3D characterization of coated nanoparticles and soft-hard nanocomposites
5 September 2018
Campus Groenenborger, U0.24 - Groenenborgerlaan 171 - 2020 Antwerpen (route: UAntwerpen, Campus Groenenborger
Organization / co-organization:
Department of Physics
PhD defence Nathalie Claes - Faculty of Science, Department of Physics
The implementation of nanomaterials into commercial products such as paints, catalysts and pharmaceuticals is often hampered by a poor flowability, the occurrence of oxidation or limited dispersion properties. Therefore, many efforts have been made to improve these functional properties by the development of surface engineering techniques such as wet chemical methods, plasma treatment and atomic layer deposition. The surface of the nanomaterial can be modified by applying a coating, enabling one to tune and improve the properties of the nanocompounds. Often, a “soft” coating is applied to a “hard” nanoparticle, which complicates the characterization of these soft-hard hybrid materials. It is therefore only by finding solutions to overcome problems related to the characterization of these nanomaterials and their coating, that we can understand and optimize the properties of coated nanomaterials.
The main purpose of this thesis is to provide novel approaches that enable the investigation of coated nanoparticles and soft-hard nanocomposite materials. Such studies, including the 3D characterization of the presence and uniformity of a coating or the penetration depth of a coating in porous materials, enables one to improve different surface engineering techniques and process parameters. Moreover, the information following from such studies can be used to interpret optical signals and may serve as an input for theoretical calculations. The 2D and 3D characterization in this thesis was performed by transmission electron microscopy (TEM). Advanced sample preparation methods together with different imaging and spectroscopic techniques were evaluated and combined in the most optimal approaches to reach the goals in this thesis.
On the basis of the results of different studies of coated nanoparticles and soft-hard nanocomposites, it can be concluded that the optimization of the supporting TEM grid and the use of advanced imaging methods, such as exit wave reconstruction, have enabled the simultaneous visualization and characterization of coated nanoparticles. In addition, methods which are often used in life sciences, such as cryo-electron tomography, have been successfully applied to soft-hard composites in order to investigate material science related questions. In conclusion, the characterization provided the necessary information to link the structure to the properties of the coated nanomaterials and soft-hard nanocomposites.