In industrial practice, polyacrylamide and its derivatives are primarily synthesized via free radical polymerization. Based on the dispersion state, the polymerization methods can be categorized as follows:
(1) Aqueous Solution Polymerization
Aqueous solution polymerization is the most widely used method for producing polyacrylamide. Water-soluble monomers are dissolved in deionized water, followed by oxygen removal using nitrogen gas. A suitable initiator is then introduced to initiate polymerization within an appropriate temperature range. This method offers advantages such as low cost, simple processing, and no need for solvent recovery, making it highly applicable in industrial production. Currently, the industrial manufacture of polyacrylamide-based flocculants predominantly relies on aqueous solution polymerization due to its operational simplicity and low technical barriers. Although the resulting polymer exhibits extremely high viscosity and cannot be used directly, it is often dried into powder form for convenient transportation.
(2) Suspension Polymerization
Suspension polymerization involves dispersing an aqueous solution of monomers and initiators as fine droplets in an organic solvent using dispersing or suspending agents. Key factors include the type and dosage of the dispersant. This method is characterized by low system viscosity, efficient heat dissipation, and relatively stable molecular weight and distribution of the product. However, the difficulty in completely removing the dispersant may adversely affect the polymer’s properties.
(3) Inverse Emulsion Polymerization
Inverse emulsion polymerization has become a research focus in emulsion polymerization studies worldwide. This technique employs a non-polar solvent as the continuous phase, while water-soluble monomers are dissolved in water as the dispersed phase. With the aid of an emulsifier, the aqueous phase is dispersed in the continuous phase to form a water-in-oil (W/O) inverse emulsion, which is then initiated by a free radical initiator. This system is complex and involves unique polymerization mechanisms, leading to the development of various methods such as inverse emulsion polymerization, inverse microemulsion polymerization, and saponification polymerization. However, inverse emulsion polymerization products are thermodynamically unstable and prone to phase separation during long-term storage.
Considering the current state of industrial production, adopting the aqueous solution polymerization route for synthesizing all copolymers discussed in this study represents an economically efficient and practical approach.
Post time: Nov-03-2025