Anionic ring-opening polymerization of a 5-membered cyclic carbonate with a myo-inositol structure

Abstract

Five-membered cyclic carbonate 5 was synthesized from myo-inositol via a four-step reaction. The structures of the obtained single crystals of 5 were investigated via X-ray structural analysis. The results showed that 5 has torsional and angular strains similar to those of previously reported 5-membered carbonates that undergo ring-opening polymerization. However, the anionic homopolymerization of 5 did not produce any polymeric products. On the other hand, the copolymerization of 5 with some lactones yielded polymeric products. Among the lactones used, ε-caprolactone (CL) produced a homogeneous mixture with 5 at a mole fraction of 5 (f5) up to 30 mol%. The copolymerization of the homogeneous mixtures produced copolymers with a mole fraction of 5 (F5) similar to that of f5. The glass transition temperature (Tg) of the copolymers was determined by a differential scanning calorimetory (DSC). The copolymer with F5 = 0.14 had a Tg of −26.1 °C, which increased with increasing F5 and reached a value of 0.65 °C at F5 = 0.29. 5-membered cyclic carbonate (5) was synthesized via 4-steps from myo-inositol which is mainly contained from grains. X-ray crystallographic analysis of 5 showed that 5 is largely twisted compared to non-polymerizable ethylene carbonate. However, the homopolymerization of 1 did not proceed. The copolymerization of 5 with CL, on the other hand, proceeded successfully to yield methanol-insoluble products. By changing the feed ratio, the content of 5 in the resulting copolymers increased up to 29%.