Nanoporous Silicon-Elastomer Hydrids: From Liquid-Crystalline Functionalization to a Tunable Elasticity Assessed by Laser Ulltrasonics

硅中的纳米孔隙率导致这种主流半导体在从纳米流体和生物传感器到药物递送、能量存储和光子学的众多领域中具有全新的功能。然而，弹性的难以评估极大地限制了其力学探索和应用至今。该项目的最终目标是将纳米多孔硅的应用进一步扩展到声子领域，并开发一种具有热和电可调弹性特性的新型混合纳米材料系统，可扩展到工业需求。实现这一目标的关键是将晶圆级纳米多孔硅与限制在其孔中的液晶弹性体相结合。为了全面表征和理解混合材料的弹性行为，我们建议利用现场激光超声和复杂的计算方法提供的无与伦比的见解。声学评估将使观察到许多效果成为可能：孔隙形态和孔隙度梯度方向对波传播的影响，类液体的可压缩性，粘弹性材料在有限空间和混合的可调弹性。通过补充先进的X射线衍射研究，我们将探索液晶弹性体的结构，限制的作用和不同刺激下的相行为。最终，这些见解将使我们能够微调材料设计和合成，以实现特定的温度和电刺激依赖的弹性特性，在微机电系统领域和新兴的声子领域具有潜在的应用。

Nanoporosity in silicon leads to completely new functionalities of this mainstream semiconductor in numerous fields ranging from nanofluidics and biosensorics to drug delivery, energy storage and photonics. However, a difficult to assess elasticity significantly limited its mechanical exploration and application so far. The ultimate goal of this project is to expand nanoporous silicon’s applications further to the phononic field and to develop a novel hybrid nano-material system with thermally and electrically tunable elastic properties, scalable to industrial needs. The key to achieve this is the combination of wafer-scale nanoporous silicon with liquid crystal elastomers confined in its pores. In order to comprehensively characterize and understand the hybrid’s elastic behavior, we propose to utilize the unparalleled insights provided by in-situ laser ultrasonics and sophisticated computational methods.The assessment of the acoustics will enable the observation of numerous effects: the influence of the pore morphology and porosity gradient orientation on wave propagation, the compressibility of liquid-like, viscoelastic materials in confined spaces and the hybrid’s tuneable elasticity. With complementary advanced X-ray diffraction investigations, we will explore the structure of the liquid crystal elastomers, the role of the confinement and the phase behavior on different stimuli. Ultimately, these insights will allow us to fine tune the material design and synthesis to achieve specific temperature and electric stimulus-dependent elastic properties with potential applications in the field of micro-electro-mechanical systems and in the emerging field of phononics.