Degradable and Fully Recyclable Dynamic Thermoset Elastomer for 3D‐Printed Wearable Electronics

Abstract

Wearable electronics have become an important part of daily lives. However, its rapid development results in the problem of electronic waste (e‐waste). Consequently, recyclable materials suitable for wearable electronics are highly sought after. In this study, a conductive recyclable composite (PFBC) is designed based on a dynamic covalently cross‐linked elastomer and hierarchical hybrid nanofillers. The PFBC shows excellent wide‐ranging properties including processability, elasticity, conductivity, and stability, which are superior to previous materials used for recyclable electronics, and exhibits outstanding mechanical properties and environmental tolerance including high temperature, high humidity, brine, and ethanol owing to its covalent cross‐linking. Reversible dissociation of Diels–Alder networks allows for convenient processing and recycling. After three recycles, the toughness of the PFBC remained at 10.1 MJ m−3, which is conspicuous among the reported recyclable electronic materials. Three types of PFBC‐based wearable electronics including a triboelectric nanogenerator, a capacitive pressure sensor, and a flexible keyboard, are successfully 3D printed with excellent performance. The PFBC possessed both recyclability and degradability, the combination of which provides a new way to reduce e‐waste. This is the first work to recycle electronics using direct 3D printing and presents promising new design principles and materials for wearable electronics.

A Review on Printed Electronics: Fabrication Methods, Inks, Substrates, Applications and Environmental Impacts

“…Recent developments on organic inks and lignocellulosic substrates have demonstrated the printability of biocompatible and/or recyclable sensing devices. To name a few, Kim et al [51] fabricated entirely 3D-printed disposable ion sensor, Ling et al [52] explored the feasibility of inkjet-printed PEDOT:PSS/nanopaper-based touch sensor and Guo et al [53] demonstrated a 3D-printed pressure sensor composed of degradable and fully recyclable thermoset elastomers. These sensors attest to their potential applications in wearable and transient electronics.…”

Self-Assembly 3D Porous Crumpled MXene Spheres as Efficient Gas and Pressure Sensing Material for Transient All-MXene Sensors

“…Recently, transient gas and pressure sensors have been emerging [ 7 , 8 ]. Jiang et al developed a transient paper-based composite decorated with reduced graphene oxide and polyaniline with ammonia sensitivity and partial degradation [ 9 ].…”

Solving the difficult recyclability of conventional thermosetting polyurea elastomers based on commercial raw materials in a facile way

“…However, these TPUEs maintained a rubbery plateau above T g of the hard segment due to the crosslinking network structure. 21 The TGA results showed that the initial decomposition temperatures of all TPUEs were >260 C and the highest decomposition temperature was recorded in the range from 300 to 400 C due to the thermal decomposition of urea bonds, indicating their outstanding thermal stability (Fig. S3 †).…”