Water-Dispersible Polyurethanes Obtained by the Controlled Alternation of the Segments of Poly(propylene glycol), Poly(ethylene glycol) and Urethane

Novel polyurethanes with exactly controlled structures, that is, alternating block polyurethanes based on poly(propylene glycol) and poly(ethylene glycol) that are linked through urethane segments, were synthesized by polyaddition polymerization. A reaction between isocyanate groups from the poly(propylene glycol) tolylene 2,4-diisocyanate terminated component and the hydroxyl groups of the poly(ethylene glycol) component as a chain extender produced the controlled structure. The chemical structure was characterized by nuclear magnetic resonance spectra, Fourier transform infrared spectroscopy, and varying poly(ethylene glycol) molecular weights. The thermal property was investigated by differential scanning calorimetry and thermogravimetric analysis. The wettability was studied using the static contact angle of water. These polymers exhibit remarkable crystallization features and very good dispersion in water. The presence of urethane segments on the molecular chains provides good stability for the dispersion in water. The obtained polymers possess good thermal properties. Differential scanning calorimetry and polarized optical microscopy revealed improved dispersion in water and increased crystallization capability in correlation with the increase of the PEG molecular weight. These polyurethanes would be promising candidates for friendly environmental polymer materials. Graphical Abstract