Master thesis: Computational study of biodegradable polymers with applications in 3D printing

The document is a Master thesis presented and defended in July 2025 within the Master in Nanoscience and Materials Technology of University of Cádiz, Spain Abstract: This work presents a detailed computational study on polylactic acid (PLA), a biodegradable polymer that has gained significant relevance in areas such as 3D printing and sustainable packaging. Thanks to its renewable origin and processing versatility, PLA is positioned as a fundamental material in the search for more sustainable solutions. However, many of its thermal and mechanical properties largely depend on structural characteristics like the molecular weight and stereochemistry of its chains, which highlights the importance of thoroughly understanding the structure-property relationship. To address this complexity, this study conducted a systematic analysis based on molecular dynamics simulations, focused on examining the glass transition temperature (Tg), a crucial property in polymer behavior. For this, a force field specifically adapted to accurately represent PLA homopolymers and copolymers was chosen, allowing for the investigation of the influence of molecular weight and stereochemical composition. Six different systems were modeled, and cooling processes were performed at various rates, applying two methods for Tg analysis and extrapolating the results for comparison with recent experimental data. The obtained results show that there are differences in thermal behavior depending on the system type. For L-type homopolymers, the Tg depends on chain size in accordance with theoretical predictions. For copolymers and D-type homopolymers, the results align reasonably well with the Flory-Fox equation, indicating that systems, which also contain the D monomer, have a lower Tg than L-type homopolymers. This approach has allowed for the validation of the used methodology and a more precise alignment of theoretical results with experimental values, which reinforces the importance of computational studies for investigating and predicting the behavior of complex materials. In summary, this work not only enriches our fundamental understanding of PLA but also offers essential tools for the rational design of biodegradable polymers with optimized properties for industrial use.