Exploring the Potentialof High Molar Mass Poly(hydroxymethylfuroate):Synthesis, Properties, and Recyclability Studies

The synthesis of the fully furan-based high-molar-mass poly(hydroxymethylfuroate) (<b>HMM-PHMF</b>) is herein presented along with the investigation of thermal properties, filmability, water contact angle (WCA), and recyclability. The polymer (<i>M</i>_n > 200000 g mol^–1) has been produced on a multigram scale by N-heterocyclic carbene (NHC)-promoted chain extension of <b>PHMF</b> (1 h, 190 °C), which can be directly synthesized from 5-(hydroxymethyl)furfural (<b>HMF</b>) or 5-hydroxymethyl-2-furancarboxylic acid (<b>HMFCA</b>). The polyester is thermally highly stable up to 280 °C, showing a semicrystalline behavior with <i>T</i>_m ∼ 194 °C when processed from solvent and an amorphous character with <i>T</i>_g ∼ 90 °C when processed from the melt. <b>HMM-PHMF</b> has been efficiently filmed by compression molding and submitted to WCA analyses (86 ± 2°), behaving as a potential biobased food packaging material. Finally, recyclability has been assessed through alkaline hydrolysis producing <b>HMFCA</b> and cyclodepolymerization affording the starting hydroxymethylfuroate macrocyclic oligoesters <i><b>c</b></i><b>(HMF)</b>_<b>n</b>, which can be converted again through entropically driven ring-opening polymerization (ED-ROP), in a closed-loop cycle.