Beyond Sol-Gel: Molecular Gels with Different Transitions.

Area of Science:

• Materials Science
• Supramolecular Chemistry
• Physical Chemistry

Background:

• Molecular gels are characterized by the formation of a three-dimensional network through non-covalent interactions of small molecules.
• The most common transition observed in molecular gels is the reversible sol-gel transition, driven by temperature changes.
• Historically, gel morphology and gel-to-crystal transitions were noted, but recent research reveals more complex phase behaviors.

Purpose of the Study:

• To review and survey molecular gels exhibiting phase transitions beyond the standard sol-gel transformation.
• To highlight the diversity of transitions, including gel-to-gel, gel-to-crystal, liquid-liquid phase separations, eutectic transformations, and syneresis.
• To provide a comprehensive overview of the complex phase behavior of molecular gels.

Main Methods:

• Literature review and survey of published research on molecular gels.
• Analysis of reported experimental data on various gel transitions.
• Categorization and discussion of different types of observed phase transitions.

Main Results:

• Molecular gels can exhibit multiple transitions beyond the simple sol-gel equilibrium.
• Reported transitions include gel-to-gel, gel-to-crystal, liquid-liquid phase separation, eutectic transformations, and syneresis.
• The nature and conditions of these transitions are dependent on the specific molecular structure and formation environment.

Conclusions:

• The phase behavior of molecular gels is more complex than previously assumed, involving a wider array of transitions.
• Understanding these diverse transitions is crucial for controlling gel properties and designing new materials.
• Further research into the mechanisms and applications of these complex transitions is warranted.