Browsing by Author "Aykac, Cengiz"

Now showing 1 - 5 of 5

One-Step Synthesis and Characterization of the Block-Graft Terpolymer Via Simultaneous Atom Transfer Radical Polymerization (Atrp) and Ring-Opening Polymerization (Rop) Techniques
(indian Acad Sciences, 2022) Goktas, Melahat; Aykac, Cengiz; Ozturk, Temel
In this study, we evaluated cooccurring ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP) for simultaneous one-step synthesis of the block-graft terpolymer of E-caprolactone and methyl methacrylate using polyepichlorohydrin (PECH) macroinitiator. For this purpose, the block-graft terpolymer was synthesized by ROP of a lactone and ATRP of a vinyl monomer using the PECH macroinitiator, which is an initiator suitable for both ROP and ATRP in one step. Spectral and chromatographic analyzes prove that the strategy used is successful in the simultaneous one-step preparation of the block-graft terpolymer with controlled molecular weights and narrow distributions.
Synthesis and Characterization of a Brush Type Graft Copolymer Via Raft and "click" Chemistry Methods
(Springer, 2023) Goktas, Melahat; Aykac, Cengiz; Ozturk, Temel
In this study, well-known poly(4-vinylbenzyl-g-ethylene glycol) [P(4-VB-g-EG)] brush type graft copolymer was synthesized by recycling additive/fragmentation chain transfer (RAFT) polymerization and a "click" chemistry method. In the first step, a RAFT agent (CTA) was synthesized for this purpose by the reaction of 2-(2-chloro ethoxy) ethanol and potassium ethyl xanthogenate salt. In the second step, poly(4-vinylbenzyl chloride) [P(4-VBC)] was synthesized by performing RAFT polymerization of 4-vinylbenzyl chloride using a RAFT initiator. In the third step, poly(4-vinylbenzyl-N-3) [P(4-VB-N-3)] was produced by a reaction that synthesized P(4-VBC)] and NaN3. In addition, PEG-propargyl (alkyne-terminated-PEG) was obtained by the reaction between polyethylene glycol (PEG-3000) and propargyl chloride. In the last step, poly(4-VB-g-EG) brush type graft copolymer was obtained by the reaction of PEG-propargyl and poly(4-VB-N-3) via the "click" chemistry method. The synthesized products were characterized utilizing various spectroscopic methods. The DSC result showed that the glass transition temperature value of the brush type graft copolymer was 30 & DEG;C, different from that of the homopolymer. The SEM analysis demonstrated that the surface morphology of the homopolymer and brush type graft copolymers differed. The fact that the brush type graft copolymer has two different decomposition temperatures such as 220 & DEG;C and 410 & DEG;C has been proven by TGA analysis.
Synthesis and Characterization of Block Copolymer: Thermal and Morphological Properties of Sio2-Filled Block Copolymer Nanocomposites
(Springer, 2023) Goktas, Melahat; Aykac, Cengiz; Akinay, Yuksel
With the development of nanotechnology, the production and use of the nanocomposites has been increased. Polymer nanocomposites are among the most widely used nanocomposites. In this study, block copolymer and block copolymer-based polymer nanocomposites were synthesized and evaluated. For this purpose; firstly, poly(beta-butyrolactone)-b-poly(methyl methacrylate) [P(BL-b-MMA)] block copolymers were prepared simultaneously in one-pot by recycling additive/fragmentation chain transfer (RAFT) and ring-opening (ROP) polymerizations using a novel bifunctional RAFT-ROP agent which synthesized by chemical reaction with 3-bromo-1-propanol and potassium ethyl xanthate. Secondly, for the preparation of polymer nanocomposite, SiO2 nanoparticles were added to the prepared block copolymer with a rate of 3 wt% both during the polymerization stage and after the polymerization stage. The synthesized RAFT-ROP agent, block copolymer, and polymer nanocomposites were characterized using spectroscopic methods. The effect of copolymerization reaction conditions on molecular weight and molecular weight distribution (dispersity) was investigated. In one-pot copolymerization processes, relatively high weight copolymers were obtained by changing the copolymerization conditions due to the active centers in the copolymerization environment. The thermal characterization showed that the glass transition temperature of the block copolymer decreases with the addition of SiO2 during the polymerization stage and increases with the addition of SiO2 after the polymerization stage. SEM surface morphologies showed that block copolymer and polymer nanocomposites morphology is different from each other. The difference can be explained by the good dispersion of the block copolymer and SiO2 nanoparticles within each other.
Synthesis of Block-Brush Terpolymer Via One-Step Raft-Rop and Grafting To "click" Chemistry Methods
(Springer, 2025) Goktas, Melahat; Aykac, Cengiz
In this contribution, well-defined poly(epsilon-caprolactone-b-4-vinylbenzyl-g-ethyleneglycol) [poly(epsilon-CL-b-VB-g-EG)] block-brush terpolymer was prepared via reversible addition/fragmentation chain transfer (RAFT), ring-opening polymerization (ROP) and grafting to "click" chemistry methods. For this purpose, in the first part, a RAFT agent was obtained by the reaction of 3-chloro-1-propanol and ethylxanthic acid potassium salt for the one-step RAFT-ROP polymerization. In the second part, the poly(epsilon-caprolactone-b-4-vinyl benzyl chloride) [poly(epsilon-CL-b-VBC)] block copolymer was prepared by RAFT polymerization of 4-vinyl benzyl chloride, and ROP of epsilon-caprolactone in the presence of RAFT agent in the one-step. In the third part, the poly(epsilon-caprolactone-b-4-vinyl benzyl-N3) (azide-terminated) was obtained from reaction of the poly(epsilon-CL-b-VBC) block copolymer and NaN3. Finally, the poly(epsilon-CL-b-VB-g-EG) block-brush terpolymer was prepared from the reaction PEG-propargyl, which obtained by the reaction of polyethylene glycol (PEG-3000) with propargyl chloride, and poly(epsilon-CL-b-VB-N3) via the grafting to "click" chemistry method. The structure of the final products was characterized by methods such as GPC, 1H-NMR, FT-IR, DSC, and SEM.
Synthesis of Poly(styrene)-G Acid) Graft Copolymers Via Reversible Addition/Fragmentation Transfer (Raft) Polymerization Using a Poly Oleic Acid Macro-Raft Agent
(Springer, 2024) Goktas, Melahat; Aykac, Cengiz; Hazer, Baki; Ashby, Richard D.
In this study, a new polymeric oleic acid-derived macro addition/fragmentation transfer agent was utilized to produce a poly(styrene)-g-poly(oleic acid) graft copolymer. The double bond of oleic acid was initially saturated with bromine and the condensation polymerization between the carboxylic acid and the bromide resulted in polyoleic acid with pendant bromide groups. Xanthate groups were exchanged with the bromide groups to obtain the poly(oleic acid) macro RAFT agent (Pole-Xa). Poly(styrene)-g-poly(oleic acid) (PS-g-Pole) graft copolymers were synthesized via reversible addition fragmentation transfer (RAFT) polymerization of styrene and the reaction was evaluated in view of the polymerization kinetics. The effects of polymerization temperature and reaction time on graft copolymer yield, conversion and molecular weight were investigated. In the RAFT polymerization of styrene, the rate constant (k) was found to be 1.83 x 10(-3) L/mol/dk and 7.27 x 10(-4) L/mol/dk for the polymerization temperatures of 80 and 90 degrees C, respectively. The structural characteristics and thermal properties of the obtained products were characterized using FT-IR, H-1-NMR, GPC, TGA, DSC and SEM-EDX.