## 3 Results and Discussion  
### Confirmation of Silica Silization Reaction  
FTIR spectra recorded for the hydrophilic nanosilica, as well as for the different silanized types of nanoparticles, are depicted in Figure 1. The measurements were taken in the narrow range of 3200-1350 cm\({}^{-1}\) in order to avoid any possible attenuation of the interesting peaks induced by the much stronger intensities at 1100 and 810 cm\({}^{-1}\), usually attributed to Si-O-Si and Si-OH vibrations of the neat nanoparticles [49]. Unlike the non treated silica, the absorbance peaks from 2965 to 2844 cm\({}^{-1}\) due to C-H stretching were detected for the total of the organomodified silica nanoparticles. Fillers modified with MPS, ACPS, and the blends of MPS-OTMS, ACPS-OTMS, and MPS-ACPS presented a peak at 1730 cm\({}^{-1}\) assigned to C=O bonds of the methacylated groups. The characteristic peak at 1640 cm\({}^{-1}\) for the aforementioned silanes and at 1465 cm\({}^{-1}\) revealed C=C stretching of vinyl groups and C-H bending vibrations correspondingly. These FTIR findings rather denote the successful siliarization of silica nanoparticles with each tested organosilane system. The thermal stability results associated with the pure silica and nanofillers modified with different silanes and their corresponding blends are illustrated in Figure 2. The TG plots of residual mass (%) versus temperature (Figure 2a) reflect the different degradation tendencies due to the presence and the variety of the siliacs' organic content. It can be seen that the overall mass loss for all tested nanoparticles varied from 3% to 6%. The samples of silanized silica exhibited mainly a two-step mass loss as the temperature raised with constant rate. In particular, the first step was accomplished at 300 \({}^{\circ}\)C with maximum degradation rates at 235 \({}^{\circ}\)C, 150 \({}^{\circ}\)C, 242 \({}^{\circ}\)C, 240 \({}^{\circ}\)C, 230 \({}^{\circ}\)C, and 227 \({}^{\circ}\)C for MPS, OTMS, MPS-OTMS, ACPS, ACPS-OTMS, and MPS-ACPS respectively, as was indicated by the differential thermogravimetric analysis curves, DTG (Figure 2b). This specific step could be ascribed to the removal of the absorbed moisture in the surface of silica and/or the removal of physically absorbed organosilanes [23,41]. The second step seemed to take place over 300 \({}^{\circ}\)C, that is, between 356-542 \({}^{\circ}\)C for MPS, 453-586 \({}^{\circ}\)C for OTMS, 405-567 \({}^{\circ}\)C for MPS-OTMS, 355-554 \({}^{\circ}\)C for ACPS, 387-571 \({}^{\circ}\)C for ACPS-OTMS, and 322-523 \({}^{\circ}\)C for MPS-ACPS (Figure 2a) accompanied with maximum degradation rates at 442 \({}^{\circ}\)C, 534 \({}^{\circ}\)C, 518 \({}^{\circ}\)C, 447 \({}^{\circ}\)C, 508 \({}^{\circ}\)C, and 446 \({}^{\circ}\)C (Figure 2b) correspondingly. The latter step is attributed to the removal of the silane molecules chemically bonded to the surface of silica and to the condensation of the surface silanol groups [41]. The non-treated silica showed a main degradation step relative to the loss of absorbed water molecules, while silane molecules were absent. Moreover, the silane blends exhibited inflection points within the temperatures of those of their initial silanes. Regarding the maximum degradation rates, the tested samples followed the sequence: OTMS > MPS-OTMS > ACPS-OTMS > ACPS > MPS-ACPS > MPS > Neat silica (Figure 2b). Taking into account the duration of thermal decomposition, the following decreasing order was observed: ACPS > MPS-ACPS > MPS > ACPS-OTMS > MPS-OTMS > OTMS > Neat silica, whereas the thermal stability  
Figure 1: Comparative FTIR spectra between untreated and diverse organomodified silica nanoparticles. of the studied nanoparticles was: Neat silica > MPS > OTMS > ACPS > ACPS-OTMS > MPS-OTMS > MPS-ACPS (Figure 2a). A combining mass loss in relatively labile silane blends involving the thermal behavior effect of the starting silanes accounts for their lower stability in comparison with the individual organosilanes.