Versatile Platform for Controlling Properties of Plant Oil-Based Latex Polymer Networks

A series of latexes from acrylic monomers (made from olive, soybean, linseed, and hydrogenated soybean oils), significantly different in terms of fatty acid unsaturation, were synthesized using miniemulsion copolymerization with styrene. The number-average molecular weight and the glass transition temperature of the resulting copolymers with high levels of biobased content (up to approximately 60 wt %) depend essentially on the amount of unsaturation (the number of double bonds in triglyceride fatty acid fragments of plant oil-based monomers) in the reaction feed. When plant oil-based latex films are oxidatively cured, the linear dependence of the cross-link density on reaction feed unsaturation is observed. Dynamic mechanical and pendulum hardness measurements indicate that the properties of the resulting plant oil-based polymer network are mainly determined by cross-link density. On the basis of the linear dependence of the cross-link density on monomer feed unsaturation, it can be concluded that the latex network formation and thermomechanical properties can be adjusted by simply combining various plant oil-based monomers at certain ratios ("given" unsaturations) in the reaction feed. Assuming a broad variety of plant/vegetable oils available for new monomers synthesis, this can be considered as a promising platform for controlling properties of plant oil-based latex polymer networks.