Dynamic Response Crosslinking Units Endow Polyurethane Elastomers with Synergistic Mechanical robustness, Multiphase pH Sensing Capability, and Recyclability for Sustainable Environmental Monitoring

Abstract

Polyurethane (PU) elastomers suffer from a long-standing critical trade-off between mechanical reinforcement and functionalization, severely limiting their applications. To address this, this study proposes an innovative design paradigm based on Dynamic Responsive Crosslinking Units (DRCU)-achieving precise control over material properties by 2 integrating structural connectivity, responsiveness, and dynamic reversible mechanisms. By incorporating tetra(p-hydroxyphenyl)ethylene (TPE-TOH) into the PU matrix, a supramolecular elastomer (TTPU-3) with exceptional performance was fabricated: true fracture stress 69.9 MPa, toughness 367.7 MJ m -3 , elongation at break up to 1873%, 97% optical transmittance, and excellent recyclability (retaining 94% mechanical properties after 3 cycles) via dynamic hydrogen bonds. DRCU sites' reversible protonation/deprotonation enables solventtriggered activation of TTPU-3, producing fast, reversible color changes across pH 1-14. An RGB-pH model realizes quantitative color-pH correlation for non-destructive, accurate multiphase pH detection. TTPU-3 was also developed into a controllably activated multimodal anticounterfeiting label. This paradigm overcomes PU's mechanicalfunctionalization bottleneck, endows sustainability, and offers a promising pathway for advanced environmental monitoring and high-safety applications.