Hydrophobic Fumed Silica | Applications and Product Polarity

Hydrophobic fumed silica is prepared by modifying hydrophilic fumed silica by treating agents of HMDS(Hexamethyldisilazane), PDMS(Polydimethylsiloxane), DDS(Dimethyldichlorosilane), or special silane. (Why fumed silica need to be treated to be hydrophobic?)

  • Hydrophobic Nature: Repels water molecules; doesn’t mix or disperse in water, making it essential for water-resistant applications.
  • Rheology Control: Modulates flow properties of liquids; ensures ease of pouring, spreading, or application.
  • Thickening Agent: Increases viscosity in polar liquids, ensuring desired consistency and texture in formulations.
  • Reinforcing Agent: Adds strength and durability to elastomers, enhancing their performance and lifespan.
  • Improves Hydrophobicity: Enhances water resistance, making products less prone to water damage or degradation.
  • Corrosion Resistance: Offers a protective layer, preventing materials from corroding, especially when exposed to harsh environments.
  • Enhanced Dielectric Performance: Boosts electrical insulating properties, beneficial in electronic applications.
  • Improved Scratch Resistance: Provides a protective barrier, reducing the risk of surface scratches and enhancing product durability.

Hydrophobic fumed silica has low polarity, makes it suitable for products of medium or high polarity systems, medium polarity systems products including polyurethane, polyols, polyimide, etc, and high polarity system products such as epoxy resin, vinyl resin, amine substances, cyanoacrylate, isocyanate (e.g., MDI, TDI), and polar solvents (e.g., alcohols, ketones, acetates). Hydrophobic fumed silica is also suitable for some low polarity system products such as MS Polymer, STP-E, polyacrylic acid acetate, polysulfide, etc.

HIFULL Hydrophobic Fumed Silica
Hydrophobic fumed silica is a form of silicon dioxide (commonly known as silica) that has hydrophobic groups chemically bonded to the surface. It’s treated silica or structure-modified silica. HIFULL hydrophobic fumed silica is structure-modified silica after being treated by HMDS, PDMS, DDS.

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As the differences in the polarity of hydrophobic fumed silica, variations in compatibility with different chemical system products exist, Please check the below table based on their specific product polarities for usage:

Polarity LevelMaterials/ProductsRecommended Fumed Silica
Non-polarity ProductMethyl Organosilicon
PVC (Polyvinyl Chloride)
Aromatic/Aliphatic Hydrocarbons (e.g., Butyl, Styrene)
Non-polar Solvents (e.g., THF – Tetrahydrofuran)		HIFULL HL-380
HIFULL HL-300
HIFULL HL-200
HIFULL HL-150
Low-polarity ProductMS Polymer
STP-E
Polyacrylic Acid Acetate
Polysulfides		HIFULL HB-152
HIFULL HB-151
Medium-polarity ProductPolyurethane
Polyols
Polyamides		HIFULL HB-139
High-polarity ProductEpoxy Resins
Vinyl Resins
Amine Compounds
Cyanoacrylate
Isocyanates (e.g., MDI, TDI)
Polar Solvents (e.g., Alcohols, Ketones, Acetic Solutions)		HIFULL HB-139

Hydrophobic fumed silica possesses low hygroscopicity, excellent dispersibility, and the ability to regulate rheology in polar systems. Some HIFULL hydrophobic fumed silica with post-treatment and structure modification can further assist customers in developing new products and improving product performance.

Hello, Customers

My name is Van, I’m the business manager of HIFULL, I have been in Fumed Silica Industry for more than 10 years. Feel free to contact me. I’m happy to provide you the best service and products.
Van
Business Manager