As a revolutionary two-dimensional nanomaterial, graphene possesses vast application prospects in composite materials, energy storage, and electronic devices due to its ultra-high specific surface area, excellent electrical and thermal conductivity, and mechanical properties. However, the strong van der Waals forces and π-π conjugation between graphene sheets make them prone to agglomeration and stacking, leading to a significant decrease in effective specific surface area and hindering the realization of its superior performance. Therefore, graphene dispersion technology has become a core key to unlocking its application potential.
The essence of graphene agglomeration is the spontaneous regulation of its thermodynamically unstable state. High surface energy drives the sheets to reduce energy through aggregation, while hydrogen bonding, electrostatic interactions, and factors such as ambient temperature and solvent properties further exacerbate agglomeration. Studies have found that the performance of undispersed graphene agglomerates is even inferior to that of ordinary graphite materials, making dispersion technology the first hurdle in the industrialization of graphene.
Currently, the mainstream graphene dispersion methods can be divided into two main categories: physical dispersion and chemical modification. Physical dispersion methods, due to their advantage of not damaging the intrinsic structure of graphene, have become a common technique in both laboratory and industrial fields. Among them, ultrasonic dispersion utilizes the localized high temperature and pressure generated by cavitation effects and shock waves to effectively overcome interlayer forces and achieve exfoliation. By optimizing power and time, high-concentration, stable dispersions can be prepared. Mechanical shearing methods apply external forces for dispersion through ball milling, high-speed stirring, etc. The equipment is simple and easily scalable, but precise control of the intensity is required to avoid sheet damage. Emerging technologies such as microwave radiation and pulsed magnetic fields improve structural integrity while ensuring dispersion effectiveness through non-contact action.
Chemical modification methods fundamentally improve dispersion stability by introducing functional groups such as hydroxyl and carboxyl groups onto the graphene surface or adding dispersants to create steric hindrance. Graphene oxide prepared by redox methods, due to its rich surface oxygen-containing functional groups, can be stably dispersed in aqueous phases, and its intrinsic properties can be partially restored after reduction. Appropriate selection of nonionic or anionic dispersants can form a protective barrier through adsorption, significantly inhibiting agglomeration, making it particularly suitable for practical applications such as composite material preparation.
A high-quality graphene dispersion system is fundamental to its performance. Dispersion effectiveness can be accurately evaluated through characterization techniques such as dynamic light scattering, zeta potential measurement, and electron microscopy. In the future, dispersion technology will develop towards intelligence and refinement, achieving a balance between dispersion efficiency, product quality, and cost-effectiveness through synergistic optimization of physical and chemical methods. This will propel graphene from the laboratory to large-scale industrial applications, injecting core momentum into the innovation of the new materials industry.
