对层间分子排列的精确控制仍然面临重大挑战，其阻碍了新的热传递机制的发展和极端热性能的改善。
近日，中国科学技术大学吴长征教授等人在Science China Materials发表研究论文，通过有序分子设计（TaS2-Cn, n = 3, 6, 8, 12），在层状无机材料中实现了一系列链长增长的烷基胺分子的限域插层，并首次揭示了由S-Ta-S无机亚晶格和双层有序线性分子组成的新型层状有机-无机超晶格。
本文要点
1) 该超晶格材料具有超高的隔热性能，且随着层间插入的烷基链的长度增加，层间的烷基链变得更加有序和线性且扭转构象减少。2) 更线性和有序的分子构象降低了热导率。TaS2-C12的热导率为0.426 W m−1 K−1，仅为原始TaS2晶体的三分之一。这种超晶格结构设计为开发新的有机-无机功能材料和探索超低热导率材料提供了新的研究思路。Figure 1. (a) Schematics of TaS2 and TaS2-C12. A TaS2-Cn hybrid structure was synthesized through a one-step solvothermal method. (b) XRD patterns of TaS2, TaS2-C3, TaS2-C6, TaS2-C8, and TaS2-C12. (c) The interlayer spacings of TaS2, TaS2-C3, TaS2-C6, TaS2-C8, and TaS2-C12. Cross-sectional HAADF-STEM images of (d) TaS2, (e) TaS2-C3 and (f) TaS2-C12. Scale bar in (d–f), 2 nm.Figure 2. (a) FT-IR spectra of TaS2, TaS2-C3, TaS2-C6, TaS2-C8, and TaS2-C12. (b) SEM image of TaS2-C12 and elemental mapping images of Ta, S, C, and N. The inset shows the corresponding cross-sectional SEM image. Scale bar in (b), 50 μm; scale bar in the inset of (b), 10 μm. (c) The mass ratio of C element and the molar ratio of N:Ta in the TaS2 hybrid superlattice. (d) XPS spectra of S 2p of TaS2, TaS2-C3, TaS2-C6, TaS2-C8, and TaS2-C12. (e) N k-edge XANES spectra of TaS2-C3, TaS2-C6, TaS2-C8, and TaS2-C12.![]()
Figure 3. (a) E-space XAFS spectra of Ta L3-edge of TaS2, TaS2-C3, TaS2-C8, TaS2-C6 and TaS2-C12. (b) R-space XAFS of Ta L3-edge of TaS2, TaS2-C3, TaS2-C6, TaS2-C8 and TaS2-C12. (c) ppp-polarized SFG spectra of TaS2-Cn (n = 3, 6, 8, and 12), where the symbols represent experimental data and the solid lines are the fitted data. (d) Schematic of the relationship between the orientation of alkyl chains (θchain) and the terminal methyl group (θmethyl). (e) The relationship curve between the ratio of χ(2)CH3,ss/χ(2)CH2,ss and θmethyl. (f) The χ(2)CH3,ss/χ(2)CH2,ss ratio of the ppp-polarized SFG spectra is plotted against the alkyl chain length of the organic molecule. (g) Schematic of the alkyl chain stacking arrangement of the TaS2-Cn hybrid structure.![]()
Figure 4. (a) Temperature dependence of the total thermal conductivity of TaS2, TaS2-C3, TaS2-C6, TaS2-C8 and TaS2-C12. (b) Room temperature thermal conductivity of TaS2, TaS2-C3, TaS2-C6, TaS2-C8 and TaS2-C12. (c) Room temperature thermal conductivity plotted against the χ(2)CH3,ss/χ(2)CH2,ss ratio of the ppp-polarized SFG spectra. (d) Raman spectra of TaS2, TaS2-C3 and TaS2-C12. (e) Comparison of the sound velocity (νl, νt, νa) for the five samples. (f) Calculation of the elastic properties (E, G) of TaS2, TaS2-C3, TaS2-C6 TaS2-C8, and TaS2-C12.Chun Wang, Yang Liu, Renlong Zhu, Tianpei Zhou, Minghao Wang, Han Cheng, Wenjie Wang, Xiaolin Tai, Lin Wang, Long Chen, Yue Lin, Shuji Ye, Yi Xie, Changzheng Wu. New layered organic-inorganic superlattice with bilayer linear molecules for superhigh heat insulation. Sci. China Mater. (2024).https://doi.org/10.1007/s40843-024-3102-y
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