# Doped Epoxy Resins as an Alternative to Luminescent Optical Sensors
## 3 Results and Discussion
### Thermal and Spectroscopic Analysis
As the temperature increases, the released elements are the first to be registered by the mass analyzer. Ion analysis at the second DTG maximum confirms this statement, where all ions typically present in the decomposition range are observed. The low conversion for these substances (Table 3) also confirms the assumption. DSC curves confirm the occurrence of endothermic processes, and their maximums fall approximately around the registration of 1 wt.% mass loss and the second maximum on the DTG curve. There are also maxima in the range of 300-380 \({}^{\circ}\)C, unrelated to the maximum on the DTGcurve. But looking at Figure S1J-L, you can see that they are within the range of the sample decomposition. The multitude of these maxima indicates the complexity of the decomposition process related to the diversity of the obtained polymer structures. The situation is completely different in the case of compositions containing 33 wt.% of NVP (sample series No.13-15). For the No.13 and No.15 sample series, only around the second DTG maximum (around 230-240 \({}^{\circ}\)C), few ions indicating the presence of a vinyl group (\(m/z=27\)) or an active solvent fragment (\(m/z=56\)) are detected. In the case of series No.14, the first maximums recorded on the DTG curve are slightly above 200 \({}^{\circ}\)C, which proves that the addition of 2.7-NAF.EP does not negatively affect the thermal properties of the matrix. Also, in this case, few ions were recorded in the mass spectra (\(m/z=14\), 15, 27, 40, 41, 56). The second DTG maximum recorded for samples No.14-15 is located at a temperature of 260.6 \({}^{\circ}\)C (Table 4), and additional ions \(m/z=28\)-31.43 appear in this region. For samples No.14-30, this maximum was determined at a temperature of 238.3 \({}^{\circ}\)C, and the mass spectra indicate the presence of ions \(m/z=44\), 54, and 55 (apart from those already mentioned). The second DTG maximum for samples No.14-60 was registered at 421.1 \({}^{\circ}\)C. This means that ions for which mass is related to the fragments of the EB600 appear only in the temperature range of the proper sample decomposition. This, in turn, allows us to assume that the discussed samples show the best thermal properties of those presented so far (the conversion of double bonds above 90%, Table 3). The profile of endothermic transformations is similar to analogous samples with 25 wt.% NVP content, except for those around the second DTG maximum, where two DSC maximums are observed. For the last series of samples (No.16-18), 1 wt.% mass loss was recorded in the range of 90-115 \({}^{\circ}\)C and it cannot be stated that exposure time or the started composition influenced this value. The first maximum on the DTG curve for samples No.16-15 and the first and second maximum for samples No.16-30 are associated with the presence of ions \(m/z=17\), 18, 27, 28, 29, 40-44, 54-56, 68, and 82, which indicates the relatively early appearance of active solvent fragments. For samples No.17-30, No.17-60, No.18-30 and No.18-60 (i.e., samples with the addition of photosensitive compounds), in the area of the first DTG maximum only the presence of ions \(m/z=17\), 18 was recorded. Taking this into account and the fact that the second DTG maximum exceeds 200 \({}^{\circ}\)C and, additionally, the fact that conversion value of double bonds is at the level of 100% (Table 3), we expect that these are the best materials from the polymer optical fiber-technology point of view. As in the case of samples with 33 wt.% NVP content, in the discussed series of samples, only at the proper decomposition temperature are ions indicating the decomposition of compounds containing benzene in their structure present. Residual mass for samples based on EB600 remains within the range of 9.8-16.9 wt.%. This value appears to decrease with increasing amounts of NVP added. In the next stage, detailed tests of the absorption and emission of the obtained compositions will be carried out. Below are photos (Figure 3) taken under an 8W UV lamp.