Mechanically Tough and Highly Stretchable Hydrogels Based on Polyurethane for Sensitive Strain Sensor.

Area of Science:

• Materials Science
• Polymer Chemistry
• Nanotechnology
• Wearable Sensors

Background:

• Hydrogels are promising for wearable sensors due to their flexibility and stretchability.
• Traditional hydrogels exhibit limitations such as brittleness and low electrical sensitivity, hindering their practical application.
• There is a need for enhanced hydrogel materials that overcome these limitations for robust sensor performance.

Purpose of the Study:

• To design and synthesize a novel hydrogel system with improved mechanical and electrochemical properties.
• To address the brittleness and low sensitivity issues in conventional hydrogel-based wearable sensors.
• To create a mechanically robust, highly stretchable, and sensitive dual-mode sensor using MXene nanosheets.

Main Methods:

• Synthesis of a macromolecular polyurethane crosslinking agent (PCA).
• Incorporation of PCA and two-dimensional (2D) MXene nanosheets into a covalently crosslinked hydrogel network.
• Characterization of the hydrogel's mechanical properties (tensile strength, elongation at break) and electrochemical performance.

Main Results:

• The PCA significantly enhanced the hydrogel's tensile strength (1.21 MPa) and stretchability (644% elongation at break).
• The inclusion of 2D MXene nanosheets imparted high electrical conductivity and strain sensitivity to the hydrogel.
• The optimized hydrogel demonstrated potential as a wearable device for continuous monitoring of human movements and facial microexpressions.

Conclusions:

• A novel hydrogel composite was successfully developed by combining PCA and MXene nanosheets.
• The developed material exhibits superior mechanical toughness, high stretchability, and excellent electrical sensitivity.
• This study presents an effective strategy for creating advanced MXene-based wearable sensors with dual-mode sensing capabilities.