Polyurethane dispersions (PUDs) with solid content above 50% were synthesized by using polyether diol containing sulfonate (SPPG) as hydrophilic monomer in the soft segment

dimethylol propionic acid (DMPA) as hydrophilic monomer in the hard segment

poly(hexamethylene neopentylene adipate) (PHNA)

isophorone diisocyanate (IPDI)

hexamethylene diisocyanate (HDI) and piperazine by the acetone method. The results showed that the zeta potentials of PUDs were between -52 mV and -72 mV and the PUDs displayed excellent stabilization. The average particle sizes decreased

the particle size distributions narrowed and the viscosity increased when the hydrophilic group content and the mole ratio of HDI to IPDI increased. The viscosity evidently decreased when the mole ratio of —SO3Na to —COOH decreased as a volume fraction of small particles between 21% and 28%.TEM analysis showed polydispersity and different sizes of the spherical particles. Dynamic mechanical analysis showed compatibility of soft and hard segments of the PUDs and a low glass transition temperature of the PUD film.