Diclofenac-Derived Organotin(IV) Complexes as Efficient Photostabilizers for Poly(vinyl chloride) Films Under UV Irradiation

This study reports the synthesis and evaluation of diclofenac-derived organotin(IV) complexes as photostabilizing additives for poly(vinyl chloride) (PVC). Diclofenac was selected as a ligand due to its aromatic structure and heteroatom-rich framework, enabling the formation of stable tin-based complexes with potential UV-absorbing and radical-scavenging properties. The synthesized di- and tri-organotin complexes were incorporated into PVC films at 0.5 wt.% and exposed to UV irradiation (365 nm) for up to 300 h to assess their stabilizing efficiency. Photodegradation was monitored by tracking changes in carbonyl, polyene, and hydroxyl indices, as well as weight loss and surface deterioration. Compared with blank PVC and ligand-containing films, the organotin-modified samples exhibited significantly slower growth of degradation indices, reduced mass loss, and improved surface integrity after irradiation. Among the evaluated additives, the tributyltin complex demonstrated the highest photostabilizing performance, showing superior retention of chlorine content and lower surface roughness parameters. Overall, the results indicate that diclofenac-based organotin(IV) complexes are effective photostabilizers for PVC, with the tributyltin derivative emerging as the most promising candidate for enhancing the durability of PVC materials under UV exposure.