Polyacrylamide and its derivatives for oil recovery

Fig. 7. 
Thermogravimetric (TG) curves of the hydrophobically modified copolymer.
 
Figure 8 displays the relation curves of the apparent viscosity of the HMPAM 
with different hydrophobe. For HPAM, the viscosity was increased steadily, while, at 
concentration around 1500 mg/L, an abrupt change occurred on HMPAM. This is the 
critical association concentration (
C*
) at which not only intermolecular association but 
also intramolecular association happening. At the same concentration, higher viscosity 
was observed for the copolymer with more hydrophobe, indicating association is 

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strengthened by increasing the hydrophobically dynamic crosslinking points created by 
the hydrophobes along HMPAM chain. 
Fig. 8. 
Apparent viscosity of aqueous solution as a function of copolymer concentration. 
Temperature: 30±0.5 °C, shear rate: 6 S
-1
.
 
4.
 
Conclusions
Polyacrylamide and poly (acrylamide-co-alkylacrylamide) had been syntheized 
by a water-free solvent in oil suspension polymerization. Alkylacrylamides were used as 
sufmer which can stabilize the suspension system as a surfactant and also polymerized 
into copolymer to introduce hydrophobic domain. Compared to hydrophobically 
modified polyacrylamides prepared by traditional methods, higher mol.-% hydrophobe 
could be incorporated into copolymer and more than this number could be achieved by 
virtue of this water-free suspension polymerization with alkylacrylamides as 

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polymerizable surfactants. Indeed, the solubility of the obtained products are not good as 
other hydrophobic modified polyacrylamide prepared by other polymerization with water 
as the solvent for monomers. This method has potential to be used in preparing swell-
delayed polyacrylamides or microgels which could be used in oil recovery.

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