Preparation of Waterborne Polyurethane/ Silsesquioxane /Carbon Nanotubes Aerogel with Rigid-Flexible Framework for Mechanically Tough and Wide Pressure-Range Properties for High-Performance Piezoresistive Sensing

Abstract

The piezoresistive response of flexible piezoresistive sensors is usually limited to narrow low-pressure regions, with limited linear stability during wide pressure variations, which presents a significant difficulty. In order to overcome this constraint, waterborne polyurethane (WPU) and hydroxylated silsesquioxane (HSQ) are covalently bonded to form a "rigid-flexible" hybrid framework. The typical problems of low mechanical strength, poor filler dispersion, and weak interfacial bonding in traditional aerogel sensors are all concurrently resolved by this molecular-level design. The resulting WPU-HSQ8/CNTs composite aerogel, created using an eco-friendly freeze-drying procedure, achieves a remarkable combination of mechanical toughness and electrical sensitivity by integrating multi-walled carbon nanotubes (MWCNTs) to form a continuous conductive network. The WPU-HSQ8/CNTs exhibits excellent dynamic stability under high compression rates, superior fatigue resistance over extended cycling, and stable multi-level piezoresistive response across an ultra-wide pressure range of 0–5 MPa—a capability rarely reached in prior studies. Its practical viability is proved by real-time tracking of human joint movements. The material offers a viable platform for next-generation flexible sensors in wearable health monitoring, electronic skin, and human-machine interface by presenting a material design strategy that resolves the long-standing trade-off between operational range and sensing stability.