Study of the Mechanical and Thermal Properties of Poly(Lactic Acid) and Poly(Ethylene Glycol) Block Copolymer with Molecular Dynamics

Abstract

In this study, the mechanical properties and glass transition temperature of PLA-PEG block copolymer were investigated by molecular dynamic simulation. The software package Discover in Materials Studio with condensed-phase optimized molecular potentials for atomistic simulation studies (COMPASS) force field was used for the simulation. To verify the validity of simulation results, PLA and PLA-PEG copolymer were prepared in this research and the glass transition temperature was measured by DSC. The simulation results showed that the random combination chain has more probability than the alternating combination chain to exist in copolymer structure. Furthermore, PLA-PEG block copolymer has better tensile strength but lower shear strength than PLA, which agree well with the theoretical results. The simulation values of Tg (PLA: 333.97 K and PLA-PEG: 326.70 K) agree well with the DSC results (PLA: 328.8 K and PLA-PEG: 321.3 K). The conclusion could be drawn from the results that molecular dynamic simulation (MDS) is a potential method for investigating the structure, mechanical properties, and glass transition temperature of PLA-PEG copolymer and may be used for other polymers and copolymers.