Synthesis and Properties of Waterborne Poly(urethane urea)s Containing Polydimethylsiloxane

To obtain flexible waterborne poly(urethane urea) (WBPU) coatings with functionalities such as shape recovery and water resistance, we synthesized a series of WBPUs by a prepolymer mixing process from hexamethylene diisocyanate, polyol, 2,2-bis(hydroxymethyl) propionic acid, ethylenediamine, and triethylamine with polyol blends [hydroxyl-terminated polydimethylsiloxane (PDMS) with a number-average molecular weight of approximate to 550 and poly (tetramethylene oxide) glycol (PTMG) with a number-average molecular weight of 650] of different molar ratios. The effects of the PDMS content in PDMS/PTMG on the dynamic thermal and mechanical properties, hardness, tensile properties, water resistance (water absorption, contact angle, and surface energy), and shape-memory properties of WBPU films were investigated. As the molar percentage of PDMS in WBPUs increased, the storage modulus, tensile strength and modulus, elongation at break, hardness, and shape-retention rate (30-15%) decreased; however, the water resistance and shape-recovery rate (80-90%) increased. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 120: 212-219, 2011