Preparation of waterborne polyurethanes based on the organic solvent-free process

A green waterborne polyurethane (WPU) was prepared based on an organic solvent-free process, using sodium 2,4-diaminobenzene-sulfonate (SDBS) as a chain extender. Water was only used to dissolve the solid reactants and reduce the viscosity, obtaining the homogenized reaction mixture. Characterization results showed that this green WPU presented similar mechanical properties and water resistance with conventional WPU whose synthesis process involved organic solvents. In addition, the use of SDBS eliminated the employment of catalysts and reduced the reaction time and temperature of the chain extension step, resulting in the conservation of energy.