Effect of Selected Comonomers on the Transition Temperature of Thermosensitive NIPA Derivatives Synthesized with an Anionic Initiator.

The present study evaluates the effect of the cationic initiator on the hydrodynamic diameter of copolymers of N -isopropylacrylamide nanogels synthesized via a surfactant-free precipitation polymerization at 70 °C in the presence of the cationic initiator 2,2'-azobis[2- methylpropionamidine] dihydrochloride. Three types of polymeric nanoparticles were synthesized using N, N '-methylenebisacrylamide as a crosslinker. The first batch was used as a reference. The second type of particles included a poly(ethylene glycol) methyl ether-acrylate monomer, while the third type used an N-tert -butylacrylamide comonomer. The hydrodynamic diameters of the synthesized particles were between 160 and 970 nm at 18 °C. The chemical composition and morphology of the synthesized co-polymeric nanoparticles were confirmed using infrared spectroscopy, nuclear magnetic resonance and scanning electron microscopy. The zeta potentials measured via dynamic light scattering were 20.0, 17.0, -0.1 mV for the three types, respectively. The volume phase transition temperature was between 22 and 41 °C. The polydispersity index of particles synthesized with N -tert-butylacrylamide varied depending on the measurement temperature.