Antiswellable, Conductive, and Recyclable Coacervate Polyacrylamide/Tannic Acid Composite Hydrogel for Underwater Wearable Sensors

Abstract

Hydrogel-based sensors have attracted increasing attention as fascinating materials for various applications in biomedicine and bioelectronics. However, the application of strain sensors underwater remains a great challenge due to the swelling of hydrogels in an aqueous environment. Herein, we report a coacervate conductive polyacrylamide/tannic acid (PAM/TA) composite hydrogel with strong antiswellable properties. The PAM/TA composite hydrogel exhibits a good electrical performance, where the conductivity is found to be 2.7 × 10 −4 S/cm, which is stable during recycling, with an excellent stretchability of 1000% at a tensile strength of 1.5 MPa. The composite hydrogel shows excellent biocompatibility and antiswellable behavior and maintains long-term stability underwater to monitor human movements. In addition, the environmentally friendly composite hydrogel can be recycled repeatedly. The PAM/TA composite hydrogel with excellent antiswelling and stability, good electrical performance, and remarkable stretchability has great potential for the applications as underwater wearable sensors.

Underwater Fabrication of Carbon Nanotube/Coacervate Composites

“…Previous hybrid systems have been made by coacervating metal oxide ((Pb,Bi)­(Ti,Fe)­O 3 or CeO 2 ) micro- or nanoparticles with polyelectrolytes − through intermolecular interactions, or by directly forming coacervates, using negatively charged nanoparticles, e.g., quantum dots, as the polyanion. , The organic–organic composites have been constructed by loading a coacervate matrix with active organic materials such as curcumin, baicalin, plasmid DNA, bortezomib anticancer drug, or liposomes. − These hybrid materials show diverse physical and chemical characteristics including piezoelectric, fluorescent, , film-formation, antibiofouling, and redox properties. Some of these materials have been used as pharmaceutical carriers. , While a hybrid system with electrical conductivity is known through the recent work of Tang and coauthors on conductive polyacrylamide/tannic acid composite coacervate and Mu and coauthors on silver-filled coacervate which opens up for vast application opportunities within electronics.…”