Functionalized Interfaces for Hybrid Photocatalytic Materials

• Diego Castillo-Mora, Chemistry, University of Puerto Rico- Río Piedras Campus

• Christian Pester, Materials Science and Engineering, University of Delaware

Photocatalytic materials have garnered significant attention as greener alternatives to harmful reagents, particularly heterogeneous photocatalysts, as they simplify post-reaction purification processes. One effective method to immobilize these materials onto surfaces involves the functionalization of the surface with photocatalysts in the form of polymer brushes. However, the conditions required for optimal surface functionalization remain underexplored. The current procedure for grafting chain transfer agents onto a SiO₂ surface requires a minimum of 40 hours, which is not ideal for efficient applications. Additionally, the effects of surface roughness—controlled by glass etching duration—and light irradiance at the ends of SiO₂ optical fibers have not been sufficiently addressed, despite their potential influence on photocatalytic performance. In this study, our primary objective is to optimize the grafting procedure and establish the relationship between surface roughness and light irradiance for both unfunctionalized and functionalized fibers. We aim to determine the optimal grafting conditions through water contact angle measurements, using plasma-treated glass slides as model substrates. Furthermore, we seek to identify an ideal etching time and surface roughness that maximize light irradiance along the entire optical fiber. Lastly, we intend to replicate a procedure for synthesizing fluorescein O-acrylate, our chosen photocatalyst. To investigate these variables, 6 cm glass fibers were etched for varying durations using a hydrofluoric acid-based commercial etching cream. Optical microscopy was employed to qualitatively assess surface morphology, while optical profilometry was used to quantify surface roughness by averaging height variations. Optical power monitoring was used to measure the light irradiance emitted from the end of the optical fiber.