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Synthesis and Characterization of Supramolecular Colloids
Published on: April 22, 2016
Fluoroalkyl-functionalized silica particles: synthesis, characterization, and wetting characteristics
Raymond Campos1, Andrew J Guenthner, Timothy S Haddad
1ERC, Inc., Space & Missile Propulsion Division, Air Force Research Laboratory, Edwards AFB, California 93524, United States.
Langmuir : the ACS Journal of Surfaces and Colloids
|July 7, 2011
Summary
Researchers developed nonwetting surfaces using fluoroalkyl-functionalized silica particles. The most effective method involved grafting monofunctional chlorosilanes, creating surfaces with dominant geometric properties for liquid repellency.
Area of Science:
- Materials Science and Engineering
- Surface Chemistry
- Nanotechnology
Background:
- Development of nonwetting surfaces is crucial for various applications.
- Silica particles offer a versatile platform for surface modification.
- Fluoroalkyl groups are known for imparting hydrophobic and oleophobic properties.
Purpose of the Study:
- To prepare fluoroalkyl-functionalized silica particles for nonwetting surfaces.
- To investigate the efficiency of different chlorosilane functionalities (mono-, di-, trifunctional) for surface coverage.
- To understand the influence of surface grafting and residual silanol content on wetting properties.
Main Methods:
- Surface treatment of fumed and precipitated silica with fluoroalkyl-functional chlorosilanes.
- Optimization of grafting conditions using monofunctional chlorosilanes with dimethylamine under anhydrous conditions.
- Characterization using Fourier transform infrared (FT-IR) spectroscopy, elemental analysis, thermogravimetric analysis (TGA), and nitrogen adsorption isotherms.
- Evaluation of moisture uptake and liquid wetting properties via water uptake measurements and dynamic contact angle analysis.
Main Results:
- Monofunctional chlorosilanes, in the presence of dimethylamine, provided the most effective surface grafting.
- Characterization confirmed covalent attachment and provided insights into grafting densities and surface geometry.
- While residual silanol content influenced moisture uptake, surface geometry was identified as the dominant factor for liquid repellency.
Conclusions:
- Fluoroalkyl-functionalized silica particles can be effectively prepared for nonwetting applications.
- Surface grafting of monofunctional chlorosilanes offers superior performance.
- The geometric characteristics of the modified surface play a primary role in achieving hydrophobic and oleophobic properties.
