Low-Loading Silane-Modified SiO2-Reinforced MOCA-Based Cast Polyurethane Elastomers: Enhanced Wear Resistance and Mechanical Performance

4,4′-Diaminodiphenylmethane (MOCA)-based cast polyurethane (CPU) elastomers possess excellent mechanical properties but often exhibit insufficient wear resistance under high-load or abrasive conditions. To address this, surface-modified silica nanoparticles (D-SiO 2 ) were prepared using (N, N-dimethyl-3-aminopropyl)trimethoxysilane (DAPS) and incorporated into the CPU matrix via a solvent-assisted casting method. The introduced tertiary amine and organic groups on D-SiO 2 facilitated covalent bonding and hydrogen bonding with the CPU, significantly enhancing interfacial compatibility and dispersion uniformity. At an optimal loading of 0.3 wt%, the composite achieved a remarkable tensile strength of 59.1 MPa and an elongation at break of 394.75%, representing a substantial improvement over the neat CPU (44.2 MPa, 376.33%). Furthermore, the wear resistance was notably enhanced, with the abrasion volume reduced by 34% compared to the unfilled system, while the friction coefficient remained stable. This work demonstrates that low-loading, surface-modified silica can effectively reinforce MOCA-based CPUs, offering a viable strategy for developing high-performance MOCA-based CPU elastomers.