Abstract: The polymerization behavior of acrylamide at its low concentration in sodium silicate solution under different pressure of carbon dioxide was studied. The microstructure and rheological properties of the synthetic products were characterized by environmental scanning electron microscope(ESEM), rheometer and laser particle sizer. A mixture is produced in experiments and will have larger storage modulus or viscoelasticity at a higher CO₂ concentration. It has a complex network structure formed by silicic acid gel embedded into polyacrylamide gel. After detaching from the mixture when exposed to ultrasonic wave, the silicate granules have a particle size distribution range of 280—900 nm, and their average size becomes smaller with the increase of exposure time. The mechanisms is that carbon dioxide helps increase both the diffusion velocity of AM molecule and also contact chance among the AM and initiator and crosslinking agent, which could enhance the molecule weight of the products.

Key words: Carbon dioxide, Geological sequestration, Acrylamide, Sodium silicate, Composite gel