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Fumed Silica - Hydrophilic and Hydrophobic

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Product Overview


For over 70 years Evonik’s™ AEROSIL® has been a market leading brand of fumed silica. With a unique range of both hydrophilic and hydrophobic grades available the number of applications are endless. Fumed (pyrogenic) silica is composed of synthetic silicon dioxide (SiO2) which is entirely amorphous, eliminating the risks posed by crystalline silica.

One of the main applications for fumed silica is increasing the viscosity, pseudoplasticity and thixotropy of a wide range of liquid systems. However there are many more applications besides this common use case. Evonik’s™ AEROSIL® range is the most extensive range of fumed silica on the market, with many of their products tailored for particular applications. The versatility of AEROSIL® means that it can be found all around us, from the paints on our walls to the fertilizers on our crops. Read on to find out more about this exciting product range.


Brochures & Technical Literature

AEROSIL® - Fumed Silica Technical Overview

A complete overview of the Evonik™ AEROSIL® range.

download Download PDF 25 MB
Successful Use of AEROSIL® Fumed Silica in Liquid Systems

A brochure detailing the use of AEROSIL®  in liquid systems including best practices for dispersion.

download Download PDF 2 MB
Speciality Silica as Flow Aid, Anticaking Agent and Carrier Substance

AEROSIL® and SIPERNAT® are both widely used for improving the flow characteristics and anti-caking of powders, and can be used as a carrier for liquids.

download Download PDF 353 KB

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Product Features
  • Chemically inert synthetic amorphous silica. High purity
  • Available in hydrophilic and surface-treated hydrophobic grades
  • A wide range of surface areas are available
  • Broad legislative approvals on many grades e.g. indirect food contact
  • Mixed fumed silica/metal oxide grades available
Product Benefits
  • Efficient rheology control in a wide range of simple and complex liquid systems. Imparts viscosity, pseudoplasticity and thixotropy. Stabilises pigments and prevents sagging.
  • Provides effective free flow and anti-caking behaviour. Can be used as a solid carrier for liquids.
  • Improves mechanical and optical properties of silicone rubber.
  • Improves anti-corrosion performance of protective and marine coatings. Reduces moisture sensitivity and increases hydrophobicity. Useful in silicone sealants for extending shelf life for example.
  • Anti-blocking agent for PET films.
  • Many more applications: greases, batteries, agrochemicals etc.
Typical Applications
  • Rheology and thixotropy control in coatings, inks, sealants & adhesives
  • Improving anti-corrosion properties of protective coatings
  • Scratch resistance in coatings
  • Thickening and hydrophobicity of greases
  • Electrolyte immobilization in lead-acid batteries
  • Anti-settling agent in pigment dispersions and suspension concentrates
  • Solid carrier for liquids
  • Mechanical and optical enhancement of silicone rubbers
  • Impart free-flow and anti-caking properties in powders
  • Metal and glass polishing
Related Technical Articles
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Defoamers: Speciality Silica

Foam in industrial applications such as coatings and detergents can impact the quality of the finished product and interfere with manufacturing; Therefore the market for making defoamers that remove this issue is large. This article discusses how defoamers work and what makes a good defoamer as well as how speciality silica can benefit a defoamer formulation.

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New Easy-to-Disperse (E2D) AEROSIL® fumed silica grades

Fumed silica is a well-established rheology modifier in coatings, adhesives and sealants due to its thixotropic properties at low additions, however, it can be difficult to wet out and requires energy-intensive mixing to ensure proper dispersion. Evonik's new Easy-to-Disperse (E2D) range addresses these issues.

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Featured grades with technical datasheets

A brief overview of the key grades with their Technical Datasheets (TDS) is given below.

If you are looking for a Safety Datasheet (SDS), Product Safety Information (PSI) or an alternate grade, then please get in touch or request a sample.

Key points at a glance:

  • Hydrophilic surface with a medium-high surface area. It is one of the most widely used grades of fumed silica.
  • Efficient pseudoplastic rheology build and thixotropic behaviour in a wide range of polar and non-polar solvents and polymers.
  • Animal feed grade available. Manufactured according to FAMI-QS guidelines. 
download AEROSIL 200 technical datasheet 656 KB

Key points at a glance:

  • Low-medium surface area hydrophilic fumed silica.
  • It is particularly popular in silicone sealant and rubber formulations as it improves mechanical reinforcement and imparts pseudoplasticity/thixotropy.
  • Thickening of PAO (polyalpha-olefin) base oils used in cable gels.
download AEROSIL 150 technical datasheet 223 KB

Key points at a glance:

  • High surface area hydrophilic fumed silica.
  • Optimal dispersion results in the pronounced thickening of a wide range of liquids.
  • Excellent transparency in unsaturated polyester resins.
download AEROSIL 300 technical datasheet 653 KB

Key points at a glance:

  • Hydrophobic fumed silica surface-treated with polydimethylsiloxane (PDMS). Low surface area.
  • Highly efficient thickening agent in complex polar liquids such as epoxy, polyurethane and vinyl ester resins. Stabilises pigments and provides anti-sagging.
  • Exceptionally hydrophobic: used in protective coatings to enhance corrosion resistance and wherever a reduction in moisture sensitivity is required.
download AEROSIL R202 technical datasheet 790 KB

Key points at a glance:

  • Medium surface area hydrophobic fumed silica, after-treated with octylsilane. Based on AEROSIL® 200.
  • Effective anti-settling aid in coating systems to stabilise pigments. Enhances corrosion protection.
  • Efficient rheology modification in complex liquid systems e.g. 2k epoxy resins.
download AEROSIL R805 technical datasheet 257 KB

Key points at a glance:

  • Hydrophobic fumed silica, after-treated with hexamethyldisilazane. Medium-high surface area. Based on AEROSIL® 300.
  • Improves mechanical and optical properties of silicone rubber formulations.
  • Efficient thickening and stabilisation of complex liquid systems e.g. 2k PUR.
download AEROSIL R812S technical datasheet 257 KB

Key points at a glance:

  • Low-medium surface area hydrophobic fumed silica with DDS surface treatment (dimethyldichlorosilane). It has a certain amphiphilic character to it.
  • Used for building viscosity, stability and pseudoplasticity in a wide range of liquids. It can be used in greases, solvent based inks and water based coatings.
  • Popular in free flow and anti-caking applications.
download AEROSIL R972 technical datasheet 219 KB

Key points at a glance:

  • A mixture of AEROSIL® 200 and highly dispersed fumed aluminium oxide in a 5:1 ratio. Medium surface area.
  • One of the most potent thickeners for aqueous/highly polar systems.
  • Imparts shear-thinning behaviour and thixotropy.
download AEROSIL COK84 technical datasheet 257 KB