Synergistic Effects of IMX-104 Components in Membrane Absorption: A Computational Study

Area of Science:

• Environmental Science
• Toxicology
• Computational Chemistry

Background:

• Insensitive munitions (IM) like IMX-104 are designed for enhanced safety.
• Synergistic toxicity of 2,4-dinitroanisole (DNAN) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) in IMX-104 raises environmental and health concerns.
• The underlying mechanism of this synergistic toxicity remains largely unknown.

Purpose of the Study:

• To investigate the membrane absorption of DNAN and RDX as a key step in understanding their synergistic toxicity.
• To elucidate the role of RDX in the membrane adsorption of DNAN within IMX-104 formulations.

Main Methods:

• Umbrella sampling technique was employed to calculate key absorption parameters.
• Calculated permeability coefficient, transmembrane time, and liposome-water partition coefficient.
• Analyzed free-energy curves to understand molecular interactions within membranes.

Main Results:

• RDX promotes the membrane absorption of the more toxic component, DNAN.
• RDX is absorbed by the membrane prior to DNAN.
• Strong van der Waals interactions between DNAN and RDX cause DNAN to aggregate around RDX within the membrane.
• RDX stabilizes DNAN within the membrane, leading to an 11% increase in DNAN absorption compared to pure DNAN systems.

Conclusions:

• The membrane adsorption stage is a likely contributor to the synergistic toxicity of IMX-104.
• RDX's presence significantly enhances DNAN's membrane permeability and retention.
• Understanding these molecular interactions is crucial for assessing the environmental and health risks of IMX-104.