Expanding the Chemical Space of Cyclic Polyphthalaldehyde via Post‐Functionalization

Cyclic polyphthalaldehydes (cPPAs) are hydrophobic cyclic polymers with stimuli-responsive depolymerization property. The introduction of hydrophilic functionalities to cPPAs is challenging due to the intrinsic limitation of cationic polymerization. Herein, we developed a post-functionalization approach to achieve water-soluble cPPA derivatives with high molecular weight. The cPPA modified with cell-penetrating oligoarginine underwent cellular uptake via endocytosis and acid-triggered depolymerization in lysosome, which provided new potential for biological application.