Controllable Synthesis of Monodispersed Zirconia Submicrospheres Based on Oligomer Aggregation Mechanism for Enhanced Scattering Manipulation

Oxide submicrospheres with a high refractive index are essential for enhancing scattering and manipulating light transmission at submicrometer scale in photonic applications. However, achieving precise control over the diameter and monodispersity of transition metal oxide submicrospheres remains challenging, due to the unclear formation mechanism and lack of effective synthesis strategy. Here, a nonclassical mechanism of oligomer aggregation for controllable synthesis of monodispersed ZrO₂ submicrospheres (ZS) with mean diameters ranging from 0.263 to 1.295 µm and polydispersity indices almost below 0.1 is presented. Oligomers are identified as the fundamental building units, and their aggregation behavior governs the formation of ZS. Moreover, the precise regulation of homogeneous oligomer formation and aggregation is achieved through the introduction of alkanoic acids and amines. This adjustment, driven by steric effect, hydrogen bonding strength, reaction priority, and quantity, enables control over spherical morphology, monodispersity, and diameter. Compared to SiO₂ and polystyrene submicrospheres, ZS exhibits enhanced, tunable scattering behavior and superior chemical stability. The findings suggest that the oligomer aggregation mechanism, along with its controllable strategy, provides a new framework for synthesizing monodispersed transition metal oxide submicrospheres, broadening the range of materials available for photonic applications.