Talk: Effect of Stereoisomerism on the Structure and Linear Rheology of Poly(Lactic Acid)

Oral contribution presented at 11th International Meeting of the Hellenic Society of Rheology (HSR 2025, https://mathweb.aegean.gr/hsr2025/) which took place in Syros, Greece, from 11th to 14th of June, 2025. Abstract: In an effort to satisfy the sustainability requirements, recent studies have increasingly focused on polymers of natural origin, such as poly(lactic acid) (PLA). Due to their complex, often protein-like structures with chiral centers, bio-based polymers pose significant challenges for computational modeling as well as for systematic experimental studies. In this work we combine experimental and computational approach in order to investigate how stereoisomerism affects the local structure and the final viscoelastic behavior of low molecular weight PLA in melt. Employing atomistic molecular dynamics simulations, we show subtle yet significant differences in chain packing of the L- and D- homochiral stereoisomers with respect to the copolymer chains of PDLLA. [1] In order to reach the ultimate goal of elucidating the structure-properties-perfomance relationship, the simulation data on local and terminal dynamics are complemented by experimental characterization using differential scanning calorimetry, gel permeation chromatography and linear rheology measurements. This integrated study aims to bridge molecular-level information with macroscopic performance, and by doing so to shed light on some possible causes of controversy in the vast literature on PLA-based materials. References: [1] P. Bačová, V. Harmandaris, S.I. Molina, Computational investigation of structural properties of poly(lactic acid) and its stereoisomers: shape, size and flexibility, Macromolecules, 2025 58 (16), 8572-8580 https://pubs.acs.org/doi/full/10.1021/acs.macromol.5c00918