Function-driven design and processing of degradable polyesters

Adhering to green chemistry’s principles and the sustainability development goals, polyesters are a promising class of polymers in the prospect of overcoming the challenges of conventional plastics. Monomers employed for their synthesis can be derived from renewable feedstock and aliphatic polyesters are able to degrade generating harmless products. Biobased and/or degradable polyesters represent indeed one segment of the bioplastic market. If properly designed, they can find widespread applications such as packaging holding a key role in EU’s strategy for plastics in a circular economy.¹
Design issues need to be addressed to broaden the limited range of thermal and mechanical properties, introduce functionalities and program the degradation profile to fit the application scope. In this effort, polyesters with different microstructures have been developed through ring-opening copolymerization to afford structural diversity and tune the material’s properties and degradation rate.^2,3 The design of the structure at the macromolecular level, through careful monomer selection and sequence regulation, enabled control over the final properties of the material and the degradation kinetics. To tackle the inability of further chemical manipulation of aliphatic polyesters, thiol functional monomers and biobased, unsaturated macrolactones have also been employed as monomers.^5,6 Besides the design of the primary structure, the control of how the structure develops during melt processing is crucial to tune the desired functions, mechanical properties’ profile and degradation rate. This is of outmost importance in view of a large-scale production and real application of polyesters. By regulating the composition of the copolymer and processing parameters at industrial scale, the service lifetime of polyester fibres could be prolonged while ensuring a fast erosion rate. The understanding of the effect of the processing parameters on polyesters’ properties gave also directions on how to overcome the lack of thermal stability and therefore, balance degradability and processability for this class of materials. Building on this knowledge, thermoplastic copolymers, now commercially available, have been designed and proved to exhibit a faster degradation rate than poly(e-caprolactone) and a comparable thermal stability during melt processing.⁴ To truly advance towards sustainable alternatives, the a priori design, the processing and the overall performance of polyesters should, however, be considered in a broader scope and a circular way. A balance has to be reached between less carbon footprint raw materials, recyclability, degradability and performance.

(1) European Commission, A European Strategy for Plastics in a Circular Economy 2018; (2) A. Meduri, T. Fuoco, M. Lamberti, C. Pellecchia, D. Pappalardo, Macromolecules 2014, 47, 534; (3) T. Fuoco, T. Mathisen, A. Finne-Wistrand, Biomacromolecules 2019, 20, 1346; (4) T. Fuoco, A. Finne-Wistrand, Biomacromolecules 2019, 20, 3171; (5) (a) Aliphatic poly(esters) with thiol pendant groups US: Id 15/768347; (b) T. Fuoco, A. Finne-Wistrand, D. Pappalardo, Biomacromolecules 2019, 17, 1383; (c) T. Fuoco, D. Pappalardo, A. Finne-Wistrand, Macromolecules 2017, 50, 7052; (6) T. Fuoco, A. Meduri, M. Lamberti, V. Venditto, C. Pellecchia, D. Pappalardo, Polym. Chem. 2015, 6, 1727; (7) T. Fuoco, T. Mathisen, A. Finne-Wistrand, Polym. Degrad. Stabil. 2019, 163, 43-51.

Bio: Tiziana Fuoco is currently a researcher in Polymer Technology at KTH Royal Institute of Technology, Sweden.
She was born in Salerno, Italy, in 1986. She graduated with honours in Chemistry at University of Salerno in 2012 and received a PhD’s degree in Polymer Chemistry from the same University in 2016. Right after, she held a two-year postdoctoral research position in Polymer Technology at KTH Royal Institute of Technology and in 2018 was appointed as researcher. Her research field is Polymer Science; her activity is focused on the rational design of the degradable polymers, mainly aliphatic polyesters, to endow functionalitiesand performance addressing newapplication needs.Tiziana Fuoco is co-author of 22 peer-reviewed scientific articles and she has been active in technology transfer: she is co-inventor of one granted patent and two patent applications; she is co-owner and co-founder of a start-up that produces and sells degradable, thermoplastic materials for 3D printing.