Effect of sodium hydroxide solution as polymerization solvent and activator on structural, mechanical and antibacterial properties of PNIPAAm and P(NIPAAm–clay) hydrogels

Poly(N-isopropylacrylamide) (PNIPAAm) and its composite hydrogels were synthesized by free-radical polymerizations in NaOH solutions (0.1, 0.2 N). Laponite (LP), Montmorillonite (MMT) and ODA(octadecylamine)-MMT were used as inorganic multicrosslinkers while BIS was chosen as conventional crosslinker. All polymerizations were initiated with KPS alone. The effects of two different concentrations of NaOH-KPS redox pair and long reaction times (1w and 2w) at 25°C on structural and mechanical properties, antibacterial and haemolytic activities of the modified hydrogels were studied by conductometric titrations, FTIR, XRD, EDX, compression, inhibition zone and haemolysis tests. Their homogenities, compressive moduli at 37°C, antibacterial activities and blood compatibilities increased with increasing reaction time and NaOH concentration. POLYM. COMPOS., 39:E386–E406, 2018.