The homopolymerization in basic conditions of the recently reported bis(γ-lactone), 2H-HBO-HBO, is herein described for the first time. The solvent-free polymerization of this pentafunctional levoglucosenone (LGO) derivative affords fully renewable poly(vinyl-ether lactone) copolymers with a highly hyperbranched structure. This investigation stems from the polycondensation trials between 2H-HBO-HBO and di(methyl carbonate) isosorbide (DCI) that fails to give the anticipated polycarbonates. Such unexpected behavior is ascribed to the higher reactivity of the 2H-HBO-HBO hydroxy groups toward its α,β-conjugated endocyclic C═C, rather than the DCI methylcarbonate moieties. The different mechanistic scenarios involved in 2H-HBO-HBO homopolymerization are addressed and a possible structure of poly(2H-HBO-HBO) is suggested. Furthermore, the readily accessible (S)-γ-hydroxymethyl-α,β-butenolide (HBO) is also polymerized for the first time at a relatively large scale, without any prior modification, resulting in a new hyperbranched polymer with an environmental factor (E factor) ≈0. These new HBO-based polymers have a great potential for industrial-scale production due to their interesting properties and easy preparation via a low-cost, green, and efficient process.
Keywords: HBO; green polymerization; hyperbranched materials; levoglucosenone; renewable polymers.
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