Redox-responsive self-healing materials formed from host–guest polymers

Abstract

Expanding the useful lifespan of materials is becoming highly desirable, and self-healing and self-repairing materials may become valuable commodities. The formation of supramolecular materials through host–guest interactions is a powerful method to create non-conventional materials. Here we report the formation of supramolecular hydrogels and their redox-responsive and self-healing properties due to host–guest interactions. We employ cyclodextrin (CD) as a host molecule because it is environmentally benign and has diverse applications. A transparent supramolecular hydrogel quickly forms upon mixing poly(acrylic acid) (pAA) possessing β-CD as a host polymer with pAA possessing ferrocene as a guest polymer. Redox stimuli induce a sol−gel phase transition in the supramolecular hydrogel and can control self-healing properties such as re-adhesion between cut surfaces.

Chemo-responsive, self-oscillating gels that undergo biomimetic communication

“…Currently, severed pieces of self-healing gels or networks can only form bonds when these pieces are brought together by an external agent (e.g., placed in contact via human intervention). [95][96][97][98] To the best of our knowledge, there is no example of synthetic materials that bring themselves together as the first step in the self-healing process. Notably, the sides of the isolated BZ gels can potentially be functionalized with reactive groups that would promote bond formation as the separate pieces come within a critical distance of each other.…”

Stretchable Multiresponsive Hydrogel with Actuatable, Shape Memory, and Self‐Healing Properties

“…And multiresponsive supramolecular hydrogel which consists of polyacrylic acid, phenylboronic acid, and agar presents shape memory functionality under triple stimuli 13. However, capability of current responsive hydrogels is commonly too monotonous to meet various requirements, either showing one functionality upon individual trigger,14 or multiresponsive behaviors all resulting in same property 15. Meanwhile, stretchability of hydrogel, which could be enhanced by interpenetrating network structure,16 acts an essential role in researches referring to soft robotics, electronic skin, and artificial muscle 17.…”

Self‐Adjustable Adhesion of Polyampholyte Hydrogels

“…Developing adhesives that possess the ability of quick, strong, and reversible adhesion to hydrogels and biological tissues regardless their net charge identity will substantially promote the application of hydrogels in biomedical applications. Several research groups have tried to develop different adhesive hydrogels based on surface modification, [6] mechanical interlocking, [7] making composites, [8] supramolecular recognition, [9] and nano-particles. [10,11] But these approaches have limitations in practical applications, such as lengthy and complicated way of processing, lack of water resistivity and universality, inability in non-residual removal, etc.…”