Unique Crystallization Characteristics of Pickering High Internal Phase Emulsion Templated Porous Constructs

Area of Science:

• Materials Science
• Polymer Science
• Nanotechnology

Background:

• Understanding polymer crystallization is crucial for material properties.
• Porosity and nanoparticle inclusion can significantly influence polymer chain dynamics.
• Poly(ε-caprolactone) (PCL) is a versatile biodegradable polymer with potential applications in energy storage.

Purpose of the Study:

• To investigate the crystallization behavior of poly(ε-caprolactone) (PCL) in nonporous and porous nanocomposite constructs.
• To elucidate the effects of porosity, cross-linking, and modified fumed silica nanoparticles (mSiNP) on PCL thermal properties and crystallization kinetics.
• To explore the potential of these PCL constructs as energy storage materials.

Main Methods:

• Fabrication of porous cross-linked PCL nanocomposite constructs via Pickering high internal phase emulsions (HIPEs) stabilized by mSiNP.
• Differential Scanning Calorimetry (DSC) to analyze thermal properties and crystallization behavior.
• X-ray Diffraction (XRD) to study changes in crystal structure.
• Evaluation of crystallization kinetics using Jeziorny, Ozawa, and Mo theories under nonisothermal conditions.

Main Results:

• Cross-linking and mSiNP inclusion in nonporous PCL constructs diminished crystallization temperature and kinetics, indicating suppressed polymer chain mobility.
• Introduction of porosity led to significant supercooling, with crystallization temperatures as low as -24 °C.
• Porous constructs exhibited complex crystallization mechanisms deviating from theoretical models, influenced by chain immobility and wall thickness heterogeneity.

Conclusions:

• Porosity and cross-linking significantly impact PCL crystallization behavior, leading to complex mechanisms.
• The observed melting-crystallization phenomena in these PCL nanocomposites suggest potential for energy storage applications.
• Further research into similar high heat capacity systems could expand their utility in thermal energy storage.