Protean morphology of waterborne polyurethane dispersion: An overview of nanoparticles from sphere to irregular elongated shape

Polyurethane has been significantly developed for decades due to the valuable thermoplastic, elastomeric and thermoset behavior on the basis of the block chains consisting of hard and soft segments. With the advances of green chemistry and nanoscience, the synthesis of green, homogenous novel polyurethane products with high performance have gained great attention. In this review, we firstly introduced recent synthesis processes of waterborne polyurethane particles with various shape and size. Then, the impact factors on the morphology of polyurethane particles were discussed and analyzed. Thirdly, the nanoparticles formation and aggregation processes were simulated to illustrate the diverse polyurethane nanoparticles bulk structures. Finally, the robustness and free-standing properties of nanoparticles were presented significantly to broaden applications of polyurethane in carriers of drug, binder, coatings, adhesives, stabilizer and surfactant areas, etc. In a word, the preparation of polyurethane particles in aqueous is necessary and urgent, as well as the mechanism.