Poly(vinyl acetate-co-crotonic acid) from bio-based crotonic acid: synthesis, characterization and carbon footprint evaluation

The sludge from wastewater treatment systems (WWTS) contains a high quantity of organic material with great potential for synthesising bio-based chemicals and materials that can replace their fossil-based equivalents. Herein, we have investigated the upcycling of WWTS to the production of bio-based crotonic acid (CA), which is in turn used in replacement of the commercial, fossil-based CA in the copolymerization with vinyl acetate to poly(vinyl acetate-co-crotonic acid). The results demonstrate that a great benefit in terms of GHG emission reduction is obtained when the fossil-based synthesis is replaced with the WWTS-to-CA route, decreasing the carbon footprint of CA from 13.9 to 7.75 kg CO2 per kg CA. The copolymers constituted from fossil-based or bio-based CA have the same composition and thermal properties, independently of the origin and the purity of the starting CA monomer, suggesting their equivalency for the investigated application.