## 3 Results and Discussion
### Thermal Properties
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Monomer (wt \%)**} & \multirow{2}{*}{**pS-DVB (\({}^{\circ}\)C)**} & \multirow{2}{*}{**pS-DIB (\({}^{\circ}\)C)**} & \multicolumn{3}{c}{**Terpolymer (monomer content: 20 wt \%)**} \\ \cline{4-6}  & & & **Material** & \(T_{\rm g}\) (\({}^{\circ}\)C) & **Cross-linker ratio** \\ \hline
10 & 212 & - & S\({}_{\rm 8}\) & 216 \(\pm\) 4 & - \\
15 & 231 \(\pm\) 21 & 226 \(\pm\) 11 & - & 216 & DVB/DIB 5:15 \\
20 & 226 \(\pm\) 8 & 215 \(\pm\) 7 & pS-DVB-DIB & 224 & DVB/DIB 10:10 \\
25 & 227 \(\pm\) 8 & 224 \(\pm\) 14 & - & 234 & DVB/DIB 15:5 \\
30 & 241 \(\pm\) 4 & 221 \(\pm\) 7 & 216 & DVB/STY 10:10 \\
35 & 231 \(\pm\) 3 & 212 & pS-DVB-STY & 213 \(\pm\) 4 & DVB/STY 15:5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Decomposition temperature at 5% weight loss (TGA). Figure 5: TGA-thermograms with varying incorporated monomer content: (**a**) pS-DVB; (**b**) pS-DIB. elemental sulfur. This residue does not crystallize in the cooling step, so neither \(T_{\rm c}\) nor \(T_{\rm m}\) appear afterwards, which shows that a complete S\({}_{8}\)-conversion has taken place after the thermal treatment. \(T_{\rm g}\) and other transitions are determined for all sulfur copolymers in the second heating step (Figure 6). The more pronounced first step, the \(T_{\rm g}\), shows the transition from glass to plastic in the pS-DVB and from brittle to thermoplastic in the pS-DIB. The \(T_{\rm g}\) increases by higher cross-linking density or molecular weight as shown in pS-DIB (Figure 7b). pS-DVB (Figure 7a) does not behave accordingly. From an amount of 17.5 wt % DVB, the \(T_{\rm g}\) tends to decrease with an increase of added DVB content. At a lower scale, an increase in \(T_{\rm g}\) with increasing monomer content [11] can be observed in the pS-DVB. This divergence, which occurs in comparison to a 200 g scale, can be explained by the chain reduction of pS-DVB (\(\geq\)30 wt % DVB) caused by exceeding a temperature of 200 \({}^{\circ}\)C (gel effect) [3]. Likewise, in the case of a higher DIB content, the \(T_{\rm g}\) is higher at a lower scale [8; 10]. The \(T_{\rm g}\) of the terpolymer tends to increase when the added styrene content is decreased. The decrease of the DIB content in the DVB-based terpolymers leads to an increase of \(T_{\rm g}\) due to higher cross-linking abilities of DVB in comparison with DIB monomers (Figure 8). Consequently, a higher cross-linking density leads to a higher \(T_{\rm g}\)[29]. The work of [PERSON] confirmed that styrene reduces the \(T_{\rm g}\) (similar to DIB) due to its relatively low \(T_{\rm g}\) and viscous, flexible ductility. Consequently, it shows properties of a plasticizer [13]. Figure 6: DSC-thermogram: (**a**) pS-DVB\({}_{10-35}\); (**b**) pS-DIB\({}_{15-35}\). Representation of both heating steps and of the cooling step. Heating and cooling rate: 10 \({}^{\circ}\)C-min\({}^{-1}\). Figure 7: Glass transition \(T_{\rm g}\) of the sulfur copolymers. (**a**) pS-DVB; (**b**) pS-DIB. The second lower transition could not be assigned, but its presence can be confirmed by the thermogram in the Dynamic Mechanical Analysis (DMA). This deformation transition occurs in pS-DVB as a softening point and in pS-DIB as a transition to a viscous melt. This occurs for all polymers at a temperature of approx. 131.5 \(\pm\) 1 \({}^{\circ}\)C.  
To become a viscous melt, despite the cross-linked structure, allows pS-DIB to act as a self-healing material. This behavior occurs due to the lower dissociation energy of S-S bonds (dynamic covalent bonds) in longer S-S chains (33 kcal\(\cdot\)mol\({}^{-1}\)) [30]. Upon thermal activation, the microstructure of the sulfur copolymer backbone cleaves and reorganizes itself into a different macromolecular framework. pS-DVBs exhibit only a slight softening point at high temperatures (>130 \({}^{\circ}\)C) without a molten state. Thus, pS-DVBs provide excellent properties in terms of temperature resistance and shape retention.