Intrinsic Effect of Nanoparticles on the Mechanical Rupture of Doubled-Shell Colloidal Capsule via In Situ TEM Mechanical Testing and STEM Interfacial Analysis

The discovery of Pickering emulsion templated assembly enables the design of a hybrid colloidal capsule with engineered properties. However, the underlying mechanisms by which nanoparticles affect the mechanical properties of the shell are poorly understood. Herein, in situ mechanical compression on the transmission electron microscope and aberration-corrected scanning transmission microscope are unprecedentedly implemented to study the intrinsic effect of nanoparticles on the mechanical properties of the calcium carbonate (CaCO₃ )-decorated silica (SiO₂ ) colloidal capsule. The stiff and brittle nature of the colloidal capsule is due to the interfacial chemical bonding between the CaCO₃ nanoparticles and SiO₂ inner shell. Such bonding strengthens the mechanical strength of the SiO₂ shell (166 ± 14 nm) from the colloidal capsule compared to the thicker single SiO₂ shell (310 ± 70 nm) from the silica hollow sphere. At elevated temperature, this interfacial bonding accelerates the formation of the single calcium silicate shell, causing shell morphology transformation and yielding significantly enhanced mechanical strength by 30.9% and ductility by 94.7%. The superior thermal durability of the heat-treated colloidal capsule holds great potential for the fabrication of the functional additives that can be applied in the wide range of applications at elevated temperatures.

Visualization of materials using the confocal laser scanning microscopy technique

The development of materials science always benefits from advanced characterizations. Currently, imaging techniques are of great technological importance in both fundamental and applied research on materials. In comparison to conventional visualization methods, confocal laser scanning microscopy (CLSM) is non-invasive, with macroscale and high-contrast scanning, a simple and fast sample preparation procedure as well as easy operation. In addition, CLSM allows rapid acquisition of longitudinal and cross-sectional images at any position in a material. Therefore, the CLSM-based visualization technique could provide direct and model-independent insight into material characterizations. This review summarizes the recent applications of CLSM in materials science. The current CLSM approaches for the visualization of surface structures, internal structures, spatial structures and reaction processes are discussed in detail. Finally, we provide our thoughts and predictions on the future development of CLSM in materials science. The purpose of this review is to guide researchers to build a suitable CLSM approach for material characterizations, and to open viable opportunities and inspirations for the development of new strategies aiming at the preparation of advanced materials. We hope that this review will be useful for a wide range of research communities of materials science, chemistry, and engineering.