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.
Volume 134, 2022
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