Interface-Engineered Thermoplastic Polyurethane/Ethylene-Propylene-Diene Monomer Composite Foams for Durable Silicon Carbide Polishing Pads

Chemical mechanical polishing (CMP) of silicon carbide (SiC) operates under simultaneous mechanical loading and strong oxidative environments, placing stringent demands on polishing pad materials. High-hardness thermoplastic polyurethane (TPU), although widely employed, exhibits insufficient compliance, localized stress accumulation, and vulnerability to fatigue damage during prolonged operation. Meanwhile, the tribological response of polymer composites under such coupled mechanical-oxidative conditions remains insufficiently understood. Here, ethylene-propylene-diene monomer (EPDM) was introduced to modify high-hardness TPU, while interfacial compatibility and structural robustness were tailored using maleic anhydride grafted EPDM (EPDM-g-MAH) and irradiation-induced network formation. Microcellular foams with similar expansion ratios and cell sizes were prepared using supercritical carbon dioxide (CO 2 ) foaming, enabling a systematic assessment of their wear and tribological performance. The modified systems exhibit improved wear resistance, as evidenced by reduced material loss and suppressed damage evolution compared to neat TPU. Notably, the introduction of microcellular architecture leads to an environment-dependent trade-off effect: while the reduced load-bearing capacity deteriorates wear resistance under nonoxidative conditions, the cellular structure enhances durability in oxidative environments by restricting the penetration of reactive species. The tribological response is governed by the combined influence of phase organization, interfacial cohesion, and network constraints, which together contribute to more stable sliding behavior. Improved resistance to thermal perturbation further contributes to maintaining functional integrity during sliding. These findings clarify the interplay between interfacial design and structural architecture, providing an interface-controlled design strategy for developing advanced polymer-based composite polishing materials for SiC CMP applications.