Synthesis and characterization of novel water-based poly(urethane-imide) nanodispersions

Poly(urethane-imide) nanodispersions were synthesized in four steps, as described below. In the first step, polyurethane prepolymer was prepared by the reaction of hexamethylene diisocyanate and polypropylene glycol in the presence of a catalytic amount of dibutyltin dilaurate. In the second step, poly(urethane-imide) prepolymer was prepared by the reaction of synthesized polyurethane prepolymer in the first step with pyromellitic dianhydride in dimethylformamide. In the third step, the prepared poly(urethane-imide) (PUI) reacted with 2,2-bis (hydroxymethyl) propionic acid, and the reaction completed in the last step which involved neutralization and dispersion in water, where acidic poly(urethane-imide) was neutralized by the addition of triethylamine. The prepared poly(urethane-imide) dispersions were characterized by fourier transform infrared spectrometry, proton nuclear magnetic resonance spectroscopy (¹HNMR), thermogravimetric analysis, and dynamic laser scattering. A series of PUI dispersions with 30 wt% solid content, viscosities of 9 ± 1 cps, and particle sizes of 78–133 nm range were prepared and characterized.