Oxygen and carbon dioxide dual gas-responsive homopolymers and diblock copolymers synthesized via RAFT polymerization

Abstract

The monomer, 2,2,2-trifluoroethyl 3-(N-(2-(diethylamino)ethyl)acrylamido)propanoate (TF-DEAE-AM), which contains both O₂ and CO₂-responsive functionalities, was first synthesized from commercially available N,N-diethylethylenediamine, 2,2,2-trifluoroethyl acrylate, and acryloyl chloride. Subsequently, a series of dual-gas responsive polymers, poly(2,2,2-trifluoroethyl 3-(N-(2-(diethylamino)ethyl)acrylamido)propanoate) (poly(TF-DEAE-AM)) and poly(ethylene glycol)-b-poly(2,2,2-trifluoroethyl 3-(N-(2-(diethylamino)ethyl)acrylamido)propanoate) (PEG-b-poly(TF-DEAE-AM)), were synthesized by employing reversible addition–fragmentation chain transfer (RAFT) polymerization. Due to the protonation between CO₂ and DEAE groups, and the specific van der Waals interactions between O₂ and C–F bonds, micelles consisting of poly(TF-DEAE-AM) or PEG-b-poly(TF-DEAE-AM) display distinct CO₂ and O₂ responsiveness in aqueous media. Pyrene, which is a model hydrophobic drug, is able to be effectively encapsulated in the micelles based on PEG-b-poly(TF-DEAE-AM). It is found that the release of pyrene sharply increases after bubbling CO₂ or O₂ compared to N₂, and the release rate of the solution bubbling with CO₂ is the fastest. Since both CO₂ and O₂ are key gases for the human body, the CO₂- and O₂-induced release property of poly(TF-DEAE-AM) may open opportunities for the preparation of functional materials with special CO₂ and O₂ responsiveness for potential applications in biomedicine.