ESR2 will study the contribution of biodegradable polymers as sources of MP. This knowledge will be used to develop novel biodegradable polymer formulations for the substitution of conventional materials creating MP or leaching toxic chemicals. The novel formulations will be biodegradable, and have mechanical and thermal properties similar to existing polymers. Post-polymerization modifications with different functional groups and copolymerisation with appropriate bio-based monomers will provide systematic tailor-made samples with different hydrophilicity-hydrophobicity ratios, compositions, and crystallinities to balance physical properties and degradability. To compare the material properties and environmental impact, the polymers will be processed to different forms and the bulk properties and environmental degradability of the novel and traditional biodegradable polymers will be established and evaluated. The new polymers provided by ESR2 will be used as reference material for the verification of the analytical methods and toxicity studies in WP2. ESR2 will cooperate closely with all groups working on the identification of MP in ecosystems.