Challenges to incorporate high contents of bio-based isobornyl methacrylate (IBOMA) into waterborne coatings

Emulsion polymerization of (meth)acrylic bio-based monomers is a promising method to obtain waterborne coatings with reduced carbon footprint. However, the high hydrophobicity of some bio-based monomers can hinder the straightforward incorporation of such monomers in waterborne dispersions. In this work, we explore the copolymerization of bio-based isobornyl methacrylate (IBOMA) with 2-octyl acrylate (2-OA) to produce latexes with >70 % bio-content suitable for coating applications. First, the homopolymerization of IBOMA is studied to gather more information on the emulsion polymerization of the monomer producing high Tg polymer with different surfactants. It is found that the batch emulsion homopolymerization of IBOMA is challenging due to coagulation during the polymerization, likely as a result of mass transport limitations due to the high hydrophobicity of IBOMA. Interestingly, stable dispersions are achieved when 5 % of the IBOMA is substituted by methyl methacrylate. The stability of the IBOMA/2-OA copolymer system is found to be dependent on both the IBOMA concentration in the copolymer and the solids content of the latex. Thus, we provide a stability map for IBOMA/2-OA copolymers with different compositions and solids contents showing the areas where stable and not-stable dispersions are obtained.