Microspheres from stereocomplexes of polylactides containing ionic liquid end-groups

Low-molecular-weight polymers of L- and D-lactide containing different end-groups (hydroxy, butoxy, trifluoromethoxy, heptafluorobutoxy, oxyethylimidazole groups, and groups derived from the imidazolium ionic liquid) are synthesized. It is shown that the nature of end-groups affects the stereocomplexation of corresponding pairs of polymers. Stereocomplex of poly(L-lactide) and poly(D-lactide) containing imidazolium ionic liquid end-groups (PLA-IL) precipitates from 1,4-dioxane solution in the form of monodisperse, perfectly spherical microspheres. Such behavior of PLA-IL, not observed for polymers containing other end-groups, can be attributed to the presence of strongly interacting ionic liquid end-groups. This conclusion is supported by the results of 1H NMR and dynamic light scattering experiments as well as by direct observation of precipitated particles by scanning electron microscopy.(c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012