Random Copolymerization of ε-Caprolactone and L-Lactide by Ring Opening Polymerization Using a Co/N-Doped Carbon Framework as Catalyst

The synthesis and use of MOF-derived Co/NCF (N-doped carbon framework) material as a heterogeneous catalyst for copolymers synthesis via ring-opening polymerization (ROP) are reported for the first time. The Co/NCF material is applied for the copolymerization of L-lactides (LA) and epsilon-caprolactone (epsilon-CL) as monomers via ROP in bulk without any solvent or co-catalyst. The as-prepared catalyst is characterized using XRD, TPD, XPS, SEM, and TEM analytical techniques. At the same time, H-1 and C-13-NMR spectroscopy were used to analyze the microstructure of the copolymer confirming the random copolymer structure. The average r values calculated from the heterodiad analysis of the H-1 NMR, data were r(LA) = 0.96 and r(CL) = 0.93 and L value calculated from the triads analysis of C-13 NMR, data were L-LA = 3.17 and L-CL = 2.79, respectively. It has been observed that the melting temperature and glass transition temperature of the copolymer increases with higher LA content. The XRD and DSC analyses also confirmed that the as-synthesized copolymer possesses two phases corresponding to the polylactide and polycaprolactone, respectively. Additionally, the activity of Co/NCF is also compared with other Co-based heterogeneous catalysts to demonstrate its ability.

Automated summary

The synthesis and use of MOF-derived Co/NCF material as a heterogeneous catalyst for copolymers synthesis via ring-opening polymerization (ROP) have been reported for the first time. The Co/NCF material is applied for copolymerization of L-lactides (LA) and epsilon-caprolactone (epsilon-CL) as monomers via ROP in bulk without any solvent or co-catalyst, confirmed by various analytical techniques. Additionally, the copolymer structure was verified through spectroscopic analysis and it was observed that the melting and glass transition temperatures increased with higher LA content, while possessing two phases corresponding to polylactide and polycaprolactone.