Spontaneous Formation of Colloidal Crystals of PLA Stereocomplex Microspheres and their Hierarchical Structure

In this paper, the combined effect of the influence of polylactide (PLA) end-group nature and PLA architecture on the morphology of stereocomplexes formed during precipitation from organic solvent is investigated. Stereocomplexation of star-shaped poly(l-lactide) and linear poly(d-lactide) functionalized with imidazolium ionic liquid end groups in 1,4-dioxane leads to the formation of uniform microspheres, which are able to crystallize in the form of colloidal crystals. Microscopic scanning electron microscopy (SEM) and atomic force microscopy (AFM) analysis show the hierarchical structure of the system starting from the nanometrical grains composed of a few stereocomplex macromolecules that aggregate in uniform microspheres finally forming colloidal crystals of microspheres.