860. Covalent Modification of Surfaces with Anionic Polymers Controls Release and Enhances Transfection of DNA/Cationic Polymer Complexes

The main characteristics of aggregates formed during the flocculation of clay-salt slurry using polyacrylamide-based polymers with various types of charge and molecular weights were studied using a laser analyzer of particle size Lasentec D600L of the FBRM system. The effect of the polymer type on the size of the floccules formed and their density was shown. It has been established that when using non-ionic polyacrylamide and its anionic copolymers floccules with a size of 500-600 mm are formed, and when flocculated with a cationic reagent, the floccules do not exceed 300 mm It was shown that an increase in the molecular weight of the cationic polymer does not contribute to an increase in the size of the aggregates of the clay slurry particles. It has been proven that with the use of non-ionic polyacrylamide and its anionic copolymers, the density of floccules significantly decreases with increasing their size, which is an important property of fractal aggregates. If the charge density of anionic polymers increases, the aggregates density decreases, due to electrostatic repulsion between the negatively charged polymer and the negatively charged surface of the sludge. Analysis of the kinetics of the clay sludge flocculation process showed that when using non-ionic and anionic polymers, fast flocculation occurs, and the number of primary particles in the aggregate does not exceed several units. When using a cationic polymer, the filling of the intraflouclear volume with primary particles occurs due to the displacement of the liquid phase, which contributes to the formation of dense and compact floccules. The results obtained can be used for the selection of flocculant in order to improve the process of thickening clay-salt sludge in the production of potash fertilizers.

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A New Cationic Polymer System That Improves Acid Diversion in Heterogeneous Carbonate Reservoirs

SPE Journal ◽

10.2118/194647-pa ◽

2020 ◽

Vol 25 (05) ◽

pp. 2281-2295

Author(s):

Abhishek Sarmah ◽

Ahmed Farid Ibrahim ◽

Hisham Nasr-El-Din ◽

Jennifer Jackson

Keyword(s):

Rheological Properties ◽

Experimental Studies ◽

Polymer System ◽

Cationic Polymer ◽

Carbonate Reservoirs ◽

Acid System ◽

Anionic Polymers ◽

The Matrix ◽

Acid Diversion ◽

Indiana Limestone

Summary In-situ gelled acids are used for acid diversion in heterogeneous carbonate reservoirs. However, most of the gelled systems are based on anionic polymers that are difficult to clean up after the acid treatments. Residual polymer deposition leads to formation damage by blocking pore throats in the matrix. This work evaluates a new cationic-polymer acid system with self-breaking ability for application as an acid diverter in carbonate reservoirs. Experimental studies have been conducted to examine the rheological properties of these polymer-based acid systems. The apparent viscosities of the live and the partially neutralized acids at pH from 0 to 5 were measured against the shear rate (0 to 1000 s−1). The effects of salinity and temperature (80 to 250°F) on the rheological properties of the acid system were also studied. The viscoelastic properties of the gelled acid system were evaluated using an oscillatory rheometer. Dynamic sweep tests were used to determine the elastic (G′) and viscous (G″) moduli of the system. Single-coreflood experiments were conducted on Indiana limestone cores to study the nature of diversion caused by the polymer-acid system. The effect of permeability contrast on the process of diversion was investigated by conducting dual-coreflood experiments on Indiana limestone cores that had permeability contrasts of 1.5 to 20. Computed tomography (CT) scans were conducted to study wormhole propagation after acid injection for both single and dual cores. The live acid system displayed a non-Newtonian shear-thinning behavior with the viscosity declining as temperature increased. For 5 wt% hydrochloric acid (HCl) and 20 gal/t polymer content at 10 s−1, the viscosity decreased from 230 to 40 cp as the temperature increased from 88 to 250°F. Acid-spending tests demonstrated that the acid generated a gel with improved viscosity of 260 cp (at 250°F and 10 s−1) after it reached a pH of 2. The highly viscous gel plugged the wormhole and forced the acid that followed to the next higher-permeability zone. The viscosity of the gel continued to increase until it broke down to 69 cp (at 250°F and 10 s−1) at a pH of 4.8, which indicates a self-breaking system and more thorough cleanup potential. Coreflood studies indicated that the wormhole and the diversion process are dependent on the temperature and the flow rate. There was no indication of any damage caused by the system. The injected acid pore volume to breakthrough (PVBT) decreased from 2.2 to 1.4 when the temperature increased from 150 to 250°F. The strong elastic nature of the gel (G′ = 3.976 Pa at 1 Hz) formed by the partially neutralized acid system proves its suitability as a candidate for use as a diverting agent. This new acid-polymer system has significant promise for use in acid diversion to improve stimulation of carbonate reservoirs.

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Zinc improves gene transfer mediated by DNA/cationic polymer complexes

The Journal of Gene Medicine ◽

10.1002/jgm.303 ◽

2002 ◽

Vol 4 (5) ◽

pp. 548-559 ◽

Cited By ~ 34

Author(s):

Chantal Pichon ◽

Brigitte Guérin ◽

Matthieu Réfrégiers ◽

Christine Gonçalves ◽

Paul Vigny ◽

...

Keyword(s):

Gene Transfer ◽

Cationic Polymer ◽

Polymer Complexes

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Synthesis of calcium silicate hydrate/polymer complexes: Part I. Anionic and nonionic polymers

Journal of Materials Research ◽

10.1557/jmr.1999.0458 ◽

1999 ◽

Vol 14 (8) ◽

pp. 3379-3388 ◽

Cited By ~ 49

Author(s):

Hiroyoshi Matsuyama ◽

J. Francis Young

Keyword(s):

Nuclear Magnetic Resonance ◽

Magnetic Resonance ◽

Calcium Silicate ◽

Calcium Silicate Hydrate ◽

Magic Angle Spinning ◽

Magic Angle ◽

Polymer Complexes ◽

Anionic Polymers ◽

Angle Spinning ◽

Nuclear Magnetic

High molecular weight anionic polymers have been incorporated into the calcium silicate hydrate (C–S–H) structure during precipitation of quasicrystalline C–S–H from aqueous solution. The anionic polymers studied were poly(methacrylic acid), poly(acrylic acid), and the sodium salt of poly(vinyl sulfonic acid). Expansion of the interlayer spacing coupled with high-carbon contents confirmed that the polymers intercalated between the layers. D-gluconic acid behaves similarly. Intercalation characteristics strongly depended on both the type of polymer and Ca/Si molar ratio of C–S–H; intercalation reached a maximum at an initial Ca/Si = 1.3 in all cases. Poly(vinyl alcohol) was the only nonionic polymer among those studied that was incorporated into C–S–H. Evidence for interlayer intercalation is less definite. The C–S–H/polymer complexes were examined by Fourier transform infrared spectroscopy, 29Si nuclear magnetic resonance magic angle spinning, and 13C cross-polarization, magic angle spinning nuclear magnetic resonance spectroscopy.

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