## 2 Materials and Methods  
### Synthesis and Characterization of Photoactive Polymers  
The photoactive polymeric materials used as photosensizers in this research are based on the procedure first described by [PERSON] [39], where Rose Bengal is covalently anchored to chloromethylalytrenic resins. The hydrophilic properties of the new materials are achieved by introducing two hydrophilic functional groups into the polymer matrix: ethylenediamine and \(\gamma\)-gluconolactone, according to the work first described by [PERSON] [40]. The experimental procedure for the synthesis of these polymers is described in detail in the previously described work [19]. Below is a summary of the polymer preparation procedure. The synthesis of these materials consists of several stages. In the first stage, the copolymerization between p-chloromethylstyrene (CME, monomer) and p-divinylbenzene (DVB, crosslinking agent) is carried out. In a subsequent stage, starting from this synthesized polymer (P1), Rose Bengal is anchored in the polymer matrix (P2), and finally, systems that impart hydrophilicity, such as ethylenediamine and \(\gamma\)-gluconolactone (\(\gamma\)-GL), are incorporated with the aim of developing photoactive polymeric materials for application in aqueous media (P3 and P4). The polymer P1 (composed of CME and DVB) is not photoactive, as it lacks RB in its polymer matrix. In contrast, P2, P3, and P4, which do contain covalently bound RB in their structure, can be used as supported polymeric photocatalysts. The structural difference between them is based on the incorporation of ethylenediamine (P3 and P4) and \(\gamma\)-gluconolactone (P4). All commercially available reagents and solvents were used: p-chloromethylstyrene (Sigma, Burlington, MA, USA, 90%), divinylbenzene (DVB; Fluka, Buchs, Switzerland, \(\sim\)80% mixture of isomers; the residual is composed mainly of 1.3- and 1,4-ethylstyrene isomers), 2,2\({}^{\prime}\)-azobis(isobutyronitrile) (AlBN; Sigma, \(\geq\)98.0%), Rose Bengal sodium salt (Fluka), tetrabutylammonium hydroxide solution \(\sim\)25% in MeOH (\(\sim\)0.8 M) (TBAOH solution; Fluka), ethylenediamine (Sigma, \(\geq\)99%), \(\gamma\)-gluconolactone (Sigma, \(\geq\)99%), 9,10-anthracenediproionic acid (ADPA; Aldrich, Burlington, MA, USA, \(\geq\)98.0%), 2-furoic acid (Merck, Rahway, NJ, USA, \(\geq\)99%), 1-dodecanol (Aldrich, 98%), tetrahydrofuran (Scharlab, Barcelona, Spain, synthesis grade), ethyl acetate (Scharlab, synthesis grade), ethanol (Scharlab, 96%), methanol (Scharlab, synthesis grade), methanol (Scharlab, spectroscopy grade), 1,4-dioxane (Panreac, Barcelona, Spain, spectroscopy grade), toluene (Scharlab, synthesis grade) and N,N\({}^{\prime}\)-dimethylformamide (treated previously with anhydrous MgSO\({}_{4}\)). For this research, the complete characterization of the materials was replicated [19]. The polymer characterization process consists of three stages. The first stage corresponds to the study of the polymerization process, which has been carried out through characterization by FT-IR spectroscopy, FT-Raman spectroscopy, and TGA of the polymer matrices. The second part involves the study of the optical properties of the polymers due to the covalent anchoring of RB to the matrix. This study has been conducted using UV-Vis absorption spectroscopy, fluorescence emission, and excitation spectroscopy, the determination of the amount of RB in the polymer matrix, and the determination of the particle size of the polymers using granulometric analysis techniques and scanning electron microscopy (SEM). All these procedures are described in more detail in the previous work [19]. Finally, the characterization section involves the ability to generate singlet oxygen. The singlet oxygen generation capacity of the materials was determined by analyzing the photo-oxidation kinetics of anthracene-9,10-dipropionic acid (ADPA) in Milli-Q water. For each polymer, 40 mg of the photosensitizer was added to 10 mL of the ADPA solution (1.2 \(\times\) 10\({}^{-4}\) M) in a test tube.