A Dynamically Hybrid Crosslinked Elastomer for Room‐Temperature Recyclable Flexible Electronic Devices

Abstract

The rapid development of flexible electronics has resulted in serious pollution in the form of electronic waste. Accordingly, recyclability is highly desirable for these devices, but this remains a significant challenge. A dynamically hybrid crosslinked polyurethane (FPU) elastomer is designed in this study to address this challenge. Distinctive Diels-Alder adducts with suitable dissociation and reassociation dynamics are designed as crosslinking units to provide an efficient time frame for recycling. FPU is maintained in a state with a low crosslinking density after heating at 120 °C for 5 min. FPU-based electronics can therefore be dissolved in chloroform under ambient conditions to separate the electronic components and polymers for the refabrication of new electronic devices. This is the first reported thermoset elastomer that can be completely recycled at room temperature without chemical treatment to decompose the polymer chain. The design concept is applied by demonstrating the fabrication by recycling of different FPU-based flexible electronic devices: position sensor, flexible keyboard, and motion sensor. Furthermore, the FPU has many advantages as a material for flexible electronics in terms of its biomimetic mechanical properties, room-temperature self-healing, and facile processability. This study provides promising new design principles to develop materials for promoting sustainable flexible electronics.

Tough and Degradable Self-Healing Elastomer from Synergistic Soft–Hard Segments Design for Biomechano-Robust Artificial Skin

“…After multiple tensile tests and statistics, the PCL/PTHF-4AD 0.5 /2AD 0.5 film has been proved to have high toughness of 82.38 ± 2.40 MJ/m 3 , high fracture energy of 43299 ± 231 J/m 2 , and fast self-healing ability with 93 ± 2% efficiency, as shown in Figure S14. Figure i and Table S2 show that the degradability, toughness, and self-healing ability are better than previous reported self-healing elastomers. − ,,,,,− Therefore, the developed TDSE was a suitable elastomer to construct BA-skin for applications in humanoid robotics and prosthetic limbs.…”

Transient Chemical Activation of Covalent Bonds for Healing of Kinetically Stable and Multifunctional Organohydrogels

“…By contrast, the self-healing strategies based on reversible covalent bonds or supramolecular interactions are particularly suitable for improving the reliability of gels, not only because of their simple material fabrication procedures but also due to their effectiveness in dealing with multiple local healing events. 4,[13][14][15] Spontaneous intrinsic self-healing is widely preferred, [15][16][17][18] but the weaknesses of such strategy are first the dynamic chemistry-related poor kinetic stability/inertness that leads to noticeable shape change, creep, and unwanted fusion of pristine materials (Scheme 1a), 19,20 and second the dramatically decreased healing ability as residence time after damage increases. [21][22][23] Although external interventions such as light and heat can assist inactive solid films and coatings to generate a transient healing ability 13,24,25 and thus avoid the abovementioned problems, such intervention methods can not only accelerate the volatilization of the liquid in gels but can also have low efficiency in interior healing of large bulk gels.…”

Mechanically tough dry‐free ionic hydrogel microfibers swollen in aqueous electrolyte prepared by microfluidic devices

“…With the emerging research on soft electronic devices such as on‐skin electronics and wearable devices for human motion detection, stretchable conductive materials have attracted significant attention 2–24 . These next‐generation soft electronic materials are highly deformable and stretchable for wearable applications, beyond flexible and bendable.…”

“…Therefore, the development of mechanically strong soft materials with high conductivities is crucial. Recently, various types of deformable electronics have been fabricated with soft materials, mainly from polymeric systems such as hydrogels, 1–14 ionogels, 15–19 and elastomers 20–24 owing to their excellent mechanical and electrical properties. Among them, hydrogels consisting of hydrophilic polymer networks, have been considered as attractive based material for soft electronic system because they are stretchable, transparent, and able to be designed as conductive materials.…”