Physical hydrogels in existing polymers composed of non-covalent interaction networks are favored due to their controllable composition and environmental friendliness, and are therefore used as adhesives, artificial tissues and soft machinery. However, these gels have poor mechanical strength and water resistance. The current method of preparing hydrogels is primarily a cryogels, which is a complex process and requires insufficient adjustment of the conformation of polymers. In view of this, researchers Qiu Dong and Qiao Yan from State Key Laboratory of Polymer Physics and Chemistry, Institute of Chemistry, Chinese Academy of Sciences, et al proposed a solvent exchange strategy to construct a class of external gels by utilizing non-covalent bonds, which have the advantages of modulability and reversibility.
Main points of this article:

1) According to the exchange from good solvent to bad solvent, the interactions between the polymer and the interpolymer are first inhibited and then restored, leading to polymer dissolution and crosslinking, respectively.

2) The key to this method is a good solvent, which is conducive to the conformation of tensile polymer to homogenize the network and form a cross-linked hydrogel network. It has significant stiffness, toughness and anti-expansion properties, so it has underwater adhesion properties.

In summary, the exosgels emphasize a simple but efficient strategy of changing the solvent to achieve non-covalent interactions that lead to the rational design of enhanced hydrogels and hydrogel-based soft materials.







References:



Xu, L., et al., A Solvent‐Exchange Strategy to Regulate Noncovalent Interactions for Strong and antispecifyproduct Hydrogels. Adv. Mater. 2020, 2004579.



https://doi.org/10.1002/adma.202004579



Source: Theory of Oddities



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