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