3-D hexagonal close-packed nano-structure from self-organization of triblock copolymer containing lateral ethyl groups in the middle of rod segment

We report an unusual 3-D hexagonal supramolecular nano-structure via self-assembly of a coil-rod-coil molecule in the solid state. The rod-coil molecule consists of five biphenyls linked together with ether bonds as a rod segment, incorporating lateral ethyl groups in the center of the rod segment, and poly(propylene oxide) (PPO) with a degree of polymerization of 17 as coil segments. The molecular structure was characterized by 1 H NMR and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectroscopy. The self-assembling behavior of the molecule was investigated by means of differential scanning calorimetry, polarized optical microscopy and small angle X-ray scattering reveals that the lateral ethyl groups in the center of rod segment and the PPO coil segments strongly induce the molecule to self-assemble into the 3-D hexagonal close-packed nano-structure in the solid state.