Waterborne Polyurethane Enhanced, Adhesive, and Ionic Conductive Hydrogel for Multifunctional Sensors

Abstract

In the past two decades, ionic conductive hydrogel has attracted tremendous research interests for their intrinsic characteristics in the field of flexible sensor. However, synchronous achievement of high mechanical strength, satisfied ionic conductivity, and broad adhesion to various substrates is still a challenge. Herein, a novel zwitterionic composite hydrogel that displayed excited strechability (up to 900%), satisfied strength (about 30 kPa), high ionic conductivity (1.2 mS cm−1), and adhesion to polar and nonpolar materials is fabricated though the combination of waterborne polyurethanes (PU) and poly(sulfobetaine zwitterion‐co‐acrylamide) (SAm). Especially, this facile strategy demonstrates that PU has a synergistic effect on enhancing mechanical strength and ionic conductivity for ionic conductive hydrogel. Moreover, the hydrogel‐based strain/stress sensor shows high sensitivity, wide sensing range, great stability, and accuracy for human body movements detecting and voice recognition. This novel ionic conductive hydrogel has promoted the development of wearable devices.

Hydrogel adhesive formed via multiple chemical interactions: from persistent wet adhesion to rapid hemostasis

“…For example, although the PCT hydrogel easily forms hydrogen bonds and/or van der Waals forces with the surface of glass, PTFE, and PS, respectively, the smoothness of these surfaces is an obstacle to the adhesion strength. 23 On a relatively rough surface such as ceramic or stainless steel, its structure is conducive for the penetration of the polymer chains of the hydrogel into the surface pores to form mechanical interlocking and increased contact area, improving the adhesion. 24 Similarly, based on the relatively high roughness of the surface of the skin and myocardium, 25 the adhesion energy of the hydrogel on their surfaces is higher than that of other tissue substrates.…”

Recent Advances in Mechanical Reinforcement of Zwitterionic Hydrogels

“…When HEMA:SBMA = 2:3, the hydrogel exhibited a tensile strain of 10.0 mm/mm, a tensile stress of 60 KPa, and a compressive stress of 37 MPa at 98% compressive strain. Li et al [ 113 ] added waterborne polyurethane (PU) emulsion microspheres to the p(SB 3 MA 2 -co-AAm) hydrogel. The PU chains were stretched during stress application, providing additional mechanical energy dissipation and more entanglement and friction with the copolymer network.…”

Assembled caseins as crosslinkers for tough, adhesive and self-healing hydrogels towards flexible sensors

“…5e and f). [44][45][46][47][48][49] The excellent sensitivity may be related to the ionized water channels separated by EG molecules. To explain the above statement, electrochemical impedance spectra of the C 3 AE 3 P hydrogel were recorded.…”