Flow Photochemistry for Single-Chain Polymer Nanoparticle Synthesis

Single chain polymer nanoparticles (SCNP) are an attractive polymer architecture that provides functions seen in folded biomacromolecules. The generation of SCNPs, however, is limited by the requirement of a high dilution chemical step, necessitating the use of large reactors to produce processable quantities of material. Herein, the chemical folding of macromolecules into SCNPs is achieved in both batch and flow photochemical processes by the previously described photodimerization of anthracene units in polymethylmethacrylate (100 kDa) under UV irradiation at 366 nm. When employing flow chemistry, the irradiation time is readily controlled by tuning the flow rates, allowing for the precise control over the intramolecular collapse process. The flow system provides a route at least four times more efficient for SCNP formation, reaching higher intramolecular cross-linking ratios five times faster than batch operation.