Abstract This study presents a novel single-component, moisture-curable sealant formulation based on silyl-terminated polyether (MS) polymer, reinforced with synergistic nanofillers including fumed silica and nano-calcium carbonate. The primary objective was to enhance the mechanical performance, thermal stability, and rheological behavior of the MS-based system through the strategic use of nanotechnology. Theoptimized formulation exhibited a tensile strength of 1.73 MPa and elongation-at-break of 175%, while shear strength increased to 1.97 MPa after seven days of curing under controlled temperature and humidity. Fourier transform infrared spectroscopy (FTIR) confirmed stronger intermolecular interactions and improved crosslinking density due to the presence of reactive nanoparticles. Thermogravimetric analysis (TGA) showed a noticeable enhancement in thermal resistance, particularly with fumed silica loading up to 0.9 wt%, which delayed thermal decomposition. Additionally, nano-calcium carbonate at 31.7 wt% contributed to better dimensional stability and homogeneous filler dispersion within the polymer matrix. The inclusion of 0.6 wt% fumed silica resulted in a 155% increase in adhesive strength compared to the unfilled formulation. Rheological analysis revealed superior thixotropy and sag resistance, making the sealant suitable for precision applications such as vertical joints or overhead installations. Overall, this work underscores the potential of nanofiller-enhanced MS polymers to meet demanding performance criteria, offering a scalable and robust solution for industrial sealing applications.

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