Effect of reaction temperatures on synthesis of poly(acrylamide-co-acrylic acid) grafted poly(styrene-co- methyl methacrylate) microgels

Abstract

Poly(acrylamide-co-acrylic acid) grafted poly(styrene-co-methyl methacrylate) was synthesized through simultaneous crosslinking and graft copolymerization in the presence of N,N’-methylenebisacrylamide crosslinker and potassium persulphate initiator. The main objective of this research was to produce a polymer microgel using emulsion polymerization process. Three different reaction temperatures, 60, 70 and 80 °C were used for the polymerization process. The chemical structure and the morphology of the polymer microgel were characterized using an attenuated total reflectance-Fourier transform infrared (ATR-FTIR) and scanning electron microscopy (SEM), respectively. Total solid content, water absorption and gel content were also analyzed. ATR-FTIR spectra of prepolymerization sample and microgel showed the appearance of a new peak in the range of 2800 - 2950 cm-1 and also a peak loss in the range of 970 - 1000 cm-1 after the polymerization process. SEM showed the surface formation of spherical microgel of around 100 to 600 nanometers. The total solid content (49.50 ± 1.43 %), water absorption (135.13 ± 1.90 %) and gel content (50.79 ± 1.23 %) at temperature 70 °C were higher which showed better colloidal properties compared to emulsion microgel at the temperature of 60 and 80 °C. Microgel produced at 60 °C polymerization temperature was used to coat two types of substrate, stainless steel and polymethyl methacrylate (plexiglass), however the coating was cracked and detached from the substrate after it dried. This microgel is suggested to be used as a coating for future study.