Acyclic Diene Metathesis (ADMET) Polymerization for the Synthesis of Chemically Recyclable Bio-Based Aliphatic Polyesters

The recent developments of the synthesis of bio-based long-chain aliphatic polyesters by the acyclic diene metathesis (ADMET) polymerization of alpha,omega-dienes, derived from plant oils and bio-based chemicals, like bis(10-undecenoate) with isosorbide, using ruthenium-carbene catalysts are reviewed. The development of subsequent (one-pot) tandem hydrogenation produced saturated polyesters under mild conditions. The polymerizations under bulk (without solvent, 80-90 degrees C) or in ionic liquids (50 degrees C) under vacuum conditions enabled the synthesis of high molar mass polymers (M-n > 30,000 g/mol). The polymerization performed by the molybdenum-alkylidene catalyst afforded the highest-molecular-weight polyesters (44,000-49,400 g/mol, in toluene at 25 degrees C) exhibiting promising tensile properties (strength and elongation at break) compared to polyethylene and polypropylene. Depolymerizations of these polyesters, including closed-loop chemical recycling, were also demonstrated. Catalyst developments (more active, under mild conditions) play a key role in the efficient synthesis of these materials.