Synthesis of ammonium persulfate microcapsule with a polyaniline shell and its controlled burst release

Abstract

Polymer hydraulic fracturing is important for increasing production during petroleum exploitation. After fracturing, the high-viscosity polymer should be completely decomposed by gel breakers (ammonium persulfate [APS]) to realize high conductivity in the proppant pack. A new series of polyaniline microcapsules loaded with APS for the preparation of delayed-release gel breakers were synthesized via in situ polymerization. The silica nanoparticles were doped in polyaniline to control the release of the encapsulated APS. The morphology, shell wall thickness, and elemental composition of the microcapsules were characterized by scanning electron microscopy, transmission electron microscopy, and two-dimensional scanned energy-dispersive X-ray spectroscopy. The results revealed that the microcapsules were irregularly spherical with average diameters of about 5-6 μm and had shell thicknesses of 150-300 nm, and the silica nanoparticles had been successfully doped in the polyaniline shell. The microcapsules had a burst release pattern, and their initial release time was precisely controlled by adjusting the concentration and temperature of the sodium hydroxide solution. With increased demands for high performance delayed-release microcapsules, the prepared polyaniline microcapsules loaded with APS show great potential for practical applications in petroleum exploitation, self-healing coating, fiber printing, and grease.

A Supramolecular Reinforced Gel Fracturing Fluid with Low Permeability Damage Applied in Deep Reservoir Hydraulic Fracturing

“…The higher the temperature, the faster the dissolution rate of the surface of the capsule. Therefore, the magnitude of the conductivity is controlled by temperature [41]. Capsule-B has a longer delay time than Capsule-A under the same amount of gel-breaker release.…”

“…Some tiny cracks appeared on the surface of Capsule-A when the temperature was 60 • C, as shown in Figure 6c, indicating that Capsule-A began to release the gel-breaker at 60 • C. When the temperature increased to 90 • C, there were more cracks on the surface of Capsule-A, as could be seen in Figure 6d, and the width of the cracks was wider, indicating that the release rate of the gel-breaker should be faster at 90 • C. The above conclusions were consistent with those obtained in Figure 5c. The experiment showed that the surface of Capsule-A would generate cracks after being soaked in high-temperature water and then releasing the gel-breaker [41]. It could be seen from the conductivity experiment that Capsule-A and Capsule-B both had the property of delaying the release of the gel-breaker, but the mode of the delaying release needed further research.…”

Effect of glycerol on electrical conducting of chitosan/polyaniline blends

“…This polymer has a wide range of application (light-emitting diodes, plastic batteries, switchable membranes, sensors, energy storage devices, anti-static and anti-corrosion coating materials), and has high environmental stability; low cost of the monomer (aniline); high yield easy synthesis; adsorbent properties; as well as modification of mechanical, electromagnetic and solubility properties due to doping acid. 8,9,[14][15][16][17][18] PANI has different oxidation states controlled by oxi-reduction processes, in which protonation and deprotonation occur due to the addition of acids and alkaline solutions. 12,19 Many recent works of Cs/PANI blends carried out the in-situ polymerization of PANI associated with chitosan generating a powder with the ability to adsorb materials such as dyes.…”

In‐situ polymerization of polyaniline in PDADMAC/PSS complex membranes: Effect of the polyelectrolyte stoichiometry

“…PANI is typically synthesized in a powder form and blended in the polymer matrix as a filler 5 . Aniline (ANI) can not only be in‐situ polymerized in membranes by solvent infusion of the active component but also around APS loaded capsule thus forming a shell of PANI allowing for the delayed slow release of the remaining APS 6 . Another very common approach used is the electro‐polymerization of ANI onto an electrode to produce PANI but it is restricted to electrically conducting substrates found for examples in solar cells or fibers through an interfacial polymerization approach 7,8 .…”

“…5 Aniline (ANI) can not only be in-situ polymerized in membranes by solvent infusion of the active component but also around APS loaded capsule thus forming a shell of PANI allowing for the delayed slow release of the remaining APS. 6 Another very common approach used is the electro-polymerization of ANI onto an electrode to produce PANI but it is restricted to electrically conducting substrates found for examples in solar cells or fibers through an interfacial polymerization approach. 7,8 Small molecular dopants such as hydrochloric, perchloric, sulfuric, methanesulfonic, benzenesulfonic, p-toluenesulfonic, and macromolecular dopants such as poly(styrene sulfonate (PSS)), poly(vinylsulfonic), poly(acrylic), and poly(anilinesulfonic) acids were used to study the redox properties of PANI.…”