A Temperature-Transferable Coarse-Grained Model for Poly(lactic Acid) Melts

We
present a temperature-transferable coarse-grained (CG) model
for poly(lactic acid) (PLA), specifically designed to replicate its
volumetric properties and solubility parameter in the molten state.
The CG-bonded potentials were derived by using the iterative Boltzmann
inversion (IBI) optimization method to match structural properties
from detailed atomistic models. A parametrization workflow was employed
to determine nonbonded interaction parameters with temperature-dependent
corrections that provide agreement with the target properties across
the melting temperature range. The CG model successfully replicates
key features of the PLA melt. It satisfactory reproduces the density
and solubility parameter, maintains the dependence of chain conformation
on molecular weight, and captures the dynamic behavior through agreement
in scaled mean squared displacement and diffusion coefficients with
the atomistic model. Additionally, the CG model offers much faster
equilibration compared with the atomistic model. The proposed model
is expected to be particularly useful for investigating the miscibility
characteristics of PLA in various blends and composites that remain
challenging to explore using fully atomistic simulations or experiments.