Photoinduced healable hybrids based on anthracene-containing silsesquioxane nanoparticles.

[Display omitted] • Photoinduced healing of organic–inorganic hybrids were achieved by employing the photocyclization reaction. • Anthracene unit covalently linked with silsesquioxane nanoparticles (SQ) was employed as a cross-linking site. • UV (365 nm) irradiation of SQs led to the formation of photoresponsive solid hybrids with cross-linked structures. • The repair of surface scratches on the hybrid film was achieved by irradiation with deep UV light (265 nm). The photoinduced healing of organic–inorganic hybrids, originating from spatiotemporal (cross-linked and non-cross-linked) control of the physical properties by reversible photodimerization of anthracene units covalently linked to silsesquioxane nanoparticles (SQ-NPs), was explored. Ultraviolet (UV) irradiation (365 nm) of multifunctional SQ-NPs, with a 9-anthracene unit and a long alkyl group on each chain, induced photodimerization of the anthracene units, resulting in cross-linking of the photoresponsive SQ-NPs. Monomerization of the cross-linked hybrid films was induced by irradiation with deep ultraviolet light (265 nm), enabling the healing of surface scratches by fluidizing non-cross-linked viscous states. The intermolecular bonding (dimerization) and debonding (monomerization) endowed the organic–inorganic hybrids with photoinduced healing properties. The reversible dimerization/monomerization of the anthracene units on the SQ-NPs was monitored by UV–vis and FT-IR measurements, suggesting fast and efficient healing/response features under an air environment at room temperature. [ABSTRACT FROM AUTHOR]