Anisotropic microfibres of a liquid-crystalline diketopyrrolopyrrole by self-assembly-assisted electrospinning†
Electrospinning is a well-established technique for the preparation of nanofibres from polymer solution or melt, however it is rarely applied for small molecules. Here we report a unique example of a liquid-crystalline (LC) diketopyrrolopyrrole (DPP) dye that was successfully used for electrospinning. Micrometric fibres with anisotropic alignment of DPP dye were produced by this process as shown by polarized optical microscopy and selected area electron diffraction. This newly designed DPP dye self-assembles in solution by hydrogen bonding and π–π-interactions and forms columnar LC phases in the bulk. X-ray scattering and polarized FT-IR studies in the LC state revealed a hierarchical arrangement of DPP molecules into columnar structures. The successful preparation of anisotropic microfibers by electrospinning is attributed to the hydrogen bond-directed supramolecular polymerization of the new DPP dye in solution and its LC properties.