Effect of Interfacial Bonding on Interphase Properties in SiO2/Epoxy Nanocomposite: A Molecular Dynamics Simulation...

Area of Science:

• Materials Science
• Computational Chemistry
• Polymer Science

Background:

• Nanocomposites offer enhanced properties through nanoparticle reinforcement.
• The interphase region in nanocomposites is crucial for load transfer and overall performance.
• Understanding interfacial bonding effects is key to designing advanced materials.

Purpose of the Study:

• To investigate the influence of interfacial bonding on the interphase properties of silica-epoxy nanocomposites.
• To elucidate the structural and dynamic changes induced by covalent and non-covalent interfacial interactions.
• To determine the critical bonding ratio for synchronous glass transitions between the interphase and matrix.

Main Methods:

• Atomistic molecular dynamics simulations were employed.
• Analysis of structural properties including mass density, chain orientation, and thermal stability.
• Investigation of atomic mobility using mean-square displacement and immobile atom fractions.

Main Results:

• Covalent bonding broadens and strengthens the interphase, increasing thermal stability and glass transition temperature (Tg) by ~21 K.
• Interfacial bonding influences volume thermal expansion, particularly near or above Tg.
• A critical bonding ratio of 5.8% was identified for synchronous atomic mobility between interphase and matrix.

Conclusions:

• Interfacial bonding significantly alters interphase properties and nanocomposite behavior.
• Asynchronous glass transitions occur when the bonding ratio deviates from 5.8%, impacting matrix behavior.
• Simulation results provide insights into tailoring nanocomposite properties through controlled interfacial interactions.