Synthesis and Characterization of Waterborne Poly(urethane-urea)s and Their Nanocomposites Containing Hydrophilic and Organophilic Clays

Novel combinations of water-dispersed poly(urethane-urea)s nanocomposites (NWPUU) were produced, in absence of organic solvent, comprising hydrophobic segments of poly hydroxyl-terminated polybutadiene (HTPB) and clays. Proper methods for the dispersion of montmorillonite (MMT): hydrophilic (clay Na+) or organophilic (clay 30B) in nanoscale are described, producing systems stable to sedimentation for, at least, six months. Besides HTPB, the monomers used in the synthesis were poly(propylene glycol) (PPG), dimethylolpropionic acid (DMPA), isophorone diisocyanate (IPDI) and the chain extenders: hydrazine (HYD) and ethylenediamine (EDA). Average particle size, by dynamic light scattering (DLS), and apparent viscosity were determined for the dispersions. The cast films were characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and water absorption and mechanical assays. The formation of exfoliated structures suggested the dispersion in nanoscale of both clays. The presence of the clays increased the mechanical resistance of the films analyzed. The results, in liquid and solid state, provided by the accessible characterization techniques suggested, complementarily, that there is greater miscibility between the rigid and flexible phases of the systems in which EDA was the chain extender. The eco-efficient aqueous poly(urethaneurea) s produced with low cost nanoloads can be a promise of high-performance materials for coatings and membranes.