Recoverable Fluorination Accelerates Ring‐Opening Copolymerisation and Enables Post‐Polymerisation‐Modification of Polyesters

Abstract Fluorination of polymers is a powerful strategy to enhance chemical or material properties yet integrating these benefits into degradable polymers remains underexplored. Here, we report a new class of fluorinated polyesters synthesized via ring‐opening copolymerisation of pentafluoro styrene oxide with phthalic anhydride. The pendant C 6 F 5 groups accelerate catalysis through fluorine‐specific π‐stacking interactions and improve obtained molecular weights compared to the non‐fluorinated variant giving access to high weight materials ( M n,max. > 100 kg mol −1 ) with thermal and mechanical properties competitive with commodity plastics. These C 6 F 5 groups then act as reactive handles in the material for efficient post‐polymerisation modification (PPM) in solution, allowing fine‐tuning of thermal, mechanical, optical, and solubility properties. PPM can even be performed on material surfaces, films and fibres can be selectively modified without dissolution. Lastly, degradation enables quantitative recovery of fluorine centres as sodium fluoride, offering a sustainable end‐of‐life option for the incorporated fluorine. Our work demonstrates how targeted fluorination of degradable polyesters can simultaneously enhance catalysis and unlock advanced material functionality.