Structure of metal-plasma polymer Ag/HMDSO nanoparticles and its thermal development studied by X-ray scattering methods

Tereza Košutová¹, Lukáš Horák¹, Artem Shelemin², Mykhailo Vaidulych², Jan Hanuš², Hynek Biederman², Ondřej Kylián², Pavel Solař², Miroslav Cieslar³, Andrei Choukourov², Milan Dopita¹

¹Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague 2, Czech Republic

²Department of Macromolecular Physics, Faculty of Mathematics and Physics, Charles University, V Holešovičkách 2, 180 00 Prague 8, Czech Republic

³Department of Physics of Materials, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, 121 16 Prague 2, Czech Republic

KosutovaT@gmail.com

Nowadays, nanomaterials are certainly a very hot topic in society. The efforts to prepare heterogeneous nanoparticles, i. e. nanoparticles composed of parts from different materials, are driven by their interesting characteristics coming from the combination and synergy of individual materials properties.

This study follows up heterogeneous nanoparticles composed of a silver core and polymeric shell. These so-called core@shell nanoparticles were prepared by a combination of magnetron-based gas aggregation cluster source (GAS) and simultaneous plasma enhanced chemical vapour deposition of hexamethyldisiloxane (HMDSO). A series of Ag nanoparticles prepared at various HMDSO pressure was prepared.

Studied samples differ in the size of the silver core and also in the thickness of the polymeric shell. These properties can be tuned by the amount of HMDSO supplied to the deposition chamber. During the process without HMDSO nanoparticles of size around 40 nm are created on the other hand with 9 % of HMDSO supplied near to the target surface, the diameter of nanoparticles decreases to 5 nm. Size of coherently diffracting domains does not depend on the amount of added HMDSO and stays around 5 nm. Microstrain and density of stacking faults increases with the concentration of HMDSO in the system, the details were published in [1].

Thermal properties of heterogeneous metal-polymer nanoparticles were investigated by methods of small angle x-ray scattering, x-ray diffraction, ultraviolet-visible spectroscopy and electron microscopy. The changes in size distribution, shape, and microstructure of nanoparticles with increasing temperature up to 450 °C were observed and determined.

XRD patterns of selected samples before and after heating to 450 °C were analysed. With increasing temperature, the ordering of atoms is observed, the decrease in density of stacking faults and relaxation of lattice parameters. Thermal evolution of size for pure silver nanoparticles and the silver cores of nanoparticles prepared with the lowest amount of HMDSO added to the aggregation chamber is depicted in figure 1. The comparison with pure silver nanoparticles shows that the polymeric shell around nanoparticles prevents nanoparticles fusion. The growth of heterogeneous nanoparticles takes place above 350 °C, coalescence temperature for pure silver nanoparticles is below 100 °C.

Figure 1. Temperature dependence of nanoparticles silver core diameter for pure silver nanoparticles and nanoparticles prepared with the lowest amount of HMDSO in the aggregation chamber.

1. T. Košutová et al., “Synthesis and microstructure investigation of heterogeneous metal-plasma polymer Ag/HMDSO nanoparticles,” Surf. Interface Anal., no. 2019, pp. 1–4, 2020, doi: 10.1002/sia.6779.

The authors acknowledge the financial support from the project NanoCent—Nanomaterials Centre for Advanced Applications, Project No. CZ.02.1.01/0.0/0.0/15_003/0000485, financed by ERDF.