Room Temperature Solid State Synthesis, Characterization, and Application of a Zinc Complex with Pyromellitic Acid

Stretchable, Environment-Stable, and Knittable Ionic Conducting Fibers Based on Metallogels for Wearable Wide-Range and Durable Strain Sensors

The construction of fibrous ionic conductors and sensors with large stretchability, low-temperature tolerance, and environmental stability is highly desired for practical wearable devices yet is challenging. Herein, metallogels (MOGs) with a rapidly reversible force-stimulated sol-gel transition were employed and encapsulated into a hollow thermoplastic elastomer (TPE) microfiber through a simple coaxial spinning. The resultant MOG@TPE coaxial fiber exhibited a high stretchability (>100%) in a broad temperature range (-50 to 50 °C). The MOG@TPE fibrous strain sensor demonstrated a high-yet-linear working curve, fast response time (<100 ms), highly stable conductivity under large deformation, and excellent cycling stability (>3000 cycles). The MOG@TPE fibrous sensors were demonstrated to be directly attached to the human skin to monitor the real-time movements of large/facet joints of the elbow, wrist, finger, and knee. It is believed that the present work for preparing the stretchable ionic conductive fibers holds great promise for applications in fibrous wearable sensors with broad temperature range, large stretchability, stable conductivity, and high wearing comfort.

Incorporation of tetracarboxylate ions into octacalcium phosphate for the development of next-generation biofriendly materials

Octacalcium phosphate (OCP; Ca₈(HPO₄)₂(PO₄)₄ ∙ 5H₂O) is a precursor of hydroxyapatite found in human bones and teeth, and is among the inorganic substances critical for hard tissue formation and regeneration in the human body. OCP has a layered structure and can incorporate carboxylate ions into its interlayers. However, studies involving the incorporation of tetracarboxylic and multivalent (pentavalent and above) carboxylic acids into OCP have not yet been reported. In this study, we investigate the incorporation of pyromellitic acid (1,2,4,5-benzenetetracarboxylic acid), a type of tetracarboxylic acid, into OCP. We established that pyromellitate ions could be incorporated into OCP by a wet chemical method using an acetate buffer solution containing pyromellitic acid. The derived OCP showed a brilliant blue emission under UV light owing to the incorporated pyromellitate ions. Incorporation of a carboxylic acid into OCP imparted new functions, which could enable the development of novel functional materials for biomedical applications.