Presentation Information
[23p-21B-12]Anisotropic thermal diffusivity correlation in organosuperelastic and organoferroelastic molecular crystals
〇(DC)Subham Ranjan1, Meguya Ryu2, Ryota Morioka3, Satoshi Takamizawa1, Junko Morikawa3 (1.Yokohama City Univ., 2.National Metrology Inst., 3.Tokyo Institute of Tech.)
Keywords:
Thermal diffusivity,Superelasticity,Ferroelasticity
The findings of diffusionless reversible mechanical deformation behaviors such as superelasticity (SE) and ferroelasticity (FE) in organic molecular crystals have attracted much attention as next-generation structural materials. Organic molecular crystals with such properties are potential candidates for thermal management applications in miniaturized compliant optoelectronic devices. Hence, it is of fundamental importance to understand the anisotropic thermal transport properties such as thermal diffusivity and its relationship with structure in organosuperelastic and organoferroelastic crystals. In this work, we investigated the relationship between crystal structure and anisotropic thermal diffusivity in three organic crystals with different mechanical behaviors. The single crystals of trans-3-hexenedioic acid (1) exhibited two-directional FE, while the other two crystals were cocrystals, synthesized with (1,2-Bis(4-pyridyl)ethane and 1,4-Diiodotetrafluorobenzene) (2), and (pyrene and 1,4-Diiodotetrafluorobenzene) (3), which showed SE and FE, respectively. The single-crystal structure was comprehensively investigated by single-crystal X-ray diffraction and energy framework analysis. It revealed that the SE and FE deformations were facilitated by mechanical twinning with different molecular orientations in each deformation. The crystals 1, 2, and 3 exhibited anisotropic thermal diffusivity values, which could be correlated to the intermolecular interactions in the respective directions. Thermal diffusivity was lowest along weak dispersive interactions such as C-H...O interactions and π...π interactions in crystal 1 and 3 (Fig. 1). In contrast, in crystal 1 and 2, it was higher along the strong interactions such as electrostatically dominated O-H...O hydrogen bonds and C-I...N halogen bonds, respectively. Furthermore, the thermal diffusivity was higher in the orthogonal direction of deformation stress.