Compositionally modulated phase in crystalline n-alkane mixtures -: art. no. 050701

We report an x-ray scattering study of the compositionally modulated microphase separated state (mu PSS) of binary n-alkane (C23H48:C28H58) mixtures. By employing a quenching technique, we obtained many orders of sharp lamellar and superlattice reflections. The mu PSS is a regular superstructure consisting of pure C-23 layers, and layers rich in C-28 but containing up to similar to 14% C-23 Plus voids, A monolayer of the minority component regularly alternates with one or more layers of the majority. The mechanism for thermodynamic stability of the mu PSS may be related to the entropy associated with longitudinal displacements of the molecules.