Electrostatic Repulsion-Induced Highly Enhanced Dispersibility of Conductive Carbon Electrode with Shape Memory-Assisted Self-Healing Effect for Multi-Modal Sensing System

A composite with shape memory-assisted self-healing and piezoresistive sensing ability is presented herein, and its high conductivity is attributed to a small amount of well-dispersed carbon black (CB). Carboxylic acid groups are introduced into the polyvinyl butyral (PVB) side chain via the ring-opening reaction of succinic anhydride. Thus, CB is well-dispersed in the solution owing to simultaneous attraction and electrostatic repulsion. The resulting ink with less than 30 wt.% CB is highly conductive (3.7 S cm(-1)). In addition, hexamethylene diisocyanate (HDI) is used as a crosslinking agent to promote the reaction between -OH and -COOH in the side chains of the PVB-COOH. The dual network consisting of urethane and amide bonds exhibits the shape memory effect. Moreover, the composite is shown to be capable of shape memory-assisted self-healing owing to the hydrogen bonds between the dual network and -COOH, such that the resistance returns to its initial value, and the healed sample can support a 1 kg weight. The resulting multi-modal sensing system is shown to detect bio-signals such as body movements, breathing, and pulse. In summary, the present work provides an effective strategy for the development of conductive composite electrodes for various applications that require adaptability and piezoresistive sensing ability.

Automated summary

In this work, a composite material with shape memory-assisted self-healing and piezoresistive sensing ability is presented. The high conductivity of the material is attributed to a small amount of well-dispersed carbon black. Carboxylic acid groups are introduced into the polyvinyl butyral (PVB) side chain via a ring-opening reaction. The resulting ink with less than 30 wt.% carbon black exhibits high conductivity (3.7 S cm(-1)). Hexamethylene diisocyanate (HDI) is used as a crosslinking agent to promote the reaction between -OH and -COOH in the PVB-COOH side chains, resulting in a dual network with urethane and amide bonds that exhibits shape memory effect. The composite material is also capable of shape memory-assisted self-healing due to the hydrogen bonds between the dual network and -COOH, and it can detect bio-signals such as body movements, breathing, and pulse.