## 3 Results and Discussion  
### Synthesis and Characterization of Photoactive Polymers  
The complete synthesis and characterization of the materials were replicated according to the previous work [19], yielding the same results concerning the physical characterization (FT-IR, FT-Raman, particle size, SEM microscopy, etc.), the study of their optical properties (UV-Vis absorption spectroscopy, fluorescence spectroscopy) and the determination of the amount of Rose Bengal in the polymer matrix. In Figure 1, the synthesis process of each polymer, as well as the functional groups introduced into the structure, is illustrated.  
The following are the results obtained from the characterization of each photoactive material: P1: FT-IR (cm\({}^{-1}\)): 3018, 2917, 1629, 1425, 1265, 906, 795, 707. FT-Raman (cm\({}^{-1}\)): 3058, 2906, 1631, 1408, 1267, 1181, 1001. The decomposition temperature is 500-510 \({}^{\circ}\)C, and the average particle diameter is 24.2 \(\upmu\)m. P2: FT-IR (cm\({}^{-1}\)): 3020, 2920, 1625, 1453, 1266, 902, 794, 709. FT-Raman (cm\({}^{-1}\)): 3054, 2907, 1627, 1411, 1266, 1180, 1003. The decomposition temperature is 500-510 \({}^{\circ}\)C, UV-Vis absorption (\(\uplambda_{\text{max}}\), nm): 571, fluorescence emission (\(\uplambda_{\text{max}}\), nm): 602 (\(\uplambda_{\text{ex}}\) = 572 nm), Rose Bengal loading: 2 \(\upmu\)mol RB g\({}^{-1}\) resin, and the average particle diameter is 28.1 \(\upmu\)m. P3: FT-IR (cm\({}^{-1}\)): 3358, 3046, 2921, 1619, 1447, 990, 906, 798, 713. FT-Raman (cm\({}^{-1}\)): 3055, 2903, 1632, 1407, 1315, 1179, 1105, 1003, 803. The decomposition temperature is 500-510 \({}^{\circ}\)C, UV-Vis absorption (\(\uplambda_{\text{max}}\), nm): 561, fluorescence emission (\(\uplambda_{\text{max}}\), nm): 593 (\(\uplambda_{\text{ex}}\) = 564 nm), Rose Bengal loading: 2 \(\upmu\)mol RB g\({}^{-1}\) resin, and the average particle diameter is 24.5 \(\upmu\)m. P4: FT-IR (cm\({}^{-1}\)): 3367, 3056, 2928, 1628, 1451, 1081, 902, 804, 704. FT-Raman (cm\({}^{-1}\)): 3055, 2903, 1634, 1408, 1307, 1188, 1086, 1001, 930, 803. The decomposition temperature is 500-510 \({}^{\circ}\)C, UV-Vis absorption (\(\uplambda_{\text{max}}\), nm): 562, fluorescence emission (\(\uplambda_{\text{max}}\), nm): 591 (\(\uplambda_{\text{ex}}\) = 564 nm), Rose Bengal loading: 2 \(\upmu\)mol RB g\({}^{-1}\) resin, and the average particle diameter is 28.8 \(\upmu\)m.  
No leaching of Rose Bengal (RB) was observed in any of the polymers. Figure 2 presents the absorption spectra for polymers P2-P4, as well as RB in Milli-Q water solution. The absorption maxima for the polymeric materials are observed between 562 nm and 571 nm. These values are consistent with those previously obtained [19] and those reported in the literature for covalently anchored RB on sytrenic resins [41]. Although the absorption spectrum of RB-containing polymers is analogous to that of the dye in an aqueous solution, all polymers exhibit broader spectra compared to free Rose Bengal. Furthermore, the maximum absorption spectrum of the polymer matrices is shifted to higher wavelengths compared to free RB (\(\uplambda_{\text{max}}\) = 557 nm), with P3 and P4 between 561 and 562 nm and P2 at 571 nm.  
Finally, it should be noted that polymers P2-P4 proved to be efficient in generating singlet oxygen, as demonstrated by experiments conducted on the oxidation kinetics of ADPA. The results of the generation efficiency are presented in the following section.  
Figure 1: Chemical composition of polymers P1–P4 and their schematic synthesis process.