Triggering gelation in a chemically active solvent

A recent study published in Chemical Communications reports a rare case of a gel in which the solvent plays an active role in the gelation process.
The solvent controls the chemical reactions responsible for the gel formation. The lifespan of the gel is four days. However, swelling expands the lifetime up to seven months, during which the gel matrix is also changing.
Published
26.10.2021

In nature, molecular assemblies form temporarily as they constantly exchange energy and matter with the environment. Novel artificial assembled systems mimic natural systems' dynamic character by utilising “chemical fuels”, which activate the molecular building blocks and induce their self-assembly. Depletion of the fuel causes the disassembly of the system, while the addition of extra fuel can regenerate the assembly/disassembly cycle. Such dynamic systems do not depend only on fuelled systems, but their lifetime can be controlled, for example, by enzymatic or chemical catalysis and resulting pH change.

“Gels are soft materials that consist of a solvent (major component) immobilized in an elastic, cross-linked, three-dimensional network of fibres (minor component). The fibrous network originates from the assembly of the gelator molecules. Until recently, the materials’ properties were immediately related to the gelator properties and the gelation procedure. But what about the solvent? Is there a way in which the solvent can actively participate in the construction of dynamic gels?” explains Postdoctoral Researcher Efstratios Sitsanidis from the Ģֱ.

In the developed gelation system, the lifetime and matrix of the gel are affected by a chemically active solvent. Treatment of the material introduces control of its lifetime and internal structure. “This is a rare case of gelation which can lead to new approaches for the development of dynamic assembled systems,” says Dr Sitsanidis.

A rare gel system as a proof of concept

The Synthetic and Structural Nanochemistry group led by Professor Maija Nissinen, in collaboration with Professor David Smith, University of York, UK focused on a new research concept towards gel systems that assemble in a dynamic way. “We recently developed a gel system whose self-degradation time can be controlled by the change in physical conditions. The degradation of our system lies in a set of chemical reactions which are antagonists to one another. Indeed, the primary solvent is chemically transformed to a secondary solvent responsible for the collapse of the gel. This is the first reported case of an active solvent in gel systems”, describes Doctoral Researcher Romain Chevigny.

The research was published in on the 15 September 2021.

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