Different polysiloxane networks obtained via a cross-linking process have served as matrices for the incorporation of metallic Pt particles by chemical reduction of metal ions from PtCl₄ in THF solution in the presence of active Si–H groups remaining in the networks. Polysiloxane networks have been prepared by hydrosilylation of D₄/V₄ polysiloxane with branched (Q(M^H)₄) or cyclic (D^H ₄) hydrosiloxanes, at different molar ratios of reagents. The influence of various topologies of matrices on the amount of introduced metal particles and their distribution in the matrix was investigated. Network–Pt systems, thus formed, have been characterized using FTIR spectroscopy, swelling measurements, X-ray diffraction, SEM and TEM microscopy combined with EDX microanalysis, and thermogravimetric studies. The reduction of platinum ions was monitored using UV-vis spectroscopy. The consumption of Si–H groups, accompanying the reduction, was investigated by IR measurements. Depending on the applied matrix, different amounts of platinum were introduced. XRD studies have confirmed the incorporation of Pt(0) into all obtained systems. It was established that the systems contained metal nanoparticles (size 3–6 nm). Microscopic investigations have shown that the size and the arrangement of Pt crystallites formed depend on the type of matrix applied. Catalytic performance of examined systems investigated using isopropyl alcohol conversion as the test reaction indicated mainly redox type activity. It was found that Pt dispersed in Q–P type supports, i.e. the polysiloxane networks obtained using the branched hydrosiloxane as the cross-linking agent, showed higher catalytic activity than Pt dispersed in C–P type matrices – the networks obtained with the application of the cyclic hydrosiloxane. The comparison of the behavior of synthesized samples with standard Pt/alumina catalyst in isopropyl alcohol conversion revealed higher redox activity of polysiloxane-supported systems in the lower temperature range.

Polysiloxanes with silver nanoparticles (Ag NPs) have garnered attention for their distinctive physicochemical properties, which make them promising candidates for advanced material applications. This study presents a systematic investigation into the thermal properties and degradation mechanisms of polysiloxane/Ag nanocomposites, emphasising the innovative incorporation of Ag NPs directly into polysiloxane networks via in situ reduction of Ag⁺ ions by Si-H groups. Six polysiloxane matrices were synthesised by hydrosilylation of poly(methylhydrosiloxane) (PMHS) or poly(vinylsiloxane) (polymer V₃) with three cross-linking agents of varying molecular structures and functionality. Thermogravimetric analysis combined with mass spectrometry revealed that the introduction of Ag NPs alters the thermal properties of polysiloxane networks, primarily affecting the redistribution of Si bonds that occurs during the pyrolysis of these systems. Monitoring the pyrolysis process using FTIR spectroscopy allowed us to investigate the effect of the presence of Ag NPs on the degradation mechanism of the studied nanocomposites. The presence of the free-carbon phase and metallic silver phase in the Ag-containing silicon oxycarbide materials obtained was confirmed by Raman spectroscopy and XRD analyses, respectively. These findings demonstrate the possibility of fabricating Ag/SiOC materials with ceramic residues in the range of 43 to 84%. This work provides new insights into the thermal behaviour of polysiloxane/Ag nanocomposites and underscores their potential for high-performance applications in thermally demanding environments.