Organic crystals with two-dimensional bending and manually twistable properties for flexible optical waveguides

Most organic crystals are brittle, which greatly restricts their applications in flexible smart materials. Herein, we reported two multi-flexible organic crystals. One of them exhibits two-dimensional (2D) elasticity, while the other one exhibits dual plasticity and elasticity along different directions. Their brittle polymorphs were also prepared to establish the correlations of the structure-property of flexible organic crystals from the perspective of crystal engineering. These flexible crystals can be manually twisted without fracture. Therefore, it was verified that manually twisted crystals can also be prepared from 1D plastic and elastic crystals, which has not been reported before. Detailed crystallographic analyses, energy framework calculations and nanoindentation tests were used to reveal the mechanism of the multiple mechanical responses of these crystals. It was found that these properties can be ascribed to the large differences in strength and orientation between the intermolecular interactions, together with the unique molecular arrangement in the crystals. Finally, the application of these flexible crystalline materials in the field of the optical waveguide was developed.

Automated summary

In this study, two multi-flexible organic crystals were reported, one exhibiting two-dimensional elasticity and the other exhibiting dual plasticity and elasticity along different directions. Correlations between the structure-property of flexible organic crystals were established by preparing brittle polymorphs. It was discovered that manually twisted crystals can be prepared from 1D plastic and elastic crystals. Detailed crystallographic analyses, energy framework calculations, and nanoindentation tests were used to reveal the mechanism of the multiple mechanical responses of these crystals. These flexible crystalline materials were also applied in the field of optical waveguides.