Polyurethane-imide-polyhedral oligomeric silsesquioxane hybrid nano-composites: Synthesis, structure and thermal mechanical stability

In order to improve thermo-stability of polyurethane (PU), both imide group and polyhedral oligomeric silsesquioxane (POSS) were introduced into PU backbones, and PU-imide-POSS hybrid nano-composites (PUI-POSS) were synthesized with high reaction efficiency. The spherical domain formed through strong aggregation effect of POSS units, and the trend of micro-phase separation of PU was strengthened. The TDI-POSS aggregates with urethane linkage dispersed uniformly in PU matrix and maintained self-assembling ability by the formation of crystal phases with tight crystalline lamella. With increasing POSS content, the thermal degradation temperature and char yield increased, and degradation rate decreased remarkably. Moreover, the difference of degradation temperature significantly increased with degradation progressing, indicating more pronouncing thermo-stabilizing effect of POSS units at high temperature. Compared with PUI, T-60% of PUI-POSS with 14.96mass POSS increased by 270 degrees C. The degradation activation energy showed a large improvement, and high storage modulus can be kept with increasing temperature by introducing POSS units.