## 3 Results and Discussion
Figure 4: FTIR spectra of (**A**) gases released from poly(GMA-co-1,4 DMB) at the maxima of emission; (**B**) preheated poly(GMA-co-1,4 DMB). Figure 5: FTIR spectra of gaseous decomposition products of poly(GMA-co-1,4 DMB) at 269 \({}^{\circ}\)C and the reference spectra of GMA monomers and acrolein. Figure 6: The possible decomposition path of the 1,4 DMB crosslinked copolymer (**A**) and TRIM crosslinked copolymer (**B**). TG, DTG and DSC curves for the studied microspheres after functionalization are presented in Figure 8, whereas the T5\({}_{\rm{50\%}}\), T50\({}_{\rm{50\%}}\) and T\({}_{\rm{max}}\) temperatures and the corresponding mass losses (\(\Delta\)m) are given in Table 1. From the DTG curves, it can be seen that both copolymers undergo a two-stage degradation process after functionalization. Each degradation stage is endothermic, which is confirmed by the DSC curves. The thermal resistance of the thioglycyclic acid functionalized copolymers, inferred from T5\({}_{\rm{50\%}}\) values, increased compared to the initial copolymers by 54 \({}^{\circ}\)C for poly(GMA-_co_-TRIM)-SH and by 22 \({}^{\circ}\)C for poly(GMA-_co_-1,4 DMB)-SH. The functionalized copolymers, compared to the initial ones, show no mass loss at around 250 \({}^{\circ}\)C (T\({}_{\rm{max1}}\)), which is associated with the degradation of the structure fragments containing oxirane groups. Poly(GMA-_co_-TRIM)-SH reveals the first maximum value of degradation (T\({}_{\rm{max2}}\)) at 344 \({}^{\circ}\)C and loses 89.2% of its mass at this stage (\(\Delta\)m\({}_{2}\)). The second maximum value (T\({}_{\rm{max3}}\)) is observed at 531 \({}^{\circ}\)C with a mass loss of 9.5% (\(\Delta\)m\({}_{3}\)). Poly(GMA-_co_-TRIM)-SH has a higher thermal resistance by 16 \({}^{\circ}\)C in comparison with poly(GMA-_co_-1,4 DMB)-SH. Regarding poly(GMA-_co_-1,4 DMB)-SH, the first degradation maximum (T\({}_{\rm{max2}}\)) occurs at 355 \({}^{\circ}\)C and is related to a mass loss of 83.9%. In contrast, the second maximum value (T\({}_{\rm{max3}}\)) is observed at 479 \({}^{\circ}\)C with a mass loss of 10.5%. The second maximum value (T\({}_{\  
16.6% (\(\Delta\)m\({}_{3}\)). In the case of functionalized copolymers, contrary to the initial copolymers, the TRIM-crosslinked copolymer has a higher thermal resistance. This may be due to the fact that this copolymer contained more oxirane groups in its structure before functionalization than the copolymer crosslinked with 1,4 DMB, as evidenced by the higher value of the epoxide number. From the 3D-FTIR diagram of the gaseous pyrolysis products of poly(GMA-co-TRIM)-SH (Figure 9), the volatile spectra that evolved at the emission maxima were extracted. The spectrum collected at 353 \({}^{\circ}\)C (Figure 10A) shows absorption bands above 3500 cm\({}^{-1}\) (the -OH stretching vibrations), at 3100 cm\({}^{-1}\) (from the stretching vibrations of the =C-H) [39], in the range of 2970-2866 cm\({}^{-1}\) (the C-H stretching vibrations), at 2806-2774 cm\({}^{-1}\) (the aldehyde C-H stretching vibrations) [49], at 2360-2326 cm\({}^{-1}\) (indicating CO\({}_{2}\) presence), at 2173-2114 cm\({}^{-1}\) (for CO) [39; 40; 46], at 2072-2047 cm\({}^{-1}\) (representing the C=0 vibration in carbonyl sulfide (COS) [50; 51]), at 1790-1713 cm\({}^{-1}\) (for the C=0 stretching vibrations) [40], at 1651 cm\({}^{-1}\) (for the C=C stretching vibrations), at 1457 and 1376-1342 cm\({}^{-1}\) (for the C-H deformation vibrations), at 1131 cm\({}^{-1}\) (for the C-O deformation vibrations) and at 943 cm\({}^{-1}\) (for the =C-H out-of-plane deformation vibrations) [41]. Considering the 3D FTIR spectrum, it is evident that the maximum CO\({}_{2}\) emission occurs between the first and second steps of copolymer degradation around 403 \({}^{\circ}\)C. In the spectrum from T\({}_{\rm max3}\), only the absorption bands derived from water (3600-3500 and 1500-1600 cm\({}^{-1}\)) and CO\({}_{2}\) (2360-2326 and 671 cm\({}^{-1}\)) can be observed [49].