Novel Solid Encapsulation of Ethylene Gas Using Amorphous α-Cyclodextrin and the Release Characteristics

Area of Science:

• Materials Science
• Chemical Engineering
• Physical Chemistry

Background:

• Controlled release technologies are crucial for various applications.
• Cyclodextrins (CDs) are known for their ability to form inclusion complexes with guest molecules.
• Ethylene gas has specific applications requiring controlled delivery.

Purpose of the Study:

• To investigate the encapsulation of ethylene gas into amorphous alpha-cyclodextrins (α-CDs).
• To characterize the resulting inclusion complexes (ICs).
• To determine the controlled release behavior of ethylene from the ICs under varying relative humidity (RH).

Main Methods:

• Encapsulation of ethylene gas into amorphous α-CDs at different moisture contents (low and high) under pressure.
• Characterization of inclusion complexes using X-ray diffractometry (XRD), CP-MAS (13)C NMR, and Scanning Electron Microscopy (SEM).
• Analysis of ethylene release kinetics using Avrami's equation under various RH conditions.

Main Results:

• Ethylene concentrations in the ICs varied based on moisture content, with higher concentrations observed in low moisture content α-CDs.
• Ethylene release rate increased with increasing relative humidity.
• Avrami's equation analysis indicated no significant difference in release constant (k) and parameter (n) between low and high moisture content α-CDs at any given RH.
• NMR confirmed the presence of ethylene within the α-CD matrix.

Conclusions:

• Amorphous α-CDs can effectively encapsulate ethylene gas.
• The release of ethylene from α-CDs is controllable by adjusting relative humidity.
• Moisture content during encapsulation does not significantly impact the release kinetics under the studied conditions.