Streltsov Dmitry R, Borisov Kirill M, Kalinina Aleksandra A, Muzafarov Aziz M
Enikolopov Institute of Synthetic Polymeric Materials of Russian Academy of Sciences, 117393 Moscow, Russia.
A.N. Nesmeyanov Institute of Organoelement Compounds of Russian Academy of Sciences, 119334 Moscow, Russia.
Nanomaterials (Basel). 2023 Jun 23;13(13):1916. doi: 10.3390/nano13131916.
Silica hollow spheres with a diameter of 100-300 nm and a shell thickness of 8±2 nm were synthesized using a self-templating amphiphilic polymeric precursor, i.e., poly(ethylene glycol)-substituted hyperbranched polyethoxysiloxane. Their elastic properties were addressed with a high-frequency AFM indentation method based on the PeakForce QNM (quantitative nanomechanical mapping) mode enabling simultaneous visualization of the surface morphology and high-resolution mapping of the mechanical properties. The factors affecting the accuracy of the mechanical measurements such as a local slope of the particle surface, deformation of the silica hollow particles by a solid substrate, shell thickness variation, and applied force range were analysed. The Young's modulus of the shell material was evaluated as E=26±7 GPa independent of the applied force in the elastic regime of deformations. Beyond the elastic regime, the buckling instability was observed revealing a non-linear force-deformation response with a hysteresis between the loading and unloading force-distance curves and irreversible deformation of the shell at high applied forces. Thus, it was demonstrated that PeakForce QNM mode can be used for quantitative measurements of the elastic properties of submicon-sized silica hollow particles with nano-size shell thickness, as well as for estimation of the buckling behaviour beyond the elastic regime of shell deformations.
使用自模板两亲性聚合物前体，即聚（乙二醇）取代的超支化聚乙氧基硅氧烷，合成了直径为100 - 300 nm且壳厚度为8±2 nm的二氧化硅空心球。基于PeakForce QNM（定量纳米力学映射）模式的高频原子力显微镜压痕方法研究了它们的弹性特性，该模式能够同时可视化表面形态并对机械性能进行高分辨率映射。分析了影响机械测量准确性的因素，如颗粒表面的局部斜率、固体基底对二氧化硅空心颗粒的变形、壳厚度变化以及施加力范围。在弹性变形范围内，壳材料的杨氏模量评估为E = 26±7 GPa，与施加力无关。在弹性范围之外，观察到屈曲不稳定性，揭示了加载和卸载力 - 距离曲线之间具有滞后的非线性力 - 变形响应以及在高施加力下壳的不可逆变形。因此，证明了PeakForce QNM模式可用于定量测量具有纳米级壳厚度的亚微米级二氧化硅空心颗粒的弹性特性，以及估计壳变形弹性范围之外的屈曲行为。
