Polyacrylamide and its derivatives for oil recovery

 
Combined Modified Polyacrylamides and Hybrid Polyacrylamides 
Hydrophobically associating polyampholyte successfully introduces the combined 
effects of electrostatic attraction between opposite charges and hydrophobically 
associating interactions between intra-and/or intermolecular chains in a single co-
polyacrylamide. Concurrently, the two different effects can exert influence towards each 
other, which contributes special polymer solution properties.[155]
An, et al.[156] synthesized one form of HAPA under free radical micellar 
polymerization using the monomers AM, AA, and dimethyldodecyl(2-
acrylamidoethyl)ammonium bromide (AMQC12). They first prepared the ionic surfmer, 
i.e., surfactant monomer AMQC12, from N,N-dimethylethylenediamine, methylene 
chloride and dodecyl-1-bromide. Copolymerization of the surfmer alkene with AM and 
AA generated the targeted polymer material. The solution viscosity of the HAPA 
polymer increased with addition of NaCl due to an anti-associative, polyelectrolyte 
effect. 
Zhong, et al.[27] polymerized terpolymers (PADB) with AM as the main 
monomer, 4-butylstyene (BST) and dimethyldiallyl ammonium chloride (DMDAC) as 
the hydrophobic monomers, by the micellar free radical copolymerization technique. 
When the polymer concentration was increased above the critical association 
concentration (CMC), the viscosity of PADB was dramatically improved. The polymer 
provided an effective viscosification effect in 2.222 mol∙L
-1 
NaCl solution, exhibiting 
good salt resistance. Large hydrophobic aggregates were formed in aqueous 0.1g dL
-1
PADB where the hydrophobic structure became further enlarged when enhancing the 
concentration. These microstructures were disrupted by adding small amounts of salt, 

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resulting in decreased solution viscosities. However, with further increases of NaCl 
concentration, aggregates were again increased and formed dendritic, associating 
structures, leading to enhanced solution viscosity. 
Organic-inorganic hybrid composites are an emerging class of materials holding 
significant promise because usually they have the combined/synergistic properties.[157, 
158] While in polyacrylamides, the functional groups, such as -NH
2
, -COOH, can form 
Van der Waals force, hydrogen bonding, electrostatic interaction and ionic force with 
inorganic particles and clay.[159, 160] For clay incorporation, few polymer chains can 
penetrate the clay’s interlayer space and then entangle to each other therefore to form a 
kind of reinforcement (weak)[161], see Figure 6. While obvious viscosity increment is 
brought by a kind of extra gallery viscous force (similar to friction force)[162] (dominate 
reason for viscosity increasing). For nanoparticle incorporation, similar force occur due 
to large surface area (see Figure 7). There have been a lot of attempts to import the 
inorganic materials to polyacrylamides system[163, 164].