Influence of TiO2@SiO2 hybrid nanoparticles on characteristics, fluidization behavior and coating performance of PA12/PPO blend.

In this study, TiO2@SiO2 (TS) hybrid nanoparticles were synthesized via the Stöber sol-gel method and incorporated into a PA12/PPO (90/10 wt%) blend at loadings of 1, 3, and 5 wt% by melt compounding, for application as a fluidized bed coating (FBC) material. The core-shell architecture of the TS nanoparticles was confirmed by field-emission scanning electron microscopy (FE-SEM), Fourier-transform infrared spectroscopy (FT-IR), and energy-dispersive X-ray (EDX) analysis. Among all formulations tested, the 3 wt% TS nanocomposite (TS-3) exhibited the most favorable balance of coating properties, surpassing the neat PA12/PPO blend and the equivalent TiO2 nanocomposite (T-3) in tensile strength, abrasion resistance, and coating flexibility. FE-SEM revealed a fibrous fracture texture in TS-3, compared with interfacial voids around neat TiO2 particles, suggesting differences in polymer-filler adhesion. Hydrogen bonding between silanol groups of the SiO2 shell and amide groups of PA12 is proposed as a possible contribution to these interfacial interactions. A notable finding of this study is that neat TiO2 lowered the peak decomposition temperature relative to the unfilled blend, possibly through surface-mediated promotion of thermal chain scission involving Lewis-acidic sites; the SiO2 shell may limit such interactions, while the TS-3 nanocomposite exhibited a temperature at 10% mass loss 25.7 °C higher than that of the neat blend. Dynamic mechanical analysis confirmed substantial positive shifts in the glass transition temperatures of both the PA12 and PPO phases for the TS-3 nanocomposite, reflecting strong polymer-filler interfacial interactions. The TS-3 FBC also exhibited lower thickness variability and higher surface gloss than the unfilled blend and its TiO2-filled counterpart. These results establish the PA12/PPO/TS nanocomposite system as a multifunctional FBC coating material with simultaneously enhanced mechanical, thermal, UV-barrier, and surface appearance performance.