TiO₂ nanohelices (NHs) have attracted extensive attention owing to their high aspect ratio, excellent flexibility, elasticity, and optical properties, which endow promising performances in a vast range of vital fields, such as optics, electronics, and micro/nanodevices. However, preparing rigid TiO₂ nanowires (TiO₂ NWs) into spatially anisotropic helical structures remains a challenge. Here, a pressure-induced hydrothermal strategy was designed to assemble individual TiO₂ NWs into a DNA-like helical structure, in which a Teflon block was placed in an autoclave liner to regulate system pressure and simulate a cell-rich environment. The synthesized TiO₂ NHs of 50 nm in diameter and 5–7 mm in length approximately were intertwined into nanohelix bundles (TiO₂ NHBs) with a diameter of 20 μm and then assembled into vertical TiO₂ nanohelix arrays (NHAs). Theoretical calculations further confirmed that straight TiO₂ NWs prefer to convert into helical conformations with minimal entropy (S) and free energy (F) for continuous growth in a confined space. The excellent elastic properties exhibit great potential for applications in flexible devices or buffer materials.

中文翻译：

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压力诱导水热法制备 TiO2 纳米螺旋阵列及其弹性性能

TiO ₂纳米螺旋（NHs）由于其高纵横比、优异的柔韧性、弹性和光学特性而引起了广泛的关注，在光学、电子和微/纳米器件等广泛的重要领域具有广阔的应用前景。然而，将刚性TiO ₂纳米线（TiO ₂ NWs）制备成空间各向异性的螺旋结构仍然是一个挑战。在这里，设计了一种压力诱导的水热策略，将单个 TiO ₂纳米线组装成类似 DNA 的螺旋结构，其中将特氟龙块放置在高压釜内衬中以调节系统压力并模拟富含细胞的环境。合成的TiO ₂直径为 50 nm、长度约为 5-7 mm 的 NHs 缠绕成直径为 20 μm 的纳米螺旋束（TiO ₂ NHBs），然后组装成垂直的 TiO ₂纳米螺旋阵列（NHA）。理论计算进一步证实，直的 TiO ₂纳米线更喜欢转化为具有最小熵 ( S ) 和自由能 ( F ) 的螺旋构象，以便在有限空间内连续生长。优异的弹性性能在柔性器件或缓冲材料中具有巨大的应用潜力。