Multifunctional antifreeze e-skin with self-healing and recyclability via cellulose nanocrystals-assisted poly(thioctic acid)-iron coordination networks.

Human skin exhibits remarkable self-healing and responsiveness, attributed to dynamic disulfide (SS) bonds. However, traditional elastomer polymers often suffer from poor mechanical performance, low stability, and weak signal-capture capabilities due to metastability and insufficient interchain interactions. To overcome these limitations, a novel strategy combining inverse vulcanization and iron(III)-carboxylate coordination was proposed to construct a multifunctional, recyclable elastomer named PTCFe. In this system, thioctic acid (TA) undergoes inverse vulcanization with maleic acid-modified cellulose nanocrystals (MACNC), forming a robust dynamic network. Subsequently, ferric chloride (FeCl₃) induces multivalent Fe3+-carboxylate coordination, further reinforcing the polymer matrix. The presence of abundant hydrogen bonds and dynamic SS linkages synergistically enhance interchain interactions. As a result, PTCFe demonstrates high optical transparency (>90 %), exceptional stretchability (up to 1200 %), and strong adhesion (1368.56-1938.76 KPa) to diverse surfaces. It also exhibits outstanding self-healing efficiency (up to 89.6 %) and skin-friendly properties, maintaining stable signal detection during strenuous activities such as mountaineering, even under subzero conditions. Moreover, the elastomer is fully recyclable by thermal remelting and shows rapid biodegradability in soil. The PTCFe with above properties as a promising platform for next-generation wearable sensors and electronic skin (e-skin).