Oxygen-Tolerant Inverse Microemulsion and Miniemulsion PhotoATRP

Reversible deactivation radical polymerization (RDRP) in an emulsion is a practical and environmentally friendly route to well-defined polymer synthesis. However, most emulsion RDRP has focused on conventional oil-in-water systems, restricting accessible materials to hydrophobic polymers. Here, we report the first example of a highly efficient and oxygen-tolerant inverse microemulsion and miniemulsion photoinduced ATRP (photoATRP) facilitated by a dual catalytic system. Irradiation with red light efficiently excites the photocatalyst methylene blue (MB⁺), facilitating the photoreduction of the deactivator to initiate and mediate polymerization. This process enables the precise synthesis of polymers with a controlled molecular weight, low dispersity (Đ ≤ 1.20), excellent chain-end fidelity, and temporal control. The versatility of this approach was further demonstrated by expanding the photocatalyst scope beyond MB⁺ to include a library of other water-soluble PC. This method was also successfully extended to the inverse miniemulsion. This work establishes a practical inverse emulsion photoATRP for synthesizing well-defined hydrophilic polymers.