Mechanical properties of pH-responsive poly(2-hydroxyethyl methacrylate/methacrylic acid) microgels prepared by inverse microemulsion polymerization

摘要

The structure and mechanical properties of monodisperse pH-responsive poly(2-hydroxyethyl methacry-late/methacrylic acid) (poly(HEMA/MAA)) microgels prepared by inverse microemulsion polymerization were systematically investigated. To facilitate the polymerization, the inverse microemulsion systems were first optimized by generating relevant pseudo-three-component phase diagrams. The reactivity ratios of HEMA(r_1 = 1.001 ±0.064) and MAA (r_2 = 0.318 ±0.035) determined by titration method suggested that PHEMA segments preferred to be localized in the core of the synthesized poly(HEMA/MAA)) microgels. The mechanical property studies of the microscopic poly(HEMA/MAA)) microgels from oscillation rheometry revealed that microgel composition, concentration and pH could significantly alter the elastic modulus (G′), and a maximum averaged elastic modulus (G′_(ave)) value of about 8.2 × 10~3 Pa was obtained.