In the field of nanomaterials applications, silica nanoparticles are widely used in coatings, composite materials, biomedicine, and other industries due to their high specific surface area, excellent chemical stability, and optical properties. However, due to their high surface energy, nanoparticles are prone to aggregation, a problem that severely restricts their performance and application expansion. Against this backdrop, ultrasonic dispersion technology, with its advantages of high efficiency, environmental friendliness, and ease of operation, has become a key means to solve the aggregation problem of silica nanoparticles.
The core principle of ultrasonic dispersion technology is the "cavitation effect" generated when ultrasound propagates in a liquid medium. When ultrasound acts on a suspension containing silica nanoparticles, a large number of tiny bubbles are continuously generated inside the liquid. These bubbles expand rapidly during the negative pressure phase of the sound wave and burst instantaneously during the positive pressure phase. The bursting of these bubbles releases enormous energy, creating a localized high-temperature, high-pressure environment and generating strong microjets and shock waves. This physical action effectively breaks down the van der Waals forces and hydrogen bonds between silica nanoparticles, dispersing agglomerates into single or small particles while preventing re-agglomeration, ultimately achieving uniform dispersion.
Compared to traditional mechanical stirring and high-speed shearing methods, ultrasonic dispersion technology offers significant advantages. Firstly, it boasts higher dispersion efficiency, achieving ideal dispersion results in a shorter time, with better dispersion uniformity, effectively reducing the particle size distribution range. Secondly, this technology eliminates the need for large amounts of dispersants, minimizing interference from chemical reagents in subsequent application systems, aligning with the green and environmentally friendly industrial development requirements. Furthermore, the ultrasonic dispersion process requires relatively simple equipment, facilitating continuous production and making it suitable for industrial applications of varying scales.
In practical operation, several key parameters must be carefully controlled to ensure optimal dispersion results. Firstly, the ultrasonic power is crucial. Too low a power may fail to completely break up the agglomerates, while too high a power can cause a rapid increase in liquid temperature, affecting the stability of the silica nanoparticles. Secondly, the ultrasonic time needs to be adjusted based on the suspension concentration and the initial agglomeration state of the particles, typically ranging from a few minutes to tens of minutes. Furthermore, the pH value, solid content, and type of medium of the suspension also affect the dispersion effect. For example, silica nanoparticles exhibit better dispersion stability in neutral or weakly alkaline media.
Currently, ultrasonic dispersion technology for silica nanoparticles has been industrialized in multiple fields. In the coatings industry, dispersed nano-silica can be used as a modifier, significantly improving the wear resistance, aging resistance, and optical transparency of coatings. In the composite materials field, uniformly dispersed nanoparticles can form a good interfacial bond with the matrix material, greatly enhancing the mechanical properties of the composite material. In the biomedical field, this technology can be used to prepare nano-drug carriers, improving drug solubility and bioavailability. With continuous innovation and optimization of ultrasonic technology, its application in the dispersion of silica nanoparticles will become more widespread in the future, injecting new impetus into the development of the nanomaterials industry.
