Chem-biotech strategy to synthesize sustainable urethane-based polymers and additives from microbially produced hydroxyalkanoyloxy-alkanoates and polyol lipids

• Chem-biotech strategies for building sustainable (macro)molecular structures. • Bioproduction of hydroxyalkanoyloxy-alkanoates, and polyol lipids synthons. • Polyol structure significantly influences the final architecture and properties. • Synthesized HAA-based polyurethanes present high performances. • Plasticizers based on HAAs and PL enhance the softness and elasticity of polymers. Combining biotechnology and chemistry strategies seems to be one of the main drivers to develop innovative and sustainable macromolecular architectures for the next decades, starting from renewable carbon sources, such as biomass and plastic wastes. Herein, microbially produced biobased precursors, namely esterified 3-(3-hydroxyalkanoyloxy)alkanoates (HAAs), averagely comprised of ten carbons each fatty acid, and polyol lipids (PL) mainly structured with 3,5-dihydroxydecanoic acids connected to a mannitol head group as the largest fraction (78 %), have been used as building blocks to synthesize different urethane-based polymers and plasticizers as a proof of concept of this global approach. Polyurethanes (PU) were elaborated using HAAs and PL as chain extenders and then processed as films. The structure of these polyester-polyols significantly impacted the resulting properties. The hard segments (HS) on HAA-based PUs slightly increases from 40 to 46 % and the asymmetrical disposal of aliphatic chains hindered regular organization, making all samples fully amorphous. Conversely, the chain’s entanglement benefited network cohesion. In contrast, chemically crosslinked PL-based PU can be processed as films with superior mechanical properties, despite having lower HS (33 %). Additionally, plasticizers based on HAAs, and PL significantly increased the flexibility and elasticity of polyvinyl chloride (PVC). These findings suggest that such sustainable polyester-polyols offer valuable potential for developing sustainable PUs, meeting the requirements of a circular (bio)economy.