Copolymerization of butyl acrylate with methyl methacrylate in a bubble column reactor and the use of copolymer in corrosion protection

In this paper, copolymerization of methyl methacrylate (MMA) with n-butyl acrylate (BA) in a bubble column reactor using benzoyl peroxide as free radical initiator, at a temperature over 85 °C, is presented. This mode of copolymerization keeps an inert atmosphere throughout the entire reaction and contributes to proper mixing of the monomers. Higher pressure of the bubbling ensures the faster contact of the species, and a higher conversion was obtained in a shorter reaction time. The conversion of monomer at 124 Pa after 210 min is total, which is particularly noteworthy due to the absence of residual monomer that represents hazardous compounds, with negative impact upon employees and end-user safety. Higher conversions are obtained at 96 °C, 124 Pa nitrogen bubble pressure, 60/40% moles monomer ratio BA/MMA and 2% POB. The molar mass Mw, Mn and PDI decrease with the increase in temperature quite linearly. In the absence of nitrogen bubbling, the copolymer composition is approximately the same as in the feeding mixture. The corrosion protection efficiency of steel painted with these acrylic coatings was carried out by means of OCP and potentiodynamic polarization testing and electrochemical impedance spectroscopy (EIS).