Acrylic Latexes from Plant Oil-Based Monomers: Innovative Approach for Waterborne Facade Paints

Abstract

In this study, partially bio-based acrylic latexes composed of acrylated plant-oil-derived monomers from rapeseed (RO), sunflower (SO), linseed (LO), and camelina (CO) oils were synthesized via emulsion polymerization and evaluated as binders for waterborne facade coatings. In these latexes, the plant oil-based monomer constituted 25 wt.% of the total monomer feed and was copolymerized with commercial acrylic monomers. The influence of plant oil origin and emulsifier type (conventional vs polymerizable) on latex characteristics, polymer architecture, and coating performance was systematically investigated. All bio-based latexes exhibited good colloidal stability (particle diameter 120–180 nm; ζ-potential −40 to −48 mV) and low minimum film-forming temperatures (≤0 °C). Asymmetric flow field flow fractionation coupled with a multi-angle light scattering revealed extensive gel formation (75–95%) due to multi-acrylated plant oil-derived components (primarily linoleic and linolenic fatty acid derivatives) possessing inherent crosslinking potential, with CO-derived systems showing the highest crosslink densities. At the same time, the fatty acid-derived segments contributed to an internal plasticization effect, demonstrating the ambivalent character of the plant oil-derived monomers that simultaneously promote network formation and film flexibility. This structural modification resulted in favorable coating performance. In non-pigmented films, the polymerizable emulsifier-based CO-derived system exhibited low water whitening (13.4%) and water uptake (13.5 wt.%), representing a sevenfold reduction relative to the reference system. In facade paints, the polymerizable emulsifier-based CO- and LO-derived systems showed excellent wet scrub resistance (≤2 μm thickness loss, class 1), improved adhesion (class 1), and superior color stability after accelerated weathering (ΔE* ≈ 0.54–0.72), outperforming the commercial benchmark (ΔE* = 1.06). These results demonstrate that the combination of highly unsaturated plant oil-derived monomers and polymerizable emulsifiers enables the design of high-performance, partially bio-based waterborne facade binders with enhanced water resistance and weathering durability.