Microthermogravimetry of a single microcapsule using silicon microresonators

Area of Science:

• Materials Science
• Nanotechnology
• Chemical Engineering

Background:

• Polyurethane microcapsules are used for various applications.
• Characterizing microcapsule thermal events is crucial for material performance.
• Conventional methods like thermogravimetric analysis (TGA) have limitations in resolving individual events.

Purpose of the Study:

• To develop a high-resolution method for detecting microcapsule thermal events.
• To investigate the temperature-dependent behavior of chlorobenzene-containing polyurethane microcapsules.
• To compare the cantilever method with conventional thermogravimetric analysis (TGA).

Main Methods:

• A silicon cantilever was used as a sensor to detect microcapsule events.
• The resonance frequency of the cantilever was measured as temperature changed.
• Polyurethane microcapsules containing chlorobenzene were analyzed.

Main Results:

• Steplike increases in resonance frequency were observed at 109°C (capsule rupture) and 270°C (polyurethane degradation).
• The cantilever method provided sharper transitions compared to TGA.
• Individual rupture temperatures of multiple microcapsules were distinguishable.
• Increased chlorobenzene permeability in the polyurethane shell lowered the rupture temperature.

Conclusions:

• A silicon cantilever is a sensitive tool for identifying individual microcapsule rupture events.
• This method offers superior resolution over TGA for characterizing microcapsule thermal transitions.
• Microcapsule permeability significantly influences its thermal stability and rupture temperature.