Room Temperature Synthesis and Photopatterning of Mesoporous Titanium Dioxide Thin Films

ABSTRACT We report a photochemical strategy for fabricating mesoporous TiO 2 thin films that combines deep‐UV (193 nm) photolithography with block copolymer (BCP) self‐assembly. This dual top‐down/bottom‐up approach enables direct patterning and mineralization at room temperature, without thermal annealing, offering a scalable and energy‐efficient alternative to conventional sol–gel processing. By tailoring the BCP concentration, titanium‐to‐ethylene oxide molar ratio, and polymer architecture, we achieved highly uniform mesoporous monolayers with tunable pore size and film thickness. FTIR and SEM analyses confirm the selective degradation of the PS and PEO blocks under UV exposure. Notably, the PEO degradation is significantly enhanced in the presence of titanium oxo‐clusters, attributed to the photocatalytic activity of the Ti precursor under DUV irradiation. We further demonstrate spatially controlled structuring via photolithographic masks, enabling micro‐ and nanopatterned oxide films with hierarchical architectures. This method allows for precise control over both porosity and lateral geometry, expanding the design space for functional oxide coatings. Our findings open new avenues for the fabrication of advanced hierarchical TiO 2 ‐based materials for applications in photonics, sensing, and nanotechnology, while contributing to the broader development of low‐temperature, light‐assisted material processing.