Ring-opening Alternating Copolymerization of Epoxides with Dihydrocoumarin Catalyzed by Phosphazenium/Et3B Binary Catalytic System
The ring-opening alternating copolymerization(ROAC)of 3,4-dihydrocoumarin(DHC)with various epoxides was successfully achieved using a binary catalytic system consisting of tri[tris(dimethylamino)phosphora-nylidenamino]phosphonium chloride(P4+Cl‒)and triethylborane(TEB).The impact of polymerization temperature and catalyst loading on the catalytic activity and selectivity of ROAC was investigated.The P4+Cl‒/TEB catalytic system was found to be highly efficient and controlled in the ROAC process,preventing the intramolecular transesteri-fication.This results in polyesters with high alternating structures,controlled molecular weights,and preserved functional groups fidelity.The effectiveness of the catalyst system is supported by kinetic investigations,proton nuclear magnetic resonance(1H NMR)and size exclusion chromatography(SEC)spectra,as well as matrix-assisted laser desorption/ionization-time of flight-mass spectrometry(MALDI-TOF-MS)analysis.
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