A novel observation in anionic ring-opening polymerization behavior of cyclic carbonates having aromatic substituents

摘要

The anionic ring-opening polymerization of six-membered cyclic carbonates having aromatic substituents, 5-methyl-5-phenyl-1,3-dioxan-2-one (1) and 5,5-diphenyl-1,3-dioxan-2-one (2), was carried out. The anionic homopolymerization of 1 readily proceeds to afford the corresponding polycarbonate, while 2 showed only a slight homopolymerizability. This is due to a rapid back biting reaction of the propagating polymer end to form 2. The conformational restriction of the adduct of 2 with an alkoxide, originating from the electrostatic repulsion between the alkoxide anion and the pi electrons of the aromatic rings, might cause the rapid back biting reaction. The anionic copolymerization of 2 with 5,5-dimethyl-1,3-dioxan-2-one (3) proceeds to afford the copolymer. The anionic ring-opening polymerization of 1 was confirmed to be an equilibrium polymerization. Monomer 1 was regenerated up to the equilibrium monomer concentration by depolymerization of poly(1). A volume expansion (10.8%) was observed during the polymerization of 1. [References: 34]