Boosting Highly Ordered Porosity in Lanthanum Metal-Organic Frameworks for Ring-Opening Polymerization of γ-Butyrolactone

Abstract

<h2>Summary</h2> γ-butyrolactone (γ-BL), serving as the monomer of biocompatible and recyclable poly(γ-butyrolactone) plastic, faces a giant challenge in ring-opening polymerization (ROP) due to its low strain energy. The ROP of γ-BL is generally achieved under harsh conditions (e.g., high-pressure or gas-protected atmosphere) and is mostly based on homogeneous systems. Here, we synthesize a series of lanthanum metal-organic framework-based porous nanospheres and successfully apply them as heterogeneous catalysts in efficient ROP of γ-BL under mild conditions. Specifically, NNU-mIM-3 presents a yield of 24.6% with low polydispersity distribution centered at 3.6 kDa and the obtained PγBL can be completely and quantitatively recycled into monomers by simple heat treatment. Besides, the ROP catalysis systems have been intensively explored with various imine-based additives, proven to exhibit largely improved performance with PγBL yield of ~50% and Mw of ~8 kDa. This work paves a new way to explore novel heterogeneous catalysts in producing biocompatible and degradable plastics.