Guest Molecule Diffusion-Regulated Morphological Evolution of Gas Hydrate Crystals.

Area of Science:

• Materials Science
• Chemical Engineering
• Crystallography

Background:

• Controlling crystal morphology is crucial for material applications, especially for gas hydrates formed at gas-liquid interfaces.
• Gas hydrates present challenges due to immiscible precursors and film-like growth.
• Existing methods lack precise control over hydrate crystal shape.

Purpose of the Study:

• To develop a method for controlled gas hydrate crystal morphology.
• To investigate the growth mechanisms and kinetics of gas hydrates.
• To explore the potential for shape engineering in host-guest solid systems.

Main Methods:

• Utilized sodium dodecyl sulfate solutions to inhibit interfacial film growth.
• Employed presettled microcrystals as seeds for controlled nucleation and growth in aqueous media.
• Applied X-ray computed tomography (CT) scanning for quantitative growth kinetics analysis.
• Integrated theoretical modeling to understand growth mechanisms.

Main Results:

• Achieved flexible control over hydrate morphology, producing polyhedral, dendritic, and a novel hopper-shaped form.
• Demonstrated that hydrate growth is dominated by mass transfer, regardless of crystal shape.
• Observed accelerated growth kinetics with increased supersaturation, promoting transitions to hopper and dendritic morphologies.
• Showcased how morphology amplifies surface area to meet mass transfer demands.

Conclusions:

• Seeded nucleation and interfacial transport control offer a versatile platform for gas hydrate shape engineering.
• The findings facilitate hydrate-related applications and provide insights for other crystal growth systems.
• This approach enables precise morphology control for targeted functional properties.