The ring-opening polymerization (ROP) of trimethylene carbonate (TMC) using a base-acid binary organocatalyst system of 7-methyl-1,5,7-triazabicyclo[4.4.0]dec-5-ene (MTBD) and Brønsted acid trifluoromethanesulfonic acid (TFA) with benzyl alcohol (BnOH) as the initiator has been investigated. The MTBD and its conjugate-acid pair H-bonding bifunctional synergistic activation mechanism was demonstrated by NMR measurements, and the living/controlled nature of MTBD/TFA catalyzed ROP of TMC was confirmed by the kinetic and chain extension experiments. The controlled ROP of TMC with the optimal molar ratio of MTBD/TFA = 2/1 proceeded to afford well-defined PTMC with narrow molecular weight distributions (M w /M n ∼ 1.1). The molecular weights determined by 1 H NMR are in precise agreement with the theoretical values. 1 H NMR, SEC, and MALDI-ToF MS measurements confirmed the structure of the obtained homopolymer PTMC. In addition, a diblock copolymer consisting of poly(trimethylene carbonate) and poly(L-lactide) (PTMC-b-PLLA) was synthesized successfully by the MTBD/TFA binary catalyst system.
The ring-opening polymerization (ROP) of trimethylene carbonate (TMC) using imidodiphosphoric acid (IDPA) as the organocatalyst and benzyl alcohol (BnOH) as the initiator has been investigated. The polymerization proceeded without decarboxylation to afford poly(trimethylene carbonate) (PTMiC) with controlled molecular weight and narrow polydispersity. 1 H NMR, SEC, and MALDI-TOF MS measurements of the obtained PTMC clearly indicated the quantitative incorporation of the initiator at the chain end. The controlled/living nature for the IDPA-catalyzed ROP of TMC was confirmed by the kinetic and chain extension experiments. A bifunctional activation mechanism was proposed for IDPA catalysis based on NMR and FTIR studies. Additionally, 1,3-propanediol, 1,1,1-trimethy-lolpropane, and pentaerythritol were used as di-ol, tri-, and tetra-ol initiators, producing the telechelic or star-shaped polycarbonates with narrow polydispersity indices. The welldefined diblock copolymers, poly(trimethylene carbonate)block-poly(d-valerolactone) and poly(trimethylene carbonate)block-poly(e-caprolactone), have been successfully synthesized by using the IDPA catalysis system.
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