DIRECT EVIDENCE FOR UV SHIELDING AND PHOTOCATALYSIS IN PMMA COMPOSITES CONTAINING TITANIUM DIOXIDE AND ZINC OXIDE

Poly(methyl methacrylate) (PMMA) is a transparent and processable support for titanium dioxide and zinc oxide, but evidence of UV shielding, aqueous photocatalysis and self-cleaning is required individually. The literature cutoff date for this structured critical review was 25 August, 2026. This structured critical review presents 50 identified reports of directly tested PMMA-containing specimens. Studies are classified by architecture, and evaluated for illumination, controls, endpoint validity, normalisation, uncertainty, material integrity, etc. High visible transmission and UV attenuation can still be achieved with low loadings of nanocomposites and thin coatings. Porous, fibrous and surface-exposed formats favour reactant access and recoverable water treatment instead often at the expense of optical clarity. The published disappearance constants do not allow a general ranking of TiO2 versus ZnO due to variations in reactor geometry, concentration, catalyst basis and illumination. The performance of hybrid composites depends on the formulation. The activity of ZnO/PMMA is improved with intermediate Ag deposition but decreases with higher deposition. The reduced apparent optical edge and filler co-presence are not enough evidence of visible-light activity or interfacial charge transfer. Similarly, dye decolorization and contact angle change are not representative of mineralisation and deposited soil removal respectively. The main requirement remaining is to simultaneously validate optical function, contaminant removal and polymer preservation on a single specimen. An integrated compact reporting framework includes total and direct transmission, haze, controlled photocatalysis, repeated cleaning, adhesion, release and weathering. Transparent UV shields and recoverable photocatalytic supports are directly evidenced; durable photocatalytic self-cleaning is not yet sufficiently demonstrated in the identified corpus.