Surface modification of TiO2 particles with 12-hydroxy stearic acid and the effect of particle size on the mechanical and thermal properties of thermoplastic polyurethane urea elastomers

The efficient surface modification of titanium dioxide (TiO₂) particles with different sizes was first carried out with “water only method” (Appl. Surf. Sci. 2018, 447, 664–672) developed in our group using 12-hydroxy stearic acid (12-HSA) as the modifier. The 12-HSA-modified TiO₂ particles with different sizes were then used to explore their effect on the mechanical and thermal properties of a thermoplastic polyurethane urea (TPUU) elastomer with superior mechanical and thermal properties produced newly in our lab using nonsymmetric alicyclic diisocyanate and diamine. Orthogonal experimental results showed that the order of impact of each factor on the modification efficiency of TiO₂ particles was: Temperature > time > modifier content. It was found that, in the nanometer (≤100 nm) range, smaller particles were more helpful to enhance the tensile strength of the TPUU elastomer, while larger ones to increase more significantly the elongation at break. Besides, the TiO₂/polyurethane urea nanocomposites exhibited much better thermomechanical performance than the pristine TPUU elastomer, and the thermomechanical performance of the nanocomposites increased with decreasing particle size.