Effects of sulfonated polyol on the properties of the resultant aqueous polyurethane dispersions

A polyol containing long sulfonated side chain, designated as PESS, was used to prepare aqueous polyurethane (PU) dispersions through the prepolymer mixing process in this study. The effects of this sulfonated polyol on the properties of the resultant waterborne polyurethanes (WPUs) were studied. Structures and properties of the WPUs were examined by FTIR, GPC, particle sizer, viscometer, TGA, DMA, DSC, tensile tester and surface resistance meter. When the content of total hydrophilic groups (i.e. sodium sulfonate group of PESS and quaternary ammonium carboxylate group of neutralized dimethylol propionic acid, DMPA) remains unchanged, the WPU dispersion with higher PESS content possesses higher average particle diameter and film decomposition temperature due to its higher average molecular weight (Mw). The WPU with higher PESS content possesses higher dispersion viscosity and film ionic conductivity due to the higher dissociation degree or electrostatic interaction of sodium sulfonate groups than quaternary ammonium carboxylate groups. PESS enhances the antistatic property of the WPU films, which can be used in electronic, wrapping, and coating industries. Moreover, the WPU film with higher PESS content exhibits lower modulus but higher elongation at break due to the lower hard segment content. The glass transition temperature of these amorphous films is at about −45 °C, irrespective of the PESS/DMPA ratio and hydrophilic group content (HGC).