Route to co-acrylic modified alkyd resins via a controlled polymerization technique

Abstract

Acrylic modified alkyds were achieved from sequential polymerization of acrylic monomers in the presence of alkyd macro-RAFT agents. Macro-RAFT agents were reached by end-capping a soya-based alkyd with a carboxy-functional trithiocarbonate. The resulting material was then utilized as the RAFT chain transfer agent to affix acrylic blocks onto the alkyd backbone. Butyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate were the acrylic monomers used to achieve the acrylic blocks both individually and in combination. The resulting materials were characterized by various analytical techniques including size-exclusion chromatography (SEC), Fourier transform infrared (FTIR) spectroscopy, and nuclear magnetic resonance (NMR) spectroscopy. Size exclusion chromatography confirms the controlled nature of this approach to acrylated-alkyds and corroborates the NMR spectra that distinctly show the presence of acrylic blocks. Side reactions with the pendant fatty acids and the formation of homopolyacrylate are also distinguished from the analytical results, however, they are suppressed. Pseudo-first-order kinetics behavior and conversion versus molecular weight plots show that the RAFT-mediated reaction afforded a more controlled free radical process for the synthesis of acrylated-alkyd materials. Use of the alkyd macro-RAFT agent provided a new path to acrylated-alkyds that affords a more controlled way to tailor specific material properties.