Sustainable Reactive Polymer Coating Platform for Durable Wearable Colorimetric pH-Sensing Textiles with Tunable Acid–Base Responsiveness

Abstract Wearable colorimetric pH-sensing textiles provide a power-free, noninvasive platform for healthcare and environmental monitoring, yet their sustainable deployment was hindered by short service life, dye leaching-induced aquatic pollution, and substrate-dependent manufacturing with redundant process development. Herein, a universal two-step reactive polymer coating strategy is developed to fabricate robust pH-sensing textiles independent of inherent fiber chemistry, with catalyst-free ambient fabrication and covalent dye immobilization as core sustainable advances. An amine-rich cross-linked interlayer was first formed in situ on textile surfaces via aza-Michael addition between dipentaerythritol pentaacrylate (5Acl) and branched polyethylenimine (BPEI), offering abundant covalent anchoring sites and a tunable microenvironment to modulate the chromophore acid–base response. Acrylate-functionalized nitrazine yellow (GMA-NY) was then covalently grafted through a secondary Michael addition, imparting reversible pH-sensing capability. The sensor exhibits reversible yellow–green–blue trichromatic transitions over pH 1.0–8.0, only a 6% color strength loss after 10 washing cycles, and a tailored apparent pKa (3.13 ± 0.65) for early bacterial infection warning. Compatible with diverse fibers and extendable to rewritable information recording and vapor detection, this substrate-agnostic platform establishes a scalable, sustainable design paradigm for wearable sensors.