Ran Rong of Sichuan University/Chen Qiang of Wenzhou Institute of National University of Science and Technology: Turning non-sticky hydrogels into tough adhesives

[Introduction] Achieving a strong bond between the hydrogel and the solid surface is essential for the development of emerging high-complexity soft and hard mixing equipment.
However, due to its weak interfacial interaction with solid surfaces and negligible mechanical dissipation, this is extremely challenging for many non-viscous hydrogels.
【Abstract】 Recently, the team of Professor Ran Rong of Sichuan University/Professor Qiang Chen of Wenzhou Research Institute of the University of Chinese Academy of Sciences (National University of Science and Technology) reported a phase separation strategy that can transform the traditional non-viscous hydrogels into those suitable for various solid surfaces.
Super glue without chemical treatment.
Equilibrating the hydrogel in a mixture of good solvents and poor solvents can cause phase separation, resulting in a significant increase in the volume fraction of the polymer on the surface of the gel and most of the gel.
The high-density polymer chains on the surface of the gel help to form a dense array of non-covalent bonds with the solid surface, thereby improving the inherent work of adhesion and facilitating the transfer of force from the crack front to the bulk gel.
At the same time, the phase separation structure in the bulk gel allows significant mechanical dissipation during interface separation.
This synergy helps to improve the toughness of the interface.
The toughness of more than 1000 J m-2 is instant and repeatable.
After more than 100 attachment/detachment cycles, there is no obvious loss of interface toughness.
This simple and reproducible phase separation method is also universal, can be induced by a variety of mixed solvents, and is suitable for many types of common non-viscous hydrogels to achieve a hard and separable gel-solid bond .
Related papers are published in "Journal of Materials Chemistry A" with the title Transforming Non-Adhesive Hydrogels to Reversible Tough Adhesives via Mixed-Solvent-Induced Phase Separation.
[Main image] Figure 1.
Schematic diagram of the phase separation strategy to achieve firm adhesion between the brittle hydrogel and the solid surface.
Figure 2.
Adjusting PAAm gel from a non-sticky gel to a tough adhesive through phase separation.
Figure 3.
The effect of phase separation on the surface and overall structure of PAAm hydrogels.
Figure 4.
The effect of phase separation on the mechanical properties of PAAm hydrogels.
Figure 5.
Effective contact to achieve hard gel-solid adhesion.
Figure 6.
The versatility and repeatability of a hard gel-solid bond.
Figure 7.
Hard gel-solid adhesion makes soft and rigid mixing equipment possible.