Photocatalytic and thermolytic Attenuation-Degradation mechanisms of perfluoroalkylsilane self assembled on TiO2 nanoparticles

In this work, we studied photocatalytic and thermolytic attenuation-degradation mechanisms of 1H, 1H, 2H, 2H - perfluorooctyltrichlorosilane (FOTS-SAM) coated titanium dioxide nanoparticles (TiO2-NPs). During thermolytic analysis, FOTS-SAM on TiO2-NPs was very stable up to 300 degrees C and further increase of temperature to 450 degrees C caused conformational disorders and the disorders increased up to 550 degrees C and complete degradation and desorption of FOTS-SAM from TiO2-NPs occurred above 550 degrees C. During photocatalytic analysis, FOTS-SAM on TiO2-NPs was stable up to 3 hrs and further UV exposure caused increase of conformational disorders up to 12 hrs and after 15 hrs complete degradation and desorption of FOTS-SAM from the TiO2-NPs. It is observed that FOTSSAM surface modification (i) passivates TiO2-NPs (ii) increases band gap from 3.2 eV to 5.7 eV and (iii) attenuates UV induced electron-hole pair (e(-), h(+)) generation. Further observed that the FOTS-SAM-TiO2-NPs were superhydrophobic but under long UV exposure and high temperature they became hydrophilic. PLLAnanocomposites filled with FOTS-SAM-TiO2-NPs show excellent mechanical properties and stability compared to PLLA-nanocomposites filled with uncoated TiO2-NPs. Experimental investigations confirm that FOTS-SAM on TiO2-NPs acts as photocatalytic and thermolytic attenuation layer, super hydrophobic layer and enhances stability and mechanical properties of nanocomposites.

Automated summary

In this study, it was found that surface modification of TiO2-NPs with FOTS-SAM enhances stability and mechanical properties of nanocomposites, reduces UV-induced electron-hole pair generation, and results in superhydrophobic behavior. The FOTS-SAM coating undergoes degradation and desorption under high temperatures, demonstrating its dual role as a photocatalytic and thermolytic attenuation layer.