Sustainable Synthesis of Biomass-Derived C8 Monomers for Closed-Loop Recyclable and Biodegradable Polyesters

Area of Science:

• Polymer Chemistry
• Sustainable Materials Science
• Green Chemistry

Background:

• Fully biomass-based plastics are crucial for sustainable development but face challenges in monomer synthesis.
• Limited availability of suitable monomers hinders the creation of high-performance, recyclable, and biodegradable polymers.
• Developing efficient routes to long-chain monomers from renewable feedstocks is essential.

Purpose of the Study:

• To develop a sustainable synthesis pathway for suberic acid, a key C8 α,ω-dicarboxylic acid, from biomass-derived precursors.
• To produce additional C8 monomers, 8-hydroxyoctanoic acid and 1,8-octanediol, from suberic acid.
• To synthesize and evaluate polyesters (PHO and POS) derived from these monomers for their properties, recyclability, and biodegradability.

Main Methods:

• Sequential Knoevenagel condensation and hydrodeoxygenation of biomass-derived acids using Pd/HZSM-5 and MoOx/TiO2 catalysts to synthesize suberic acid.
• Hydrogenation of suberic acid on CoOx catalyst to yield 8-hydroxyoctanoic acid and 1,8-octanediol.
• Melt polycondensation of synthesized monomers to produce poly(8-hydroxyoctanoate) (PHO) and poly(octylene suberate) (POS).

Main Results:

• Achieved high yields for suberic acid (85.5%), 8-hydroxyoctanoic acid (89.5%), and 1,8-octanediol (92.8%) from renewable feedstocks.
• Synthesized PHO and POS polyesters with thermal and mechanical properties comparable to low-density polyethylene.
• Demonstrated excellent closed-loop chemical recyclability (∼95%) and biodegradability (∼87%) for both polyesters.

Conclusions:

• Established a viable strategy for synthesizing long-chain α,ω-dicarboxylic acids and related monomers from renewable resources.
• Developed high-performance polyesters (PHO and POS) with full life-cycle sustainability, including recyclability and biodegradability.
• Advanced the field of sustainable polymers by providing a practical route to monomers for advanced materials.