Rheological properties and enhanced oil recovery performance of a novel sulfonate polyacrylamide

An Exceptionally Salt Tolerant Copoly(Maleimide Sulfobetaine) - Structural Requirements for Ultra-Salt Tolerance

Zwitterionic polymers are an important class of polymers with far-ranging applications. In the widely studied poly(meth)acrylate and poly(meth) acrylamide-based zwitterions, properties can be tuned by changing the nature of substituents attached to ammonium ions. However, these changes influenced salt tolerance of zwitterionic polymers only to a limited extent. Upon adding salt these polymers expanded in solution initially. Further increase in salt concentration caused the polymer chains to shrink similar to the common water soluble, uncharged polymers thereby deteriorating the viscosity of aqueous solutions. In contrast to the conventional poly(meth)acrylate and poly(meth)acrylamide-based zwitterions, zwitterionic copolymaleimides showed substituent dependent salt-tolerant nature. In the absence of any substituent on the polymer backbone such as zwitterionic poly(ethylene-alt-maleimide) (ZI-PEMA) the viscosity of salt solutions increased both with the increasing salt concentration as well as the concentration of polymer. This is likely due to the continuous expansion of polymer coil in salt solutions with increasing salt concentration caused primarily by the rigidity of the polymer backbone. ZI-PEMA also enhanced the saturation limit of mono- and divalent salts like sodium chloride and hydrated calcium bromide in water. This property is useful for various applications like fish curing, for making high-density fluids, refrigeration, etc. across various industrial sectors.

Salt-Induced Coil-Globule Transition of Sulfonate-Modified HPAM is Affected by the Branched Chain Length

Polymer flooding is a cheap and efficient method for tertiary oil recovery. However, the failure of partially hydrolyzed polyacrylamide (HPAM) molecules reduces the oil displacement efficiency under high salinity conditions. In this study, we modified HPAM molecules by sulfonic acid groups with different branched chain lengths, and we characterized the structures of these molecules in different salinity solutions through all-atoms molecular dynamics simulation. Compared with the acrylic group, the sulfonate group has excellent salt resistance because of its weak ability to attract cations. When using different lengths of branched linked branch sulfonates, increasing the length of the branched chain can improve the movement ability of sulfonates, so as to play a better salt resistance effect. However, excessive growth of branched chains can cause their association with each other and can lead to polymer folding. Therefore, we believe that the branched chain length of sulfonate should be moderately increased. These results are expected to provide theoretical support for the design and use of salt-resistant polymers..

Preparation of amphiphilic copolymers via base-catalyzed hydrolysis of quaternized poly[2-(dimethylamino)ethyl methacrylate]

The multi-stimuli-responsiveness of tertiary amine-containing polyacrylates makes them highly attractive for use in a wide range of applications. In the last decade, poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) has received exceptionally large attention...

Rheological and thermal stability of interpenetrating polymer network hydrogel based on polyacrylamide/hydroxypropyl guar reinforced with graphene oxide for application in oil recovery

The purpose of the present work is to enhance the thermal stability and rheological properties of semi-interpenetrating polymer network (IPN) hydrogel based on partially hydrolyzed polyacrylamide/hydroxypropyl guar (HPAM/HPG) nanocomposite reinforced with graphene oxide (GO), at temperatures (200 and 240 °F) for use in oil recovery applications. FTIR spectra of the IPN nanocomposite hydrogels revealed interactions of GO with HPAM/HPG chains. An increase in the viscosity is also observed from the rheological study. Moreover, IPN and its nanocomposite hydrogels exhibited non-Newtonian behavior. The decline of viscosity of IPN nanocomposite hydrogels was observed with an increase in the temperature from 200 to 240 °F but was still higher than IPN hydrogel without GO. Dispersion of GO through the HPAM/HPG hydrogel matrix was evaluated by SEM morphology and electrical conductivity. The IPN nanocomposite hydrogels showed high viscosity stability, thermal stability, and flow activation energy as compared to IPN hydrogel without GO. Therefore, the addition of 0.1 wt.% of GO to the HPAM/HPG matrix is suitable to create a cross-linked polymer solution with improved properties which may be beneficial for use in oil recovery applications.

Direct synthesis via RAFT of amphiphilic diblock polyelectrolytes facilitated by the use of a polymerizable ionic liquid as a monomer

A novel method to prepare amphiphilic block polyelectrolytes with a strongly hydrophobic block under homogeneous conditions is presented here.