Wettability behavior of DTMS modified SiO₂: Experimental and molecular dynamics study

Area of Science:

• Surface Chemistry
• Materials Science
• Computational Chemistry

Background:

• Controlling the surface properties of silica (SiO2) is crucial for various applications.
• Understanding the molecular mechanisms behind surface modification is essential for tailored material design.

Purpose of the Study:

• To investigate the wetting behavior of SiO2 modified with dodecyltrimethoxysilane (DTMS).
• To elucidate the role of DTMS grafting on SiO2 surface hydrophobicity using experimental and simulation methods.
• To analyze the impact of temperature on the wetting behavior of modified and pristine SiO2 surfaces.

Main Methods:

• Experimental characterization of surface wetting.
• Molecular dynamics (MD) simulations to analyze molecular interactions and structure.
• Contact angle (CA) measurements and fitting.
• Analysis of ionic pairs, concentration distribution, molecule orientation, and interfacial interaction energy.

Main Results:

• DTMS chemically bonds to the SiO2 surface, significantly increasing hydrophobicity.
• A maximum contact angle of 158.2° was achieved at a 25% DTMS grafting rate.
• DTMS grafting disrupts interfacial hydrogen bonding and alters hydration structure, leading to increased CA.
• Hydrophobic SiO2 shows a decreased CA with increasing water temperature, while pristine SiO2 shows an opposite trend due to differing interfacial interactions.

Conclusions:

• DTMS modification offers an effective strategy for tuning SiO2 surface wettability.
• The study provides insights into the molecular-level mechanisms governing the wetting behavior of modified SiO2.
• Findings contribute to a deeper understanding of surface wetting adjustments for SiO2-based materials.