Self-assembled superlattices of polyamines in a columnar liquid crystal

We show that the principle of orthogonal self-assembly, which makes use of mutually noninterfering interactions, is generally applicable to create liquid crystalline (LC) superlattices of polyamines. The structure and phase behavior of mixtures of an acid-modified discotic (A-BTA) with branched and linear poly(ethylene imine) (b-PEI and l-PEI) and the linear organometallic polymer poly(ferrocenyl(3-ammoniumpropyl)methylsilane) (PFS) were investigated. All mixtures were studied by polarizing optical microscopy, differential scanning calorimetry, infrared spectroscopy and X-ray scattering. Mixtures of A-BTA with b-PEI form a disordered oblique columnar LC phase featuring separate columnar microdomains of the polymer as a result of orthogonal hydrogen bonding and ionic interactions. Branching stabilizes the superlattice structure, but l-PEI with a molecular weight up to 250 kDa and PFS can also be incorporated in the nanostructured LC. The results show that the LC superlattice can serve as a general platform to achieve nanostructured functional materials by using various functional polymers.