Single Ice Crystal Growth with Controlled Orientation during Directional Freezing

Area of Science:

• Materials Science
• Crystallography
• Biomaterials Engineering

Background:

• Ice growth is crucial for creating hierarchical porous microstructures.
• Understanding ice orientation during freezing is key for architectural control in porous biomaterials.
• Previous in situ observations had limitations in controlling ice orientation relative to thermal gradients.

Purpose of the Study:

• To conduct an in situ study of solid/liquid interface morphology evolution during directional solidification of single crystal ice.
• To investigate ice growth habits in poly(vinyl alcohol, PVA) solutions with controlled ice orientation.
• To provide a clearer insight into the inherent ice growth habit in polymeric aqueous systems for biomaterial design.

Main Methods:

• Directional solidification of single crystal ice in poly(vinyl alcohol, PVA) solutions.
• In situ observation of ice growth with the C-axis perpendicular to both thermal gradient and incident light.
• Quantitative characterization of lamellar spacing, tilt angle, and tip undercooling.

Main Results:

• Multifaceted morphology and V-shaped lamellar morphology of ice were observed in situ for the first time.
• Detailed quantitative data on lamellar spacing, tilt angle, and tip undercooling were obtained.
• The study established a controlled environment for observing ice growth habits.

Conclusions:

• The observed morphologies provide new insights into ice growth habits in polymeric aqueous systems.
• These findings are expected to significantly impact the future design and optimization of porous biomaterials.
• Controlled in situ observation is vital for understanding and manipulating ice growth for advanced material fabrication.