Investigation of the effect of the end groups and various polymeric blocks on the behaviour of thermal sensitive polymers

In this study poly(N-isopropylacrylamide) (NIPA) polymers ended hyroxyl and epoxide were synthesized by atom transfer radical polymerization (ATRP) method using 2-hydroxyethyl 2-chloropropionate and glycidyl 2-chloropropionate as the initiators. End group in epoxide terminated polymer was reacted with tris(hydroxymethyl) aminomethane (TRİZMA) so the end group of polymer was gained highly hydrophilic property. Diblock copolymers were synthesized with ethyl methacrylate (EMA), N,N-dimethylacrylamide (DMA) and 2-hydroxy-propyl methacrylate (HPMA) monomers by ATRP method using 2-hydroxyethyl terminated PNIPA polymer as macroinitiator. PNIPA-b-PHPMA-g-PCL graft copolymer was synthesized with PNIPA-b-PHPMA by ring opening polymerization of ε-caprolactone. In addition, two type ABC triblock copolymer were synthesized with EMA and benzylmethacrylate (BMA) monomers with PNIPA-b-PDMA diblock copolymer as macroinitiator by ATRP method. In another part of the study, multiblock PNIPA copolymers were synthesized by free radical polymerization method. For this purpose copolymers were synthesized with highly ratio of NIPA monomer and lower and different ratio (% 20, 10, 5) of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS), N-[3(dimethylaminopropyl)]methacrylamide (DMAPMA), vinylbenzyltrimethylammonium chloride (VBC) and N-[tris(hydroxymethyl)methyl] acrylamide (THMMA) monomers. In addition, graft copolymer of P(NIPA-co-THMMA) was synthesized by ring-opening polymerization of glycidol. Structural characterization of the polymers was performed with FT-IR, 1H and 13C-NMR techniques. The thermal behavior of the polymers was examined by DSC and TGA, and the results were compared with each other. Dielectric behavior of polymers was investigated as a function of temperature and frequency and associated with their structures. LCST of end-functionalized PNIPA homopolymers (mono- hydroxyl-terminated, epoxide- hydroxyl-terminated, three hydroxyl-terminated), all the diblock, triblock, and multiblock copolymers were determined by turbidimeter, UV-visible spectrophotometer and viscosimetry. Differences in LCST values of polymers were associated with their structures and discussed.