Preparation of Polyurethane/Acrylic Hybrid Nanoparticles via a Miniemulsion Polymerization Process

Nanosized polyurethane/poly(n-butyl methacrylate) (PU/PBMA) hybrid latex particles (∼50 nm) with various compositions were successfully prepared using a redox-initiated miniemulsion polymerization process. Studies were carried out on the miscibility of PU prepolymer and BMA monomer, PU/BMA droplet formation, and polymerization kinetics. This process provides a new method to synthesize nanosize hybrid latex particles using a relatively small amount of surfactant. A suitable chain extension process was developed, where a hydrophobic chain extender was used to introduce intraparticle cross-linking while maintaining the original small particle size of the nanosize PU/PBMA hybrid latexes. The ratio of PU to BMA, the amount of grafting agent (hydroxyethyl methacrylate; HEMA), and the presence of the hydrophobic chain extender have little influence on the particle size of the final latexes compared to the seeded emulsion polymerization processes. This illustrates the advantage of this process, whereby the final particle size is less sensitive to the composition and amount of cross-linking agent or chain extender.