Inflation Negative Compressibility during Intrusion-Extrusion of a Non-Wetting Liquid into a Flexible Nanoporous...

Area of Science:

• Materials Science
• Condensed Matter Physics
• Chemistry

Background:

• Negative compressibility (NC) describes materials that expand in one or more dimensions when compressed.
• NC is a rare phenomenon with significant potential for technological applications.
• Existing NC effects are typically small in magnitude.

Purpose of the Study:

• To investigate and achieve a significantly enhanced negative compressibility effect.
• To explore the NC phenomenon in a flexible porous material using a non-wetting liquid.
• To quantify the NC coefficients in the studied system.

Main Methods:

• Intrusion-extrusion experiments with water and a hydrophobic metal-organic framework (MOF), Cu2(tebpz).
• In situ high-pressure neutron scattering to observe structural changes.
• Density Functional Theory (DFT) calculations to support experimental findings.

Main Results:

• A gigantic negative compressibility effect was observed, exceeding previously reported values by over an order of magnitude.
• The Cu2(tebpz) MOF expanded in the 'a' and 'c' directions upon water penetration.
• NC coefficients greater than 10^3 TPa^-1 were achieved.

Conclusions:

• The water-infused hydrophobic MOF system demonstrates unprecedented negative compressibility.
• The findings suggest a new approach to designing materials with extreme negative linear compressibility.
• The methodology is applicable to a broader range of materials for achieving high NC coefficients.