Self-Healing Ti₃C₂ MXene/PDMS Supramolecular Elastomers Based on Small Biomolecules Modification for Wearable Sensors

Abstract

Flexible conductive composites can be used as wearable strain sensors, which are widely used in the fields of new-generation robotics, electronic skin, and human detection. However, how to make conductive composites that simultaneously possess flexibility, stretchability, self-healing, and sensing capability is challenging research. In this work, we innovatively designed and prepared a silicone polymer conductive composite. MXenes and amino poly(dimethylsiloxane) were modified by small biomolecules via an esterification reaction and a Schiff base reaction, respectively. The modified MXenes are uniformly dispersed, which endows the composite with good electrical conductivity. The reversibility of multiple hydrogen bonds and imine bonds in the composite system makes it have ideal tensile properties and high-efficiency self-healing ability without external stimulation. The conductive composite containing 10 wt % A-MXenes showed an elongation of 81%, and its mechanical strength could reach 1.81 MPa. After repair, the tensile properties and the electrical conductivity could be restored to 98.4 and 97.6%, respectively. In addition, the conductive composite is further evaluated for the value of wearable strain sensors. Even after cut-healed processes, the conductive composite can still accurately detect tiny human movements (including speaking, swallowing, and pressing). This kind of self-healing MXene/PDMS elastomers based on the modification of small biomolecules has great potential as wearable strain sensors. This simple preparation method provides guidance for future multifunctional flexible electronic materials.

Flexible MXene‐Based Composites for Wearable Devices

“…The MXene-rubber elastomer sensor with a GF of 107.43, strain detection limit of 0.1%, and responding time of 50 ms could detect human motions after cut/healing process. Similarly, Zhang et al [36] prepared a self-healing MXene/PDMS supramolecular elastomer with excellent flexibility, stretchability, and conductivity. Here, MXene nanosheets and PDMS were modified by asparagine via an esterification reaction and a Schiff reaction, respectively.…”

“…Similarly, Zhang et al. [ 36 ] prepared a self‐healing MXene/PDMS supramolecular elastomer with excellent flexibility, stretchability, and conductivity. Here, MXene nanosheets and PDMS were modified by asparagine via an esterification reaction and a Schiff reaction, respectively.…”

MXene-Based Nanocomposite Sensors

“…Recently MXene/poly(dimethylsiloxane) strain sensors with a GF 3.6 have been successfully fabricated. 21 MXene/elastomer sensors with a GF 43–107 in the strain range of 0–10% were also reported. 9 On top of these, MXene-based sensors with a GF on the order of several thousands were discussed in the previous section; these are impressive achievements as other state-of-the-art sensors have a GF around 2.…”

“…This MXene/polymer nanocomposite sensor showed almost the same detection accuracy after being cut into two pieces and then were self-healed for 24 h. Both of the pristine and healed sensors were sensitive enough to detect and distinguish the movements of the throat of a human when he pronounced different words. 21 Guo et al 9 reported that a completely cut MXene/elastomer sensor self-healed and recovered about 100% of its initial tensile strength just after 90 min. It was also possible to twist, bend, and stretch the healed nanocomposite sensor without any problem.…”

Preparation Strategies and Applications of MXene‐Polymer Composites: A Review

“…The hydroxyl groups on the surface of MXene provide the possibility to introduce some functional groups via esterification reaction, such as amine groups [65][66][67] and long-chain alkanes. [68] It could increase the interactions between MXene and polymer and tune the surface chemistry of MXene.…”