## 3 Results
### Thermal Properties of PS/OMt Nanocomposites  
The differences in the TGA-DTG curves of the PS and PS/OMt are shown Figure 7. The samples that were prepared with Si-P-Mt, P-Si-Mt, H-Si-P-Mt, and H-P-Si-Mt were labeled as PS/Si-P-Mt, PS/P-Si-Mt, PS/H-Si-P-Mt, and PS/H-P-Si-Mt, respectively. The degradation temperatures (\(T_{\text{-50\%}}\), 5% mass loss temperature; \(T_{\text{-50\%}}\), 50% mass loss temperature; \(T_{\text{max}}\), obtained from DTG) are listed in Table 4. \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Sample** & \(\mathbf{T_{\text{-50\%}}\) (\({}^{\circ}\)**C**)} & \(\mathbf{T_{\text{-50\%}}\) (\({}^{\circ}\)**C**)} & \(\mathbf{T_{\text{max}}\) (\({}^{\circ}\)**C**)} \\ \hline PS & 359 & 401 & 403 \\ PS/Si-P-Mt & 374 & 416 & 419 \\ PS/P-Si-Mt & 379 & 420 & 422 \\ PS/H-Si-P-Mt & 382 & 427 & 430 \\ PS/H-P-Si-Mt & 386 & 432 & 435 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: TGA and DTG data of pure PS and PS/OMt nanocomposites. It is worth mentioning that the thermal stability of the PS/OMt nanocomposites was considerably enhanced compared with pure PS, which could be associated to the nanoscale OMt layers, with a large surface preventing the out-diffusion of the volatile decomposition products. At 5% mass loss, the \(T_{-5\%}\) of PS/Si-P-Mt, PS/P-Si-Mt, PS/H-Si-P-Mt, and PS/H-P-Si-Mt were about 374 \({}^{\circ}\)C, 379 \({}^{\circ}\)C, 382 \({}^{\circ}\)C, and 386 \({}^{\circ}\)C, respectively, which was 15 \({}^{\circ}\)C, 20 \({}^{\circ}\)C, 23 \({}^{\circ}\)C, and 27 \({}^{\circ}\)C higher than that of PS. Also, the \(T_{\max}\) was improved from 403 \({}^{\circ}\)C for the PS, to 419 \({}^{\circ}\)C, 422 \({}^{\circ}\)C, 430 \({}^{\circ}\)C, and 435 \({}^{\circ}\)C for PS/Si-P-Mt, PS/P-Si-Mt, PS/H-Si-P-Mt, and PS/H-P-Si-Mt, respectively. These indicated that the P-Si-Mt exhibited a better effect on the thermal stability improvement of PS than the Si-P-Mt. Additionally, the PS/H-Si-P-Mt and PS/H-P-Si-Mt had relatively higher decomposition temperatures as compared with those of the PS/Si-P-Mt and PS/P-Si-Mt. This could be attributed to a better interfacial interaction and dispersion that was formed in the polymer matrix for the triple-modified nanofillers. In contrast to the double-functionalized nanofillers, the triple-modified clays tend to create a better labyrinth pathway, to slow down the diffusion of volatile gas in the polymer matrix, as illustrated in Figure 8. According to previous studies [47; 48], a better improvement in thermal stability for the nanocomposites with different fillers was observed in air or oxygen, compared to a nitrogen atmosphere. Under an oxidizing atmosphere, the differences in thermal stability between PS and PS/OMt will be, very likely, much higher, due to the shielding effect of OMt on the diffusion of gases in the polymer. As denoted by the red circles, the tightly stacked silicate region in the TEM images of Figure 8A,B clearly showed a typical intercalated structure, with narrow interlayer spacing. However, in the case of the H-Si-P-Mt sample, the nanocomposites showed a mixture of both intercalated and exfoliated structures, revealing an intermediate state from intercalation to exfoliation. The exfoliated structures, which indicated that the individual silicate layers were kept free from the adjacent clay layers in the polymer matrix, were observed in the Figure 8D, as denoted by the yellow arrows. These proved that the triple-functionalized samples possessed greater affinity and better interaction towards the PS matrices, due to the larger interlayer spacing, relative to the dual-functionalized samples. Our group has previously shown that the polystyrene chains can enter into the OMt to increase the interlayer spacing of OMt, leading to intercalated and/or exfoliated structures in the resulting nanocomposites, during the soap-free emulsion polymerization [25]. The complete exfoliation of the H-P-Si-Mt nanofiller in the PS matrix was also due to a larger space for the ease of the PS chains penetration.