Cooling runs of poly(lactic acid) for estimation of glass transition temperature

Atomistic simulations of poly(lactic acid) and its stereoisomers of different molecular weights. The preparation of the systems is described elsewhere [1]. The dataset contains cooling runs of different cooling velocities for each system. The label PLLA denotes a system with only L-type of monomers, the label PDLA denotes a system with only D-type of monomers and the label copo100 is used for compolymer systems with 100 monomers per chain of both types. The percentage of D monomer in each copolymer is indicated in the label (55% and 16%). The cooling was performed from 500K to 200K. The last frames of the publicly available trajectories were used as the initial configurations for the simulations.[2] The cooling velocity can be calculated as 300K/(length of the simulation). The density from the runs can be analyzed to estimate the glass transition temperature as a function of cooling velocity. This procedure has been a part of a Master thesis presented and defended in July 2025 by Sheintly Díaz González within the Master in Nanoscience and Materials Technology of University of Cádiz, Spain.[3] All files are in Gromacs format. The used force field parameters are summarized in PLAFF3.itp file in each directory. The force field was based on ref[4] and it was modified to be able to simulate copolymer structures. Namely, the tabulated potential for the backbone dihedrals was replaced by the Ryckaert-Bellemans function, which has the same parameters for both types of monomers. In addition, a new atom type was created for the D-type of monomer, to be able to properly distinguish CMAP parameters for each type of monomer. [1] Bačová, P; Harmandaris, V.; Molina, S. I.; Macromolecules 2025 58 (16), 8572-8580, https://pubs.acs.org/doi/10.1021/acs.macromol.5c00918 [2] Bacova, P., Harmandaris, V., & Molina, S. I. (2025). MD simulations of poly(lactic acid) chains of various molecular weights in melt [Data set]. Zenodo. https://doi.org/10.5281/zenodo.17186105 [3] Díaz González, S., Molina, S. I., & Bacova, P. (2025). Master thesis: Computational study of biodegradable polymers with applications in 3D printing. Zenodo. https://doi.org/10.5281/zenodo.17257117 [4] McAliley, J. H.; Bruce, D. A. Development of Force Field Parameters for Molecular Simulation of Polylactide. Journal of Chemical Theory and Computation 2011, 7, 3756–3767, DOI: 10.1021/ct200251x