Selective Ring‐Opening Polymerization of Non‐Strained γ‐Butyrolactone Catalyzed by A Cyclic Trimeric Phosphazene Base

Abstract

A new superbase, the cyclic trimeric phosphazene base (CTPB), was prepared with high yield and purity. In the presence of alcohol, the CTPB serves as a highly efficient organocatalyst for ring-opening polymerization of the "non-polymerizable" γ-butyrolactone to offer well-defined poly(γ-butyrolactone) with high conversions (up to 98 %) at -60 °C. The produced polymers have high molecular weights (up to 22.9 kg mol ) and low polydispersity distributions (1.27-1.50). NMR analysis of initiation process and the structural analysis of resulting polymers by MALDI-TOF suggest a mechanism involving an activating initiator which leads only to linear polymers with BnO/H chain ends.

Selective Ring‐Opening Polymerization of Non‐Strained γ‐Butyrolactone Catalyzed by A Cyclic Trimeric Phosphazene Base

“…b) Abstracting the proton of the monomer to form amonomeric anion. Forthe X-ray structure [20] the thermal ellipsoids are shown at 50 %p robability.…”

“…Forthe X-ray structure [20] the thermal ellipsoids are shown at 50 %p robability. In the presence of BnOH, CTPB was highly efficient in ROPo faseries of cyclic monomers, including the non-polymerizable g-BL, with high conversions.…”

Effects of Chain Ends on Thermal and Mechanical Properties and Recyclability of Poly(γ‐butyrolactone)

“…Significantly, the resulting P γ BL can exhibit either a linear or cyclic topology, controlled by the catalyst/initiator nature and ratio, and it can be depolymerized back to its monomer completely by heating the bulk material at 220 °C (for linear P γ BL) or 300 °C (for cyclic P γ BL) for 1 h. Subsequently, effective organopolymerization of γ ‐BL was also achieved later with tetrameric phosphazene superbase t Bu‐P 4 as the initiator or catalyst (in combination with benzyl alcohol, BnOH, as the initiator), producing linear P γ BL with M n up to 26.7 kg mol −1 . Most recently, Liu, Li, and co‐workers also produced linear P γ BL with M n up to 22.9 kg mol −1 using a new cyclic trimeric phosphazene base and BnOH as the initiator …”

Living Coordination Polymerization of a Six‐Five Bicyclic Lactone to Produce Completely Recyclable Polyester

“…Chemically recyclable polymers [1][2][3][4][5][6][7][8][9][10][11][12] have attracted increasing attention in recent years because they allow for recovery of the building block chemicals via depolymerization or creative repurposing through generation of value-added materials,t hus offering af easible solution to the end-of-use issue of polymeric materials and providing ac losed-loop approach towards ac ircular materials economy. [13] However, three key challenges still remain before this approach becomes technologically and economically competitive: energy input, depolymerization selectivity,a nd depolymerizability/performance tradeoff.…”