## 3 Results and Discussion
On the basis of the obtained FTIR results, the probable path of poly(GMA-co-TRIM)-SH copolymer degradation can be proposed (Figure 11). The presence of COS in the evolved gaseous mixture is the effect of the transesterification reaction between the thiol and carbonyl group followed by the rearrangement and finally the evolution of acrolein and carbon dioxide. \({}^{1}\)H NMR analysis confirmed the evolution of acrolein in the first stage of pyrolysis (Figure 12A,B). Upon analyzing the solid residues after heating the samples to 390 and 500 \({}^{\circ}\)C, distinct differences compared to the non-heated sample spectrum can be observed (Figure 10B). First of all, in the spectra of preheated samples, there is a lack of absorption bands derived from the SH group vibrations (2641, 2569 cm\({}^{-1}\)). This confirms the evolution of COS at the beginning of the copolymer thermal degradation [50; 51]. Additionally, in the spectrum region of the carbonyl stretching vibrations ( 390 \({}^{\circ}\)C), the new absorption band at 1803 cm\({}^{-1}\) is visible and moreover, the main band is broadened with the shoulder at about 1760 cm\({}^{-1}\). Furthermore, a significant new band at 1014 cm\({}^{-1}\) (C-O-C) appears. These changes are most probably connected with the creation of lactone groups in the copolymer structure during heating [49]. Figure 8: TG (**A**), DTG (**B**) and DSC (**C**) curves of poly(GMA-co-1,4 DMB)-SH and poly(GMA-co-TRIM)-SH copolymers obtained under non-oxidative conditions. Figure 10: FTIR spectra of (**A**) gases released from poly(GMA-_co_-TRIM)-SH at the maxima of emission; (**B**) preheated poly(GMA-_co_-TRIM)-SH. Figure 9: Three-dimensional FTIR diagrams of gaseous products of poly(GMA-_co_-TRIM)-SH (**A**) and poly(GMA-_co_-1,4 DMB)-SH (**B**) degradation. 2360-2326 cm\({}^{-1}\) (CO\({}_{2}\)), at 2173-2114 cm\({}^{-1}\) (CO) [39; 40; 46], at 2072-2047 cm\({}^{-1}\) (the C=O vibration in COS) [50; 51], at 1794-1700 cm\({}^{-1}\) (the C=O stretching vibrations) [40], at 1651 cm\({}^{-1}\) (the C=C stretching vibrations), at 1503 cm\({}^{-1}\) (the aromatic C=C stretching vibrations), at 1457 and 1376-1342 cm\({}^{-1}\) (the C-H deformation vibrations), at 986 and 943 cm\({}^{-1}\) (the =C-H out-of-plane deformation vibrations) and 896 cm\({}^{-1}\) (the out-of-plane C-H vibrations of 1,4 substitute aromatic ring) [41]. The maximum carbon dioxide emission is observed at 370 \({}^{\circ}\)C, whereas in the spectra collected at 383 \({}^{\circ}\)C and 483 \({}^{\circ}\)C, the intensity of absorption bands derived from organic groups is smaller than at 355 \({}^{\circ}\)C. However, it is possible to clearly distinguish in these spectra bands at 1180, 1125, 946, 910 and 816 cm\({}^{-1}\), which can be assigned to the presence of 1,4 DMB derivatives. The veracity of these assumptions was confirmed by analyzing the \({}^{1}\)H NMR spectrum of the compound's mixture obtained from TG analysis up to 390 \({}^{\circ}\)C. The spectral data revealed the presence of signals corresponding to acrolein, 1,4 DMB monomer, and a monomethacrylate derivative of hydroquinone, as depicted in Figure 12C. From the obtained spectral results, it can be assumed that the path of poly(GMA-_co_-1,4 DMB)-SH copolymer thermal degradation is similar to the poly(GMA-_co_-TRIM)-SH. Figure 14 presents the probable course of poly(GMA-_co_-1,4 DMB)-SH copolymer degradation. At the beginning, the transesterification of ester groups with -SH groups takes place, leading to the evolution of COS, acrolein and CO\({}_{2}\). The maximum COS emission is observed at 342 \({}^{\circ}\)C, while the organic products are emitted with the highest intensity at 355 \({}^{\circ}\)C. This observation indicates that copolymer decomposition begins with transesterification. This process results in the creation of lactone groups in the solid residue as shown by bands at 1802 and 1014 cm\({}^{-1}\) in the FTIR spectrum of the solid residue at 350 \({}^{\circ}\)C (Figure 13).