• SEMA ALLI

      Articles written in Journal of Chemical Sciences

    • Synthesis and characterization of poly(linoleic-g-e-caprolactone) graft copolymers via ‘‘click’’ reaction and ring-opening polymerization

      SEMA ALLI

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      Linoleic acid modified with auto-oxidation, hydroxylation, bromination and azidation was usedto synthesis graft copolymers using Ѡ-alkyne-terminated poly(Ɛ-caprolactone) (alk-PCLs) via ‘‘click’’ reaction.In the first step, the polymeric linoleic acid (PLina) as macroinitiator was obtained by the autoxidation oflinoleic acid. Hydroxylation of the PLina was then carried out using diethanolamine to produce hydroxylatedpolymeric linoleic acid (PLina-OH). The PLina-OH was chemically modified with 2-bromopropionyl bromideto obtain bromo-functionalized polymeric linoleic acid (PLina-Br). This macroinitiator was thenmodified with sodium azide, resulting in azide polymeric linoleic acid (PLina-N3). In a parallel process, Ѡ alkyne-terminated poly(Ɛ-caprolactone) (alk-PCLs) were prepared via ROP of the Ɛ-caprolactone monomer inthe presence of propiolic acid, 3-butyn-1-ol, 5-hexynoic acid, and propargyl alcohol as the precursors andtin(II) 2-ethyl hexanoate (Sn(Oct)22) as the catalyst. These preliminary steps involved the synthesis of azideand alkyne compounds capable of being linked together via the alkyne-azide cycloaddition reaction catalyzedby copper (Cu(I)), which led to poly(linoleic acid)-g-poly(Ɛ-caprolactone) (PLina-g-PCL). The obtainedpolymers were characterized by proton nuclear magnetic resonance (1H NMR), Fourier-transform infrared(FTIR), differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA) and elemental analysis.

    • Synthesis and physicochemical characterization of PMMA and PNIPAM based block copolymers by using PEG based macro RAFT agents

      YETKIN SENEMOGLU BAKI HAZER HULYA ARSLAN ABDULKADIR ALLI SEMA ALLI SADI SEN

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      Polyethylene glycol (PEG) based macro-RAFT agents were synthesized by the condensation reaction of PEG (Mn: 2000 Da and 8000 Da) with the carboxylic acid functionalized trithiocarbonate [S-Dodecyl-S′-(a,a′-dimethyl-a′′-acetic acid) tritiocarbonate (DDMAT)] using dicyclohexylcarbodiimide(DCC)/4-(dimethylamino) pyridine (DMAP) as catalyst at room temperature. Then, N-isopropylacrylamide(NIPAM) and methyl methacrylate (MMA) monomers were polymerized, respectively, using synthesizednew macro-RAFT agents and N, N′-azo bis isobutyronitrile (AIBN) as the initiator. In all RAFT polymerizations, dispersity values were found in the range of 1.04 to 1.47, which showed that RAFT polymerizationwas applied successfully. The synthesized polymers were characterized using Fourier Transform Infrared Spectroscopy (FTIR), Proton Nuclear Magnetic Resonance Spectroscopy (1H-NMR), Gel Permeation Chromatography (GPC) and Differential Scanning Calorimetry (DSC) techniques. The fractured surfaceimages of PEG-b-PMMA block copolymers were obtained by Scanning Electron Microscopy (SEM). SEMimages PEG-b-PMMA block copolymers have shown that the copolymers have a microporous structure. Inaddition, the swelling ratios and LCST values of the PEG-b-PNIPAM block copolymers were measuredwhich were found to be very high. The lower critical temperature values of the copolymers are closer to thatof the PNIPAM homopolymer, 32°C, indicating its usability in drug delivery systems.

      Macro-RAFT agents were successfully synthesized in high yield by reacting S-dodecyl-S′-(α,α′-dimethyl-α″-acetic acid) tritiocarbonate (DDMAT) (R-2) with polyethylene glycols (Mn: 2000 Da and 8000 Da, respectively). Subsequently, the monomers methyl methacrylate (MMA) and N-isopropylacrylamide (NIPAM) were polymerized respectively using synthesized macro-RAFT agents. SEM images of PEG-b-PMMA block copolymers have shown that the copolymers have a microporous structure. The critical temperature values of the PEG-b-PNIPAM block copolymers are closer to that of the PNIPAM homopolymer, 32 °C, indicating their usability in drug delivery systems.

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