Abstract
Vinyl monomers from eugenol (EBM) and guaiacol (GBM) were copolymerized in miniemulsion process with high oleic soybean oil-based (HOSBM) counterpart to yield latexes with higher biobased content. Fully renewable monomer feed yields a broad range of new emulsion polymers with the number-average molecular weight varying at 25,000-650,000 g/mol. Increasing GBM/EBM content in the reactive feed leads to increasing latex molecular weight due to the decreasing unsaturation degree (lower content of HOSBM). Monomer feed unsaturation effect found to be more pronounced for latexes from EBM and HOSBM, since GBM shows higher reactivity in free radical polymerization if compared to GBM. Presence of oil-derived unsaturated fragments in emulsion polymers provides an opportunity to crosslink latexes in a controlled way and adjust the resulting polymer networks mechanical properties. Biobased latexes from 25-90 wt.% of GBM/EBM and 10-75 wt.% of HOSBM were synthesized, characterized and tested in terms of thermomechanical properties of latex crosslinked films and coatings. It is demonstrated that characteristics of latex films and coatings are determined by nature and ratio of aliphatic oil residues of HOSBM and aromatic fragments of EBM/GBM in the macromolecular backbone. Incorporation of rigid fragments of GBM/EBM enhances Young's modulus of the films, whereas the soft plant oil-based units contribute to flexibility of films and coatings. All crosslinked latex films exhibited decent properties and performance in terms of hardness, impact resistance, as well as adhesion to the steel substrate. By combination of aliphatic fatty acid fragments of HOSBM with aromatic GBM/EBM structure, durable latexes can be synthesized with ability to balance thermomechanical properties of the latex polymer networks in a broad range.