Cross-Links–Entanglements Integrated Networks Contributing to Highly Resilient, Soft, and Self-Adhesive Elastomers with Low Hysteresis for Green Wearable Electronics

Abstract

Green wearable electronics are attracting increasing attention to eliminate harmful byproducts generated by traditional devices. Although various degradable materials have been explored for green wearable electronics, the development of degradable elastomers with integrated characteristics of low modulus, self-adhesion, high resilient, and low hysteresis remains challenging. In this work, a degradable elastomer poly­(1,8-octanediol-co-citrate-co-caprolactone) (POCL) is reported, in which a loosely cross-linked network contains plenty of entangled flexible chains. The coexistence of covalent cross-links and entanglements of long polymer chains endows the elastomer with good resilience and low hysteresis, in addition to low modulus and self-adhesion. Taking advantage of the unique mechanical properties, epidermal strain sensors based on the POCL elastomer were prepared, which exhibited good adhesion to human skin, high sensitivity, high response rate, and excellent fatigue resistance. We also fabricated stretchable electroluminescent devices using this degradable elastomer and demonstrated the recyclability of the nondegradable materials in the electronic device.

Recent development of biodegradable synthetic rubbers and bio-based rubbers using sustainable materials from biological sources

“…7 Mechanical strength reinforcement by fibrous fillers through physical entanglement. 117 TS, tear strength, and hardness increased with increasing ller content, whereas EB increased only slightly at a certain ller concentration before decreasing at higher ller loading. The inverse reinforcement between TS and EB was also seen in most conventional synthetic rubber llers such as carbon black, silica, and clay materials.…”

Scalable and Degradable Dextrin-Based Elastomers for Wearable Touch Sensing

“…In this system, however, the manipulation became challenging and fatigue life got limited because of the POMAC’s sticky gel nature. By using poly­(1,8-octanediol- co -citrate- co -caprolactone), the sticky gel aspect was improved, but the gel contents showed that the majority of PCL is not in the crosslinked network, which may impart stability issues.…”

Hybrid Nanoarchitectonics with Conductive Polymer-Coated Regenerated Cellulose Fibers for Green Electronics

“…Recently, electronic waste (e-waste) has emerged as a serious contamination problem in the environment. − This is because of the rapid development in electronics technology, short lifetime of electronic devices, and high recycling cost. − Furthermore, discarded e-waste may lead to the release of large toxic elements, including heavy metals and hazardous chemicals, which could eventually enter the biological system via soil, water, and human food chains. , To address this problem of e-waste, a promising strategy is to develop “green” electronic devices based on biodegradable or renewable polymers. Interestingly, green flexible electronic devices, which comprise biodegradable celluloses, have garnered considerable attention for a variety of applications since cellulose is an abundant, low-cost, and sustainable material. − Many laboratories, including ours, have been dedicated to the development of various conductive composites based on cellulose for green electronics, to retain conductivity and introduce environmental friendliness and facile recycling/disposal. − …”

“…7−9 Furthermore, discarded e-waste may lead to the release of large toxic elements, including heavy metals and hazardous chemicals, which could eventually enter the biological system via soil, water, and human food chains. 10,11 To address this problem of e-waste, a promising strategy is to develop "green" electronic devices based on biodegradable or renewable polymers. Interestingly, green flexible electronic devices, which comprise biodegradable celluloses, have garnered considerable attention for a variety of applications since cellulose is an abundant, low-cost, and sustainable material.…”