Effect of Silane Functionalization on the Properties of Polydimethylsiloxane Nanocomposites Reinforced with Reduced Graphene Oxide and Carbon Nanotubes

Elastomeric nanocomposites containing carbon nanomaterials have potential for functional applications, although their performance depends on filler–matrix interactions and conductive network formation. This study evaluated the effects of KH550 functionalization and rGO or SWCNT concentration on the thermal, mechanical, and electrical properties of PDMS nanocomposites. Nanomaterial modification was characterized by Raman spectroscopy, SEM, and XPS, while nanocomposites were evaluated by AC conductivity, thermogravimetric analysis, and tensile testing. XPS evidenced changes in surface chemical composition following functionalization. Incorporating up to 2.0 wt.% rGO did not appreciably alter PDMS conductivity, whereas 0.1 wt.% SWCNT increased conductivity from 2.8 × 10−14 to 2.7 × 10−6 S/m at 0.1 Hz, approximately eight orders of magnitude. SWCNT functionalization reduced conductivity, although increasing filler concentration partially compensated for this effect. At 0.5 wt.% SWCNT, functionalization resulted in 129% higher mean tensile strength and 52% higher mean elongation at break compared with the unfunctionalized nanocomposite. Both nanomaterials modified the thermal behavior of PDMS, while mechanical effects depended on filler type, concentration, and functionalization. These results highlight the need to balance filler–matrix interactions and conductive network formation in PDMS nanocomposites.