“…The peaks at 1514, 1346, 1105, and 721 cm − 1 in the monomer spectrum are ascribed to the stretching vibrations of non-aromatic heterocycle thione (tautomeric structure II in Figure 1 c). Specifically, the bands at 1514 and 1346 cm − 1 may be ascribed to C=N and C-N stretching vibrations [ 12 ] in the triazine ring, while that at 1105 cm − 1 is assigned to C=S stretching vibrations [ 13 ]. In the polymer, the peaks at 1514, 1346, and 720 cm − 1 are shifted to 1460, 1220, and 821 cm − 1 , respectively, while the trace of the C=S peak is observed in the band shoulder at about 1140 cm − 1 .…”