Well-Controlled Emulsion Polymerization of Methyl Methacrylate Using (Hg,Cd)-Diphenylcarbazone Catalysts: An attempt to Create Hg-free, Nontoxic, γ-Radiation and thermal Stable Films

Abstract

In this work, a procedure for synthesis of Hg and Cd-free PMMA films via emulsion polymerization using different concentrations (0.000025 - 0.00025 g mol/L) of Hg and Cd-diphenylcarbazone complexes (Hg(or Cd)DPC) as a catalytic chain transferring agent was reported. The extraction of either HgDPC or CdDPC from resultants polymers was confirmed using UV-Vis spectrophotometry and the neat polymers presented no cytotoxicity to human Hep G2 Cells. Well dispersity of PMMA (DPI of ca. 1.3) and the optimal performance in MMA polymerization was achieved using 0.00020 g mol/L HgDPC, which exhibited a PMMA yield of ca. 98%. Thermal behavior studies proved that PMMA films became highly thermally stable suggested as due to the elimination of head-to-head growing PMMA chains and disproportionation mechanistic steps. Therefore, the degradation process is mainly due to the random main chain scission, which on turn demonstrated a positive impact on its melting, decomposition and, glass transition (Tg) temperatures where, Tg of PMMA samples understudy increased in the following order: blank(60°C)˂CdDPC(69°C)˂HgDPC(84°C).The radiation shields and mechanical properties of PMMA films were also studied to evaluate the anti-radiation affinity of these complexes where, a tensile strength of 85.0 MPa of resultant PMMA using HgDPC was acquired.