The effect of high-pressure on organocatalyzed ROP of γ-butyrolactone

High pressure as a novel tool for the cationic ROP of γ-butyrolactone

“…12 . This finding seems to be in agreement with the literature data reported for PGBL homopolymers, 13,35 including our own previous studies, 17 which clearly show that the temperature range of observed T m depends on the polymer structures. Note that melting temperatures of cyclic and linear polymers were observed to be located at lower ( T m ∼323 K) and higher temperature range, T m ∼333 K, respectively.…”

“…Moreover, for PTSA-catalyzed reactions, there is a clear increase in dispersity as the polymerization time gets longer, which is consistent with the results of our group's previous study concerning TBD-mediated ROP of GBL. 17 Mentioned results clearly indicated that by simple extension of the reaction time, we were able to modify the properties of the obtained polymers ( e.g. , increase the dispersity and number of the macrocyclic form).…”

“…, crystallization), viscosity and solubility changes that can dramatically affect the polymerization pathway and, hence the properties of the produced polymers. 17 Our recent studies concerning the high-pressure ROP of CL and GBL have clearly shown that at elevated pressure, the I st order transition (crystallization) had a significant impact on the progress of the reaction since it is considered as a competitive process to polymerization. 31 Briefly, since temperatures of phase transitions (including crystallization) generally increases with compression, one has to be careful in selecting thermodynamic conditions of polymerization to avoid undesired crystallization of solvent/monomer that suppresses the progress of reactions.…”

“…However, both these affect the crystallization and viscosity increased, which may be minimized/eliminated in diffusion-controlled processes by using solvents of low transfer constant or conducting the reaction at higher temperature and lower pressure regimes, respectively. Notably, in a previous paper that discussed the TBD-catalyzed ROP of GBL, 17 we were able to find optimal thermodynamic conditions and avoid the GBL crystallization by real-time monitoring of the polymerization progress using Broadband Dielectric Spectroscopy (BDS). We observed that for TBD-catalyzed GBL ROP performed in toluene, GBL had revealed a tendency of crystallization at low temperatures (below 248 K) and high pressure values (above 1300 MPa).…”

Unique Superbase TBD (1,5,7-Triazabicyclo[4.4.0]dec-5-ene): From Catalytic Activity and One-Pot Synthesis to Broader Application in Industrial Chemistry

“…TBD is widely used as a catalyst for transesterification reactions. , It is regarded as the most effective catalyst for the production of polyesters by alcohol-induced ring-opening polymerization (ROP) and copolymerization of lactide, lactones and cyclic carbonates (Scheme ). ,− The enhanced catalytic activity of TBD relative to N -methyl TBD (MTBD), , DBU, ,,, and DBN was attributed to its bifunctionality, ,,, enabling the simultaneous activation of both the carbonyl monomer and the alcohol. Moreover, it was found that TBD is able to replace the broadly used metallic catalyst Sn­(II) 2-ethylhexanoate [Sn­(Oct) 2 ].…”