Supraparticles from Titania Nanoplates: Assembly, Photocatalytic Polymer Encapsulation, Functionalization, and Multifunctional Hybrid Supraparticles

This study presents the assembly of titania nanoplates (TNPs) into three‐dimensional supraparticles (SPs) via an emulsion‐based assembly technique using dodecyltrimethylammonium bromide (DTAB) as surfactant. The SPs have diameters ranging from ∼100 to ∼400 nm and are encapsulated within a polystyrene shell. The encapsulation is achieved through surface‐initiated photocatalyzed radical polymerization (UVP), utilizing the intrinsic photocatalytic activity of the TNPs. By varying the duration of UV light ( λ = 365 nm) exposure, the overall organic fraction of the polymer can be tuned. Small‐angle X‐ray scattering (SAXS) measurements indicate a higher degree of order within the SPs after the polymerization and increased interparticle distances between the encapsulated TNPs. Presumably, the polymerization initiates at the double bond of the native oleylamine ligands on the TNP surface, resulting in surface‐grafting of the polymer and re‐ordering of the TNPs within the encapsulated SPs. Furthermore, the functionalization of the polymer shell with carboxylic acid or azide groups is demonstrated. As a proof‐of‐concept, TNPs were assembled with superparamagnetic iron oxide nanocubes (SPIONs) to form hybrid SPs. The UVP could be easily adapted to these hybrid SPs, resulting in encapsulated TNP/SPION‐based SPs that combine the optical and magnetic properties of both materials.