Layer-by-Layer crystallization of enantiomeric poly(lactide)s

Poly(lactide)s stereocomplex ultrathin film with controlled structure at a molecular level was able to be prepared by stepwise assembly using the stereocomplex interaction. Pure stereocomplex crystal can be easily obtained by using this technique. When the substrates pre-coated with the stereocomplex assembly were immersed into solution of poly(L-lactide) or poly(D-lactide) for a long time, each polymer was homogeneously deposited on the substrates. The enantiomer was epitaxially crystallized on the stereocomplex film. The XRD pattern of the films showed similar characteristic peaks of the stereocomplex, indicating that the crystallization was influenced by conformation of polymer at the substrate. This is the first case of the epitaxially growth of polymers on the structurally regulated surface. These films had high degree of crystallinity although the assemblies did not undergo a crystallization process. This method was considered to be a general method that can be applied to other polymers, which able to form stereocomplex.