11:00 AM - 11:15 AM
▼ [17a-D511-7] Manipulating superelastic and ferroelastic deformation by cocrystal designing with the choice of coformers: crystal packing and thermal diffusivity analysis
Keywords:Superelasticity, Ferroelasticity, Thermal diffusivity
Organic molecular crystals are now considered the next-generation structural materials, owing to the discovery of unique mechanical deformation behaviors such as superelasticity, ferroelasticity, shape memory effect, etc. Understanding the structure-property link behind mechanical deformations such as superelasticity and ferroelasticity is critical for realizing the potential applications of such organic crystals. In our recent study, we have found that weak dispersive interactions in the crystal lattice such as CH---F play a key role in obtaining the shape-memory effect in the crystals of 1, 2-bis(4-pyridyl)ethane dodecafluorosuberate with amplified forward stress values. In line with this study, we studied the mechanical deformation of two cocrystals synthesized with parent compound (1,4-Diiodotetrafluorobenzene (IFB)) and with coformers (1,2-Bis(4-pyridyl)ethane (BPE) and Pyrene (PYE), referred to as 1 and 2, respectively. Further, heat transfer properties were investigated by thermal diffusivity measurement using microscale temperature-wave analysis (μ-TWA). The parent compound 1,4-Diiodotetrafluorobenzene was chosen due to the plausible presence of CH---F interactions in its cocrystals. The two cocrystals (1 & 2) exhibited distinct mechanical deformations, superelasticity, and ferroelasticity respectively. 1 and 2 by single crystal X-ray diffraction and energy framework analysis, revealed that both deformations occurred via mechanical twinning with a difference in molecular orientation. From the energy framework analysis, the percentage of H---F interactions and total interaction energy was more in cocrystal 1 than 2. In addition, measured thermal diffusivity was higher in cocrystal 1 than in 2.