## 2 Materials and Methods
### Chemicals and Characterization Methods  
Sulfur (colloidal powder, 99.5%, Carl Roth GmbH&Co. KG, Karlsruhe, Germany) and the vinyl monomers 1,3-disopropenyl benzene (97%, aber GmbH, Karlsruhe, Germany) and/or divinylbenzene (DVB, 80%, technical grade, Sigma-Aldrich Chemie GmbH, Taufkirchen, Germany) and styrene (freshly distilled, HRC chemicals, Purmerend, The Netherlands) were used as received without further purification.  
Gas Chromatography (GC) measurements were conducted by a Agilent 7820A gas chromatograph (Sim GmbH, Oberhausen, Germany) using tetrahydrofuran (HPLC grade) as a solvent and toluene as internal standard with the column CP7778 (50 m length, CP Wax 58 FFAP, Agilent, J&W GC Columns, Frankfurt, Germany) at a column pressure of 50 kPa with a flame ionization detector (FID). Hydrogen was used as mobile phase.  
Differential Scanning Calorimetry (DSC) was performed on a DSC 1 thermal analysis system (Mettler-Toledo GmbH, Giessen, Germany) at a heating and cooling rate of 10 \({}^{\circ}\)C\(\cdot\)min\({}^{-1}\) over the range of \(-\)50 to 150 \({}^{\circ}\)C under nitrogen atmosphere and the mid-points of the transitions were taken as \(T_{\mathrm{g}}\).  
Thermal Gravimetric Analysis (TGA) was carried out by a TGA 7 (PerkinElmer LAS GmbH, Rodgau, Germany) at a heating rate of 10 \({}^{\circ}\)C\(\cdot\)min\({}^{-1}\) under nitrogen atmosphere up to 800 \({}^{\circ}\)C.  
Elemental Analysis (Euro EA) was performed using an inductively coupled plasma optical emission spectrometry (ICP-OES) (HEKatech GmbH, Wegberg, Germany) with Carbon (C), Hydrogen (H), Nitrogen (N) and Sulfur (S), CHNS-Porapack PQS columns.  
PXRD measurements were obtained using an X'Pert Pro MPD model (PANalytical GmbH, Kassel, Germany) at room temperature with a Cu-K\({}_{\alpha}\) radiation source at 40 mA.  
Scanning electron microscopy (SEM) images were recorded on a Field Emission Scanning Electron Microscope (LEO 1525 FEG SEM, Carl Zeiss Microscopy GmbH, Jena, Germany) with an In-lens detector. An EHT of 5 kV and a WD of 5 mm was used. The samples for SEM were attached on a carbon surface with a carbon adhesive and vaporized with carbon.  
Tensile Experiments were performed on a materials testing machine from Zwick (Zwick GmbH&Co., Ulm, Germany) at a temperature of 25 \({}^{\circ}\)C. Samples were clamped tightly between the two jaws. A camera was fixed in front of the two jaws, to record the elongation process. The tensile test was carried out according to the international norm DIN EN ISO 527-2 with a multipurpose test specimen 5A.  
Dynamic Mechanical Analysis (DMA) was carried out on a HAAKE CTC from Thermo Fisher Scientific (Thermo Fisher Scientific GmbH, Karlsruhe, Germany). The storage moduli (\(E\)), loss moduli (\(E\)), and loss tangents (tan \(\delta\)) were obtained in the dual cantilever bending mode as a function of temperature over a range of \(-\)50-150 \({}^{\circ}\)C. The heating rate was 2 \({}^{\circ}\)C\(\cdot\)min\({}^{-1}\) and the frequencies were 0.3, 1, and 10 Hz. The test was performed according to DIN EN ISO 6721 with a multipurpose test specimen 5A without grip section.  
The specific contact resistance (\(\Omega\cdot\)cm) and the dielectric strength (kV\(\cdot\)mm\({}^{-1}\)) were measured by the company ELANTAS Europe GmbH (Hamburg, Germany). For the electrical measurements, blanks with a size of 10 \(\times\) 10 mm\({}^{2}\) are required for the first method and blanks with a size of 40 \(\times\) 40 mm\({}^{2}\) for the second method.