## 3 Results and Discussion  
The subject of the current study is the characterization of the thermal behavior under pyrolysis conditions of polymer microspheres containing oxirane rings or thiol groups in their structure. Poly(GMA-_co_-TRIM) and poly(GMA-_co_-1,4 DMB) microspheres were synthesized using seed swelling polymerization with GMA functional monomer and the following crosslinking agents: TRIM and 1,4 DMB. The synthesized microspheres were subsequently modified with thioglycolic acid to introduce thiol groups on their surface. The epoxide number of starting copolymers was determined using HCl/dioxane reverse titration. The value obtained was 1.23 mmol/g for poly(GMA-_co_-TRIM) and 1.12 mmol/g for poly(GMA-_co_-1,4 DMB). The sulfur content of the copolymers after functionalization, determined through elemental analysis, was 3.12% and 4.51% for poly(GMA-_co_-TRIM)-SH and poly(GMA-_co_-1,4 DMB)-SH, respectively. The thermal properties of the studied copolymers were characterized based on the results obtained from thermogravimetric analysis and differential scanning calorimetry. In Figure 2, TG, DTG and DSC curves for poly(GMA-_co_-1,4 DMB) and poly(GMA-_co_-TRIM) are shown. Table 1 presents the temperatures of 5% and 50% mass loss (T\({}_{5\%}\), T\({}_{50\%}\)), the temperatures of maximum mass loss (T\({}_{\rm max}\)) and the corresponding mass loss (\(\Delta\)m). The DTG curves indicate that the starting copolymers undergo a three-step degradation process in an inert atmosphere, regardless of the crosslinking agent used. Poly(GMA-_co_-TRIM) shows the first maximum value of degradation at 251 \({}^{\circ}\)C and is accompanied by a mass loss of 39.4% (\(\Delta\)m\({}_{1}\)). The second maximum value occurs at 375 \({}^{\circ}\)C with a mass loss of 49.3% (\(\Delta\)m\({}_{2}\)). The third maximum value is observed at 519 \({}^{\circ}\)C, with a mass loss of 9.6% (\(\Delta\)m\({}_{3}\)). The DSC curve reveals three distinct maxima that correspond to the maxima on the DTG curve, indicating that the various stages of copolymer degradation are overall endothermic processes. Based on the T\({}_{5\%}\) value, it can be concluded that poly(GMA-_co_-TRIM) is stable up to 238 \({}^{\circ}\)C under non-oxidative conditions. In contrast, the thermal stability of poly(GMA-_co_-1,4 DMB) copolymers is higher by about 15 \({}^{\circ}\)C in comparison with the TRIM-crosslinked material. The first stage of poly(GMA-_co_-1,4 DMB) decomposition occurs at 269 \({}^{\circ}\)C and is connected with a mass loss of 33.8% (\(\Delta\)m\({}_{1}\)). The second stage occurs at 388 \({}^{\circ}\)C with a mass loss of 49.9% (\(\Delta\)m\({}_{2}\)), and the third at 556 \({}^{\circ}\)C with a mass loss of 11.2% (\(\Delta\)m\({}_{3}\)). The course of TG curves for both copolymers is similar to the previously reported porous microspheres crosslinked with 1,4 DMB or TRIM analyzed in a non-oxidative atmosphere [13; 35]. The course of the DSC curve of poly(GMA-_co_-1,4 DMB) differs in comparison with the TRIM-crosslinked copolymer. In the temperature region between 100 and 250 \({}^{\circ}\)C, the exothermic peak evolving into an endothermic peak is observed for this copolymer, while the next peak is endothermic. The explanation for this overall exothermic peak should be found in the mechanism of the degradation of the copolymer in a non-oxidizing atmosphere. According to literature sources, the thermal degradation of the polyGMA homopolymer starts with endothermic depolymerization [36] followed by exothermic isomerization of the oxirane ring to the carbonyl group [16; 37]. In the case of poly(GMA-_co_-1,4 DMB), decomposition is also triggered by endothermic depolymerization but it is a complex process with overlapping reactions, including the exothermic isomerization of oxirane. Additionally, the mass loss at the first degradation step is significant and shifts the DSC signal in the exothermic direction.