Polyacrylamide and its derivatives for oil recovery

3.
 
Results and discussion 
3.1. Synthesis and Mechanism 
Polyacrylamides were synthesized following the steps described in experimental 
part. Over twenty non-ionic surfactants had been studied in stabilizing our S/O 
suspension. Furthermore the surfmer was employed to stable the S/O suspension, and 
also participated into the polymerization to make HAPAM. 
3.1.1.
 
 Effect of reaction flask polarity 
In this reaction, the neat inner surface of the glass reaction flask could introduce 
polymer particle aggregation and adhesion on the reactor wall. Wall adsorption was 
controlled when inner surface of the reaction flask was modified by a long aliphatic chain 
coating. 

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3.1.2.
 
 Effect of surfactants on stability of system 
The suspension polymerization of acrylamide was studied in a water-free system. 
AM was dispersed in non-polar solvent, mineral oil, in a molten liquid state. With the 
assistance of proper surfactants and high shearing, the small droplets of the AM liquid 
were dispersed in a comparable stable state and formed a kind of solvent in solvent 
suspension. A number of surfactants were studied to stabilize the water-free S/O system, 
to minimize the consumption of surfactant and to maximize the feed of monomer amount. 
Over twenty non-ionic surfactants with different hydrophilic-lipophilic balance (HLB) 
had been investigated in stabilizing this water-free suspension system. Surfactants which 
can give stable milky suspension and particle products after polymerization were 
considered effective ones for this S/S suspension system, see Table 1, marked as stable 
(S). For unstable suspension systems, the added surfactants could not emulsify the system 
effectively to give phase-separated layers even after high speed shearing, marked as 
unstable (U). Generally, surfactants with low HLB values (<7) stabilize water-in-oil 
(W/O) suspension s/micellar (W/O surfactants), while surfactants with high HLB values 
(>7) stabilise oil-in-water (O/W) suspension /micellar (O/W surfactants).[33, 34] From 
the experiment results, surfactants with low HLB worked better than the surfactants with 
high HLB for this S/O suspension system. The reason is surfactants with low HLB have a 
structure of small polar (hydrophilic) head and long non-polar (hydrophobic) tail, which 
enables their small head go into polar liquid monomer droplets while their long tail 
extend in outside non-polar hydrophobic medium to stabilize the polar droplets in our 
S/O system. 

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