Synthesis of polymorpholine-2,5-dione-block-polylactide by two-step anionic ring-opening polymerization

摘要

Polymorpholine-2,5-dione-block-polylactide (PMD-b-PLA) was synthesized via two-step anionic ring-opening polymerization at room temperature. First step of ring-opening polymerization was the ring-opening of mor-pholine-2,5-dione (MD). It was carried out in an airtight and dry polymerization tube using potassium ethoxide/THF (0.2M/L) as an initiator for 90 min. Then lactide was ring-opened in THF solution by the potassium alcoholate of PMD. From the FTIR of the copolymer, we can find all the peaks in PLA and PMD. The ~1H-NMR of copolymer gave us a proof to the principle of the anionic ring-opening polymerization and the fraction of PMD in the copolymer was calculated as 86.3%. DSC analysis of copolymer indicated that it was a copolymer with one T _g (63.6°C) and two T_ms (155.6 and 171.4°C) instead of a mixture of PMD and PLA. The yields of the PMD and the copolymer were 32 and 26%, respectively.