Synthesis and characterization of temperature responsive acrylamide based new generation polymers by living polymerization

Most of the studies performed about temperature responsive polymers so far are based on N-isopropylacrylamide (NIPAm). In this study, N-(3-methoxypropyl) acrylamide, N-(3-ethoxypropyl) acrylamide, N-cyclopropyl acrylamide, N-(2-methoxyethyl) acrylamide monomers which polymerizations have not been widely studied by the ATRP method before were synthesized by a nucleophilic substitution reaction of acryloyl chloride and structural characterizations were performed by using FT-IR and 1H-NMR. Polymers which are thermoresponsive, soluble in water or organic solvents, linear, having different molecular weights were synthesized by using the ATRP method from the synthesized monomers. Molecular weight and structural characterizations of the synthesized polymers were performed using GPC and 1H-NMR methods. It was observed that ATRP of monomers carried out in aqueous media resulted with reaction yields over 90% when the [I] / [CuBr] / [HMTETA], initiator – catalyst – ligand system was used with ratios 1 / 1 / 3 respectively. It was observed that the polydispersity values of the polymers are below 1.50, which is one of the criteria for controlled polymerization. However, it was observed that the Mn values estimated by the 1H-NMR method which is known as having relatively high accuracy, were high and do not agree with the theoretical Mn values. Cross-checks were performed with devices and methods having different configurations in terms of column, eluent, solvent, flow rate and detector in the molecular weight characterization of the obtained polymers by GPC. Although same polymer was analysed, high deviations was observed in the obtained results depending on the changes in device configurations and the working conditions. As an example, Mn value of poly[N-(3-ethoxypropyl) acrylamide] polymer, which was estimated as 35200 g/mol by 1H-NMR, was analysed by various GPC methods which details are given in the study as 13200 g/mol by GPCTHF 54800 g/mol by GPCDMF-2 and 96400 g/mol by GPCLS method. Mw/Mn polydispersity values were calculated as 1.42 – 1.38 and 1.32, respectively.