Synthesis and modification of spherical SiO₂ nanoparticles with different particle sizes and morphologies and their effects on the properties of thermoplastic polyurethane urea elastomers

Abstract A thermoplastic polyurethane urea (TPUU) elastomer with superior mechanical and thermal properties was recently reported from our group and synthesized by asymmetric aliphatic diisocyanate and diamine. In order to enhance its performance, this TPUU was further modified with spherical SiO₂ nanoparticles in this work, and the influence of the size and morphology of spherical SiO₂ nanoparticles on mechanical, thermal, and thermomechanical properties of TPUU was investigated. The results showed that spherical SiO₂ nanoparticles could significantly improve the mechanical, thermal, and thermomechanical properties of TPUU, which increased, with the decrease of the particle size of SiO₂ nanoparticles. Especially, compared with solid spherical SiO₂ nanoparticles, TPUU nanocomposites filled with hollow spherical SiO₂ (HSSiO₂) particles showed abnormal but unique stress–strain behavior, and their elongations at break increased with the decrease of particle size of HSSiO₂ nanoparticles.