Definitive support by transmission electron microscopy, electron diffraction, and electron density maps for the formation of a BCC lattice from poly{N-[3,4,5-tris(n-dodecan-l-yloxy)benzoyl]ethyleneimine}

Transmission electron microscopy (TEM), electron diffraction (ED), and electron density maps (EDM) experiments were carried out on a poly-{N-[3,4,5-tris(n-dodecan-l-yloxy)benzoyl]-ethyleneimine} {poly[(3,4,5)12G1-Oxz]} with a degree of polymerization (DP) of 20. All experiments confirmed the thermotropic body-centered cubic (BCC) Im3m lattice suggested previously by X-ray diffraction (XRD) experiments. The unit cell parameter determined by ED at 23°C is a=42.4 Å, in good agreement with XRD results which show a= 42.6 Å after quenching from 70°C. EDM of the XRD results confirm that the supramolecular minidendrimer obtained from poly[(3,4,5)12G1-Oxz] adopts a spherical "inverse micellar-like" structure, with the polyethyleneimine backbone and the aromatic groups microsegregated and concentrated in the corners and in the center of the cubic unit cell. A space-filling continuum is realized by the n-alkyl groups that radiate out of the aromatic core of the spherical dendrimer. This manuscript is only the second example of complete structural analysis of a lattice generated from supramolecular objects and complements the previous example reported from our laboratory on the Pm3n lattice.