Ultrafast Self-Healing, Highly Stretchable, Adhesive, and Transparent Hydrogel by Polymer Cluster Enhanced Double Networks for Both Strain Sensors and Environmental Remediation Application

Abstract

Stretchable, healable, biocompatible, and conductive hydrogels are one of the promising candidates for both wearable electronics and environmental remediation applications. To date, the design of hydrogels that integrate ultrafast self-healing with high efficiency (seconds), high stretchability, and biocompatibility and reversibility into one system is not an easy task. Herein, we demonstrate a general oxidation approach to accelerate the hydrogelation of hPEI-based double network gels via the generation of fluorescent polymer clusters at room temperature or triggered by the heating–cooling process. The resulting ohPEI hydrogel has the merit of biocompatibility over most reported hPEI hydrogels for strain sensors. It shows a high conductivity (1.3 S/m), an ultrafast self-healing ability (<3 s, 98% healing efficiency within 60 s), a high stretchability (∼1850 and ∼7000% in deformation), and reversible adhesivity on various material surfaces. The excellent performance of the hydrogel is ascribed to the cooperative and hierarchical interactions of four types of dynamic combinations, including the reversible borate bond, hydrogen bonding, electrostatic interaction, and polymer cluster interactions. The reversible fabrication process by the one-spot method (just by simple mixing of the components) and superior properties of the hydrogel make it an ideal candidate for a wearable strain sensor to monitor human motions and physiological activities. Moreover, it is also a good hydrogel absorbent for phase separation absorption of volatile organic compounds with a high capacity (for acetone: 4.75 g g–1), reusability, and an easy handling process.

Desirable Strong and Tough Adhesive Inspired by Dragonfly Wings and Plant Cell Walls

“…Moreover, the presence of the typical B−O−C peak of PWP@PBA at 1336 cm −1 indicated the occurrence of a covalent reaction between PBA and wood under the curing condition of the adhesive. 74,75 The mechanical properties (shear resistance and brittleness) of SM-based adhesives were tested by stretching standard plywood specimens (Figure 6a Compared to SM adhesive, the dry and wet shear strengths of SM/MoS 2 @TA increased to 2.01 and 1.08 MPa, respectively. This improved effect was attributed to the nanostrengthening effect of the ordered stacked nanosheets (inspired vividly by dragonfly wings) and the cross-linking of TA anchored on the nanosheets to SM through chemical interactions.…”

Recent advances in adhesive materials used in the biomedical field: adhesive properties, mechanism, and applications

“…Yu et al synthesized a novel double-network hydrogel system based on PVA and the oxidation of polyethylenimine. 198 Based on the properties of the polyethylenimine clusters, the study was carried out by introducing a simple supramolecular crosslinking agent, and a novel in situ oxidation method was developed to fabricate the first double network hydrogel interface sensor based on polymer nanoclusters. The hydrogel has good transparency (490%, 500-800 nm) and high electrical conductivity (1.3 s m À1 ), which can be self-repaired and stretched rapidly in 1 s. The repair efficiency and tensile growth rate of the hydrogel were as high as 98% and 7000%, respectively after 60 s. The response time and recovery time to pressure were both o120 ms.…”

Research progress of flexible hydrogel sensor

“…Hou et al [17] successfully prepared ohPEI (polyethyleneimine)/PVA-based hydrogels with ultrafast self-healing ability, adhesion and conductivity. 3, 5-Dicarboxyphenylboronic sodium (DCBS) was introduced into the covalent network of PEI and PVA as a supramolecular cross-linker.…”