Polyacrylonitrile Flower-Like Particles with Tunable Size and Morphology via Scalable Oxygen-Tolerant Polymerization

Polyacrylonitrile flower-like particles (PANFs), as hierarchical superstructures, have recently found applications in catalysis, batteries, sensing, and gas absorption. Yet, precise control over their size and morphology, which dictate their properties, remains challenging, as the role of reaction parameters in their formation is not well understood. Additionally, the production of PANFs can be challenging due to the current reaction conditions, such as polymerization under inert atmosphere in superheated solvents, especially when a higher scale is required. Here, we address these gaps in two directions. First, we establish how systematic control of key parameters─reaction temperature, initiator type and concentration, and solvent composition─enables predictable tuning of PANF dimensions and surface features. Second, we simplify the reaction by developing a low-temperature, oxygen-tolerant polymerization, which allows the preparation of PANFs without the need for any specialized equipment. As a result, we were able to control the key morphological parameters such as particle diameter, petal density, and petal roughness. By employing different initiators and polymerization temperatures, we were able to produce PANFs with tunable size over an order of magnitude (∼100-1300 nm). Petal density, roughness, and structural complexity were tuned over a wide range by initiator concentration, monomer conversion, solvent mixtures, and oxygen content, which emerged as a key parameter influencing both particle size and morphology. Finally, we establish a one-step, scalable, oxygen-tolerant protocol that enables safe, low-temperature PANF production with near-quantitative yield under ambient conditions. This study provides insights into PANF formation, introduces practical tools for morphological control, and delivers a robust platform for the scalable synthesis of complex polymer architectures.