Atomistic Simulation\nof Amorphous Poly(Lactic Acid)\nBlends: Stereodependent Miscibility and Properties

A series of amorphous bidisperse poly(lactic acid) systems\ncontaining\ntwo types of linear chains in different ratios, with different chain\nlengths and enantiomeric compositions, have been simulated by the\nmolecular dynamics method, and their structural, thermophysical, and\nmechanical properties have been studied and compared with those of\namorphous poly(L-lactic acid). The calculated average segregation\nparameter, the pair correlation function, and the accessible surface\narea of the components reveal that the effective local intermixing\nof the chains worsens only with the addition of the alternating poly(LD-lactic acid) chains with the same degree of polymerization.\nIn all other cases, it becomes better. The blend characteristics change\nmonotonically as the fraction of the shorter chains increases and\ncan demonstrate more complex behavior in blends of chains with the\nsame length. The effect of stereodependent miscibility, i.e., the\nchange in local miscibility of polymer chains due to their different\nstereoisomeric states, has been discovered and described. The results\nobtained may be useful for the production of poly(L-lactic\nacid) with the desired properties.