Research on the dispersion technology and stability of silica is a core topic in the field of materials science.  Through various technical means such as high-shear dispersion, surface modification, and the application of dispersants, the problem of silica particle agglomeration can be effectively solved, significantly improving its application performance in fields such as rubber, plastics, and coatings.
I. Main Methods of Silica Dispersion Technology
1. High-Shear Dispersion Technology
High-shear dispersion technology is one of the most mainstream methods for silica dispersion.  It involves thoroughly mixing silica with the matrix using high-speed stirring equipment or high-shear dispersers to form a uniformly dispersed system. This method utilizes strong shear forces to effectively break down the agglomerated structure of silica, ensuring uniform dispersion of particles and improving dispersion efficiency and product quality stability. In practical applications, the dispersion effect can be further optimized by adjusting parameters such as stirring speed, time, and temperature.
2. Surface Modification Dispersion Technology
Surface modification technology, which improves dispersibility by changing the chemical properties of the silica surface or adding a surface covering layer, is an important emerging method in recent years. Commonly used surface modifiers include organosilicon compounds and polymers, which interact with silica particles to prevent agglomeration. For example, introducing hydrophobic groups to the silica surface or modifying it with silane coupling agents can significantly reduce the attractive forces between particles and enhance the dispersion effect.
3. Dispersant Application Technology
Dispersants are a key component in silica dispersion technology, mainly composed of surfactants, stabilizers, and auxiliary agents. Silica dispersants such as HST and ST form a stable adsorption layer on the particle surface, causing the particle surface to be charged or electrically charged, thereby generating electrostatic or electric double-layer repulsion, effectively preventing particles from re-aggregating. The selection of dispersants needs to consider the surface properties of silica and its application field, such as anionic surfactants being suitable for small particles or silica with a high specific surface area.
4. Physical and Chemical Dispersion Technologies
Physical and mechanical dispersion technologies include ultrasonic dispersion and mechanical shearing methods, which disperse silica particles in a solvent through external forces. Ultrasonic dispersion utilizes the mechanical vibration of ultrasound to disperse particles in a liquid, and is an efficient and rapid dispersion method. Chemical dispersion technology achieves the chemical dispersion of precipitated silica through the introduction of chemical substances such as surface treatment agents. Surfactants can chemically react with the surface of precipitated silica, strengthening its interaction with the matrix.

II. Key Factors Affecting the Dispersion Stability of Precipitated Silica
1. Surface Energy and Kinetic Equilibrium
The surface energy of precipitated silica is usually higher than that of most matrix materials, which hinders its compatibility and dispersibility with the matrix materials. In addition, the interparticle forces of precipitated silica are strong, making it prone to aggregation. Traditional dispersants often fail to effectively break down this aggregation, resulting in poor dispersion. The reactivation of high-energy surfaces is also a challenge; the surface of precipitated silica is modified through high-temperature calcination and other treatment methods, placing it in a high-energy state, making it more susceptible to aggregation.
2. pH Value and Electrolyte Concentration
pH value is an important factor affecting the precipitation of precipitated silica. A lower pH value makes the surface charge of precipitated silica more positive, increasing the interparticle forces and promoting precipitation. High concentrations of electrolytes increase the ion concentration in the solution, affecting the stability of precipitated silica colloidal particles. When the electrolyte concentration is high, the electrostatic force between the electrolyte and the precipitated silica exceeds the dispersion force, leading to the formation of precipitates.
3. Temperature and Solvent Properties
Heating and concentrating the solution changes the physical properties of water, reducing the dispersibility of precipitated silica in the solution and leading to its precipitation. The polarity and viscosity of the solvent also affect the dispersibility of precipitated silica. The ion concentration in the solvent and the interaction force between the solvent and the precipitated silica particles are important factors affecting dispersibility.

III. Strategies to Improve the Dispersion Stability of Precipitated Silica
1. Surface Modification and Dispersant Optimization
Surface modification can regulate the hydrophilicity and hydrophobicity of precipitated silica, thereby affecting its dispersibility. The addition of coating agents or surface treatment agents can effectively improve the dispersibility of precipitated silica. Choosing appropriate dispersants and adding them to the system at the recommended dosage can effectively improve the dispersibility of precipitated silica. Studies have shown that the addition of dispersants such as polyethylene glycol and sodium polyacrylate can reduce the D50 of precipitated silica particles from 25.2 μm to 11 μm. 2. Optimization of Process Parameters
Appropriate process parameters such as temperature, stirring speed, and stirring time are crucial for improving the dispersibility of precipitated silica. By optimizing these parameters, the aggregation of precipitated silica can be effectively reduced. For example, under conditions of a grinding time of 1.5 hours, a ball-to-material ratio of 5:1, a slurry mass fraction of 10%, and a dispersant dosage of 6%, the precipitated silica particles can be effectively deagglomerated and dispersed.
3. Application of Composite Technology
The composite method combines physical and chemical methods, achieving better dispersion and stability through the comprehensive application of multiple methods. For example, combining the oxidation method with the polymer dispersion method, by combining hydrophilic precipitated silica with a suitable polymer, a polymer-modified nanocomposite material is formed to improve the dispersion effect.