Interfacial behavior from the atomic blueprint: Machine learning-guided design of spatially functionalized α-SiO₂...

Area of Science:

• Materials Science
• Surface Chemistry
• Computational Chemistry

Background:

• Alpha-quartz surfaces functionalized with hydroxyl (OH) and methyl (CH3) groups are crucial for catalysis, coatings, and energy applications.
• Interfacial properties are strongly influenced by the arrangement of these surface groups, particularly at solid-liquid interfaces.
• Existing models often assume homogeneous surface functionalization, neglecting atomic-scale organization.

Purpose of the Study:

• To investigate the hypothesis that the spatial distribution of OH and CH3 groups, beyond composition, dictates surface stability and interfacial behavior.
• To explore the role of functional group patterning on the alpha-quartz (0001) surface.
• To establish a link between functional group arrangement and interfacial properties for rational material design.

Main Methods:

• A multi-scale simulation workflow combining density functional theory (DFT), ab initio molecular dynamics (AIMD), and machine-learned force fields (MLFFs).
• Evaluation of spatial patterns of OH/CH3 functionalization on the alpha-quartz (0001) surface.
• Analysis of mixing energy, hydrogen bonding networks, and vibrational properties.

Main Results:

• Spatial patterning significantly influences surface stability and interfacial structure.
• A favored unpaired configuration (around 67% substitution) shows isolated groups forming secondary hydrogen bonds via reorientation.
• This rearrangement leads to a blue shift in vibrational stretching frequencies, indicating weaker hydrogen bonding, an effect absent in clustered arrangements.

Conclusions:

• The spatial arrangement of surface functional groups is a critical factor in determining the stability and interfacial behavior of alpha-quartz.
• Unpaired functionalization patterns can lead to unique hydrogen bonding networks and altered vibrational properties.
• This research provides fundamental insights to guide the rational design of functionalized silica materials for diverse applications in colloid and interface science.