High biobased content waterborne latexes stabilized with casein

Abstract

Growing environmental regulations are enforcing the synthesis of sustainable and ecofriendly materials. While waterborne processes, as emulsion polymerization, allow producing polymeric materials with low solvents emission, the reduction of their carbon footprint can be achieved by replacing petroleum-derived raw materials by biobased reagents. In this scenario, this work aims to synthesize high biobased content waterborne latexes by emulsion polymerization of two partially biobased commercial monomers (2-octyl acrylate, OA, and isobornyl methacrylate, IBOMA) in presence of previously methacrylated casein (bovine milk protein), which acts as a surfmer (i.e., an emulsifier capable of being radically polymerized). The kinetic study of the emulsion polymerization of OA and IBOMA allows optimizing the formulation, thus resulting that the incorporation of a low fraction of a more water soluble monomer is required to reach acceptable polymerization rates and high monomer conversion. The as-obtained films show promising performance in terms of their mechanical properties, resistance to solvents and biodegradability in organic compost, which could pave the way for the synthesis of high biobased (>75%) content binders for waterborne coatings.