Chain Transfer Activity of ω-Unsaturated Methacrylic Oligomers in Polymerizations of Methacrylic Monomers

Abstract

Chain transfer constants have been determined for an unsaturated methyl methacrylate trimer, CH2C(CO2Me)CH2[C(CO2CH3)(CH3)CH2]2H (MMA3), in polymerizations of methacrylate esters (ethyl, EMA; n-butyl, BMA; tert-butyl, tBMA; 2-ethylhexyl, EHMA) and for the analogous trimers of butyl methacrylate (BMA3) and methacrylic acid (MAA3), a hydroxyethyl methacrylate dimer (HEMA2), a hydroxyethyl methacrylate−methyl methacrylate−hydroxyethyl methacrylate trimer (HEMA−MMA−HEMA), and a HEMA macromonomer in methyl methacrylate (MMA) polymerization. These data have been assessed with reference to our previously reported data on chain transfer of MMA macromonomers in MMA polymerizations. The transfer constants (Ctr) for MMA3 in polymerizations of methyl, ethyl, n-butyl, tert-butyl, and 2-ethylhexyl methacrylate at 60 °C are similar (∼0.18). The Ctr of MAA3 (0.28 at 60 °C in 2-butanone solvent) in MMA polymerization is ca. 50% higher than that of MMA3 under similar conditions. Other trimers (BMA3, HEMA−MMA−HEMA) and a lo...