and ricinoleic acid was confirmed using iodometric analysis, elemental analysis, and differential scanning calorimetry technique. Peroxide decomposition in both macroperoxide initiators was observed at 166 degrees C for Prici5m and 170 degrees C for Pcast5m. Hydroxyl groups of Pcast5m were reacted with methacryloyl chloride to obtain methacrylated castor oil macroperoxide (PcastMA). The polymerization rates of the obtained macroinitiators were compared. The polymerization rate order is Pcast5m > Prici5m > PcastMA. Polymerization of styrene by PcastMA resulted in an increase in molar masses and an increase in the polymerization time while those of the styrene polymerization by Pcast5m and Prici5m remained constant. Carboxylic acid groups were reacted with amine-terminated polyethylene glycol (PEG), polydimethyl siloxane (PDMS), and polytetrahydrofuran (PTHF) while the hydroxyl functionality initiated the ring-opening polymerization of epsilon-caprolactone (CL). Prici-PEG-PMMA, Prici-PS-PDMS, Prici-PS-PTHF, Pcast-PS-PCL, Pcast-PCL-PMMA, and Pcast-PS-PnBMA multiblock copolymers were prepared and characterized using spectrometric, thermal, and stress-strain measurement techniques.
  • Küçük Resim
    Öğe
    Novel poly(3-hydroxy butyrate) macro RAFT agent. Synthesis and characterization of thermoresponsive block copolymers
    (2020) Hazer, Baki; Eren, Melike; Senemoğlu, Yetkin; Modjinou, Tina; Renard, Estelle; Langlois, Valérie
    A novel reversible addition fragmentation transfer (RAFT) agent based on the poly-3-hydroxy butyrate (PHB) with threehydroxyl groups (PHB-R2) and thermoresponsive amphiphilic block copolymers derived from N-isopropyl acryl amide(NIPAM) are described. Hydroxylated PHB is obtained by the reaction between PHB and diethanol amine (DEA) to preparehydroxylated PHB (PHB-DEA). It is then reacted with a RAFT agent, 2-(dodecylthiocarbonothioylthio)-2-methylpropionic acid(DDMAT). Hydroxyl ends of the hydroxylated PHB are capped with carboxylic acid end of the trithiocarbonate. The blockcopolymers obtained by the polymerization of NIPAM initiated by PHB-R2 were characterized by1H NMR and physicochem-ical techniques. PHB content in the obtained block copolymers is varying between 14 and 45 wt%. The thermo-responsive PHB-PNIPAM block copolymers show the lower critical solution temperature (LCST) 28 and 30 °C while LCSTof the pure PNIPAMis 32 °C.