Novel acrylic hybrids emulsion(PAH) with 98.8 mgKOH/g hydroxyl value and 45.0%(wt) solids content were designed and synthesized by semi-batch seeded emulsion polymerization with β-hydroxyethyl methacrylate (HEMA) as a hydroxy monomer, which polar monomers were multi-stages added and carboxyl groups were neutralized during the polymerization process. TEM photos show that PAHs were composed of two kinds of emulsion particles including one covered with carboxy groups(P1) and the other carrying hydroxy groups(P2). Nano-granularity analysis show that average diameters of the PAHs were smaller and its particle distributions were much broader than those of the common hydroxy polyacrylate emulsions (HPAE). Two component waterborne polyurethane coatings (2K-WPU) were prepared with PAH, and the properties of 2K-WPU films indicated that the optimal mass ratio of carboxy / hydroxy groups in P1 and P2 were 1：0 and 1：3, respectively. The FT-IR spectra show that the reactions between NCO and OH in 2K-WPU films were completely finished in 3 days. AFM pictures indicated that the surface of 2K-WPU cured films were excellent.
