Rapid Ring-Opening Polymerization of γ-Butyrolactone toward High-Molecular-Weight Poly (γ-butyrolactone) by an Organophosphazene Base and Bisurea Binary Catalyst

The low temperature condition, long reaction time and associated high energy inputs involved in the polymerization process still hampered the scalable production of poly(gamma-butyrolactone) (P gamma BL) via ring-opening polymerization (ROP) of low strained gamma BL due to its unfavorable thermodynamics. In this contribution, we presented the rapid ROP of gamma BL using a bisurea in combination with an organophosphazene base as the binary catalyst. Well-defined P gamma BL samples with various terminal groups were prepared by using different alcohol initiators. The bisurea as a co-catalyst exhibited much higher catalytic activity even compared to the most active monourea in previous report as supported by the kinetic experiments. A moderate monomer conversion of 61% was achieved within 10 mins, producing high-molecular-weight P gamma BL with M-n up to 37.5 kDa and good mechanical properties. The short polymerization time considerably reduced the energy cost for the ROP of gamma BL conducted at low temperature condition. This study may clear away obstacles for the scalable production and practical applications for P gamma BL.

Automated summary

In this study, the rapid ring-opening polymerization (ROP) of gamma-butyrolactone (γ-BL) using a bisurea and an organophosphazene base as the binary catalyst was presented. Well-defined poly(gamma-butyrolactone) (P gamma BL) samples with various terminal groups were prepared, achieving a moderate monomer conversion of 61% within 10 mins and producing high-molecular-weight P gamma BL with M-n up to 37.5 kDa and good mechanical properties. The use of bisurea as a co-catalyst exhibited higher catalytic activity compared to previous monourea catalysts, significantly reducing the energy cost for the ROP of γ-BL conducted at low temperature condition. This study may overcome obstacles for the scalable production and practical applications of P gamma BL.