NMR analysis of 1 indicated partial consumption of DCPD alkenes. Peaks at 3.5-4.0 ppm in the 1 H NMR spectra were consistent with signals from CHS groups (Fig. ). Signals between 60-75 ppm in the C NMR spectra were also consistent with the formation of C-S bonds (Fig. ). XRD analysis of 1 indicated that no crystalline sulfur was present (Fig. ), as did differential scanning calorimetry (DSC), which did not reveal the melting transition of sulfur. DSC was also used to measure a Tg = 3 °C (S16). Thermogravimetric analysis (TGA) indicated two mass losses, with the first onset at 160 °C and the second above 250 °C (Fig. ). Laser desorption mass spectrometry (LD-MS) revealed a mixture of species between m/z of 600 and 1000, each separated by 32 mass units, consistent with the proposed oligomeric polysulfide structure (Fig. ). Gel permeation chromatography (GPC) indicated a Mw of 1100 g mol -1 for 1 (based on comparison to polystyrene standards, S17). The polydispersity of Please do not adjust margins the product also increased over the reaction from Đ = 1.4 (60 minutes) to Đ = 1.9 (120 minutes) (S18). Finally, reduction of 1 with LiAlH4 provided the expected thiol products from reaction of sulfur with the strained norbornene alkenes of DCPD (Fig. ), as determined by GC-MS (S19-S25).