High solid and high stability waterborne polyurethanes via ionic groups in soft segments and chain termini

• Published in: Journal of colloid and interface science 2009-08, Vol.336 (1), p.208-214
• Main Authors: Lee, S.K., Kim, B.K.
• Format: Article
• Language: English
• Subjects: Chains; Chemistry; Colloidal state and disperse state; Dispersions; Exact sciences and technology; General and physical chemistry; Ionic content; Polyols; Polyurethane resins; Segments; Solid content; Stability; Surface physical chemistry; Swelling; Terminal ion; Terminals; Waterborne polyurethane
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2009.03.028

By placing ionic groups at chain termini of polyurethane stable dispersions of high solid content (45%) have been made with high swelling resistance at low ionic content (2%) (T2-650-45). High solid and high stability waterborne polyurethanes were molecularly designed and synthesized. The positions and concentrations of the anionic groups were varied, along with the molecular weights of the polyol. It was found that the dispersions containing ionic groups at the chain termini (called terminal ions) gave the smallest dispersion size, and the highest dispersion stability and viscosity, whereas the hard ions, containing ionic groups in the hard segments, resulted in the greatest swelling in water. However, the mechanical and dynamic mechanical properties of the dispersion cast films were similar. It was demonstrated that highly stable dispersions with a high solid content (45%) can be obtained at a low ionic content (2%) by simply incorporating the ionic groups at the flexible chain ends. The results were interpreted in terms of the high mobility and low free energy of the chain ends.