Development of Tertiaryamino Squaramide Bifunctional Organocatalyst for Controlled/Living Ring Opening Polymerization of Lactide

A series of tertiaryamino squaramide bifunctional organocatalysts carrying different alkyl groups were synthesized and further applied to the ring opening polymerization of L-lactide (LLA). The formed poly (LLA)s exhibit narrow polydispersity and high end-group fidelity featuring a living polymerization process. A linear evolution of Mn with monomer conversion with uniform polydispersity, the observed first order kinetics of the monomer consumption, and the linear dependence of (M/I) with poly(LLA) molecular weights point at controlled/living nature of the polymerization. The MALDI-ToF MS spectra showed one series of distribution corresponding to the potassium-charged poly(LLA) with a single benzyl end group with an exclusive spacing of 144 Da that perfectly matched with the molecular weight of LLA and confirming the end-group fidelity. Details of aminosquaramides preparation, their structure-activity relationship towards ROP, kinetic measurements and chain-extension experiments will be discussed