Investigation on sintering behavior of polylactic acid nanoparticles: A molecular dynamics simulation

QK Liu and ZY Wang and XH Zhu and Z Chen and KH Huang and WK Wu and HK Du, COMPUTATIONAL MATERIALS SCIENCE, 251, 113760 (2025).

DOI: 10.1016/j.commatsci.2025.113760

Polylactic acid (PLA) is an important polymer material in the medical field. The PLA products prepared by selective laser sintering (SLS) are widely used. This study employs all-atom molecular dynamics simulations to investigate the sintering behavior of PLA nanoparticles during SLS process. The potential energy, atomic morphology, average displacement, atomic distribution, and radius of gyration are analyzed to reveal the dynamic sintering process. The sintering process of PLA nanoparticles is divided into three stages: the approaching of nanoparticles initiated by van der Waals force, the formation and growth of sintering neck driven by surface diffusion and nanoparticles rotation, the fusion of sintering interface facilitated by molecular chain movement. An in-depth analysis of molecular chain behavior reveals that the small loops on the surface demonstrate high mobility. The small loops drive the migration of other molecular fragments through intra-chain coupling. This process facilitates the diffusion of molecular chains within PLA nanoparticles. The surface end-group aggregation of PLA chains is associated with the electrostatic potential of end-group atoms. The rotation of PLA nanoparticles is due to the aggregation of surface end-group atoms. The hydrogen bonds of end-group atoms in the aggregation region are helpful in improving the stability and performance of the PLA nanoparticles.

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