Polyacrylamide and its derivatives for oil recovery

Fig. 3. 
Schematic representation of the copolymerization mechanism in the water-free 
S/O system: hollow black circle, water-soluble monomer, AM; red circles with an 
attached line; solid black circle: free radical.
 

---

125 
Micellar polymerization is the most common method in synthesizing HAPAM. 
The ‘microblocky’ segmental structure has been postulated for a number of years.[40-43] 
In micellar polymerization, the hydrophobic monomer is solubilized within surfactant 
micellar, whereas acrylamide monomer is dissolved within continuous aqueous medium. 
At beginning, AM is initiated by water soluble initiator and started polymerization.
Polymer chains propagate mainly in aqueous phase. When a growing radical moves into 
micellar, the solubilized hydrophobic monomers are polymerized immediately. This 
polymerization is conducted in a local hydrophobe rich micelle, resulting in a 
hydrophobic blocky structure in the copolymer chain[44]. However, it is unclear about 
the micro structure of the poly-(acrylamide-
co
-alylacrylamide) prepared by water-free 
suspension system. Supposedly the molten acrylamide monomer liquid was dispersed 
within a non-polar solvent to form a suspension with the assistance of surfactant. Then 
the oil soluble initiator creates the free radical in continuous oil phase. When the free 
radical moves into the micelle, chain propagates immediately and both the acrylamide
Fig. 4.
The SEM picture of crude poly-(acrylamide-co-octadecylacrylamide). 

---

126 
monomer as well as the hydrophobic monomers within micelle will be polymerized into 
polymer chain. Figure 4 shows the SEM picture of the crude product. The spherical 
particles were achieved after polymerization conformed to our proposed mechanism. 
Water-free S/O suspension polymerizations of acrylamide and poly (acrylamide-
co-octadecylacrylamide)s were carried out isothermally over the temperature of 85 °C. 
For the synthesis of polyacrylamide, surfactant Span 85 was used as surfactant, with 1.5 
wt-% of mineral oil. For the hydrophobically modified copolymer, octadecylacrylamide 
was used as surfactant and hydrophobic monomer with designed amount. The specific 
experimental conditions for each polymerization are listed in Table 2.