Sol-Gel Process

The sol-gel process is a wet-chemical method that can be used to create coatings and surface modifications in a cost-effective manner. In principle, the process is suitable for a wide range of base materials (metal, glass, plastic, wood, paper & cardboard, textiles, etc.). By varying and modifying the precursors, the properties of the coating and, consequently, the surface characteristics of the coated materials can be significantly influenced and controlled. The incorporation of inorganic and organic components enables additional functionalities, such as antibacterial effects and the targeted release of active ingredients.

Possible fields of application of the sol-gel process:

• mechanical protection (wear, scratch resistance, friction)
• barrier function (corrosion resistance, permeation)
• interface interactions (setting of hydrophobicity/oleophobicity, biocompatibility)
• functional integration (photocatalysis, antimicrobial layers, drug release)
• optical function (reflection, absorption, decoration)
• electrical function (electrical insulation, conductivity)

Basic principle of the sol-gel process:

As a precursor, a liquid ‘sol’ (a colloidal solution of inorganic oxide particles, such as SiO₂ or TiO₂ nanoparticles) is used as the starting material in the sol-gel process. Using conventional coating techniques (such as dipping, spraying, spinning, doctor-blading, etc.) coatings can be easily and cost-effectively applied to a variety of surfaces and substrates. Even complex geometric shapes (e.g., internal and/or external coating of pipes and capillaries) can be successfully realized using the sol-gel process.

The surface of the substrate is first wetted with the sol. Condensation reactions (polymerization) then lead to the three-dimensional cross-linking of the sol particles, resulting in the formation of a gel. This entire process is commonly known as the ‘sol-gel process.’ The gel can be hardened through a brief sintering process, forming glass-like layers that are highly scratch-resistant. Since the sol-gel process can be performed at room temperature and normal pressure, it is suitable for coating temperature-sensitive substrates and even embedding living microorganisms and enzymes.

Due to the large number of potential precursors as well as the possibility of chemical and physical modification, the application potential of sol-gel coatings for modifying surface properties seems almost unlimited. This means that a wide variety of materials can be functionalized, enhancing their performance characteristics.

As an alternative to the production of thin inorganic layers, the colloidal sol can also be further processed into 3-dimensional gel bodies, powders, and granules, and in this way, active ingredients and, for example, living microorganisms can be embedded in gel bodies.

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We are her to help:

We would be pleased to collaborate with you on a research and development project or provide third-party services to develop a coating solution for your specific application. In addition to performing coatings in small batches and pilot scale, we also offer the synthesis and modification of inorganic sols. Feel free to reach out to us with your specific synthesis request—we are happy to assist.

Our Expertise:

• development and synthesis of coating solutions based on inorganic sols
• extensive experience in the development of sol-gel coatings for targeted surface modification of flexible substrates (e.g., textiles, paper, polymer films) as well as rigid materials (e.g., wood, plastic, glass, and metal)
• continuous coating of flexible substrates such as paper, films, and textiles (with a maximum width of 25 cm)
• coating and encapsulation processes for prototypes and small-scale production
• surface and coating analysis and characterization

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ANSPRECHPARTNER:
Dr. Helfried Haufe
Fachsektion Dresden – “Funktionelle Schichten”
Tel.: 0351 / 2695 344
E-Mail: dresden@gmbu.de