Diphenyl Phosphate as an Efficient Acidic Organocatalyst for Controlled/Living Ring-Opening Polymerization of Trimethylene Carbonates Leading to Block, End-Functionalized, and Macrocyclic Polycarbonates

The ring-opening polymerization (ROP) of cyclic carbonates with diphenyl phosphate (DPP) as the organocatalyst and 3-phenyl-1-propanol (PPA) as the initiator has been studied using trimethylene carbonate (TMC), 5,5-dimethyl-1,3-dioxan-2-one, 5,5-dibromomethyl-1,3-dioxan-2-one, 5-benzyloxy-1,3-dioxan-2-one, 5-methyl-5-allyloxycarbonyl-1,3-dioxan-2-one, and 5-methyl-5-propargyloxycarbonyl-1,3-dioxan-2-one. All the polymerizations proceeded without backbiting, decarboxylation, and transesterification reactions to afford polycarbonates having narrow polydispersity indices. In addition, 6-azido-1-hexanol, propargyl alcohol, and N-(2-hydroxyethyl)maleimide were used as functional initiators for the DPP-catalyzed ROP to produce the end-functionalized poly(trimethylene carbonate)s. For further modification of the azido end-functionlized polycarbonate, the macrocyclic poly(trimethylene carbonate) was synthesized by the intramolecular click cyclization of the α-azido, ω-ethynyl poly(trimethylene carbonate). The DPP...