Figure 3.
Thermogravimetric behavior and surface functionalization regimes. (a) Increasing magnitude of 720–725 cm–1 and 1147, 1248, and 1350 cm–1 peaks are indicative of increasing C–H265 and C–F266 groups, respectively. This is interpreted as an enhanced surface density of fluoro-based moieties on nanoparticles. (b) Relative peak intensity (normalized) at 655 and 704 cm–1 with respect to a control sample. (c) The T–50 (midpoint of degradation) revealed a gradual drop (ΔT ≈ 74 °C), contrasting Td-onset (onset of decomposition). This decreased from a reaction grafting ratio of 1:1 with 448 °C down to 374 °C at reaction grafting ratios of 6:1 onward to 20:1 with a range of ca. ± 15 °C in variations. (d) Thermogravimetric analysis of Td-onset revealed consistent drops from ca. 430 °C across reaction graft ratios of 1:1 to 4:1. A sharp shift to 370 °C (ΔT ≈ 60 °C) was observed when increasing the reaction graft ratio beyond 6:1 and was tested up to 12:1 with highly consistent behaviors. Weight percentage losses at maximum thermal decomposition are ca. 20%, 31%, 44%, and, finally, 54% w/w at 1:1, 2:1, 4:1, and 6:1 (and beyond), respectively.