Ultrafast Aqueous Photoinduced Electron/Energy Transfer Reversible Addition–Fragmentation Chain Transfer Polymerization-Induced Self-Assembly: Wavelength-Dependent Morphologies and Scalable Nanoparticle Preparation

Abstract Photoinduced electron/energy transfer–reversible addition–fragmentation chain transfer (PET-RAFT) polymerization offers a powerful route to oxygen-tolerant polymer synthesis under visible light, yet slow polymerization rates remain a persistent bottleneck for further development. Here, we report an aryloxy xanthate chain transfer agent (CTA) bearing a 2-naphthyloxy Z group that unlocks ultrafast aqueous PET-RAFT polymerization under orange light irradiation. The system achieves an apparent propagation rate constant (kpapp) of 0.89 min–1, reaching high monomer conversion (>80%) within 2 min while maintaining good control over polymerization (Đ ≤ 1.2). Density functional theory (DFT) calculations indicate that the enhanced polymerization rate originates from the low fragmentation energy barrier of the CTA anionic radical. Leveraging this performance, we applied the system to photoinduced polymerization-induced self-assembly (photo-PISA), achieving ultrafast formation of well-defined polymeric nanoparticles within 1 min without prior deoxygenation and with tunable morphologies accessible by varying formulation conditions. Strikingly, photo-PISA exhibited a pronounced wavelength dependence: long-wavelength irradiation produced well-defined vesicles, whereas short-wavelength irradiation yielded irregular aggregates. This behavior is attributed to superior light penetration and spatial uniformity at longer wavelengths, establishing wavelength-tunable light-field uniformity as a handle for the accessible PISA morphology. These findings establish the 2-naphthyloxy xanthate CTA as a versatile platform for scalable and high-throughput photo-PISA, opening new avenues for the rapid and oxygen-tolerant fabrication of functional polymeric nanomaterials.