Inverse Emulsion Polymerization Research Articles

Preparation, and characterization of different acrylamide-based polymers by inverse emulsion polymerization for water treatment

Preparation, and characterization of different acrylamide-based polymers by inverse emulsion polymerization for water treatment

High-Performance Nanogel-in-Oils as Emulsion Evolution Controller for Displacement Enhancement in Porous Media.

We designed and synthesized high-performance nanogel-in-oils with intermediate properties between solid particles and liquid droplets for multiphase flow control in porous media. The ultrasmall polymeric nanogels prepared via inverse emulsion polymerization were efficiently encapsulated in micrometer-sized oil droplets with the aid of surfactants during transfer from the oil phase to the aqueous phase. The composite colloidal system exhibited high loading capacity, unimodal size distribution, and long-term kinetic stability in suspension. The colloidal behaviors of nanogel-in-oils and the corresponding interfacial evolution during displacement in porous media were investigated via microfluidic experiments. In situ emulsification was observed with a state contrary to that of static characterizations. The spontaneous and sustainable formation of foam-like water-in-oil macroemulsions originated from aqueous phase breakup and oil film development, both enhanced by nanogel-in-oils. Sweeping efficiency enhancement by invasion events and residual oil transport in macroemulsion phases yielded exceptional displacement performances. Flow field fluctuations and emulsion state variations can be manipulated by adjusting nanogel-in-oil concentrations. The nanogel-in-oil suspension was found to exhibit optimal performance among the tested dispersed systems.

Preparation of nano-micron copolymers for polymer flooding using aqueous solution polymerization and inverse emulsion polymerization and their comparison

Oil displacing agents used in oil drilling and extraction can improve crude oil recovery. Acrylamide polymers were the most common oil displacing agents because of their high viscosity and low cost. However, conventional acrylamide polymers were susceptible to hydrolysis and thermal degradation in harsh reservoir conditions. Unique physical and chemical properties of nanoparticles promise to improve the performance of acrylamide polymers in harsh reservoir conditions. In this paper, the nano-micron copolymers of acrylamide (AM), 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS), and modified nano-silica (M-SiO2) were synthesized by two methods: aqueous solution polymerization and inverse emulsion polymerization, named W-PAAGS and E-PAAGS, respectively. The characterization was studied by Fourier transform infrared spectroscopy (FTIR), thermogravimetry (TG), particle size analysis, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The thickening ability, temperature resistance, salt resistance, and thermal stability of the two polymers synthesized were studied. The results showed that E-PAAGS had a better thickening ability than W-PAAGS. The viscosity of the E-PAAGS solution was much higher than that of the W-PAAGS solution at polymer concentrations above 5000 mg/L. The temperature and salt resistance of E-PAAGS was also better than that of the W-PAAGS. In addition, E-PAAGS exhibits better aging stability. After 30 days of aging, E-PAAGS had 71.3% viscosity retention whereas only 52.7% retention was observed for W-PAAGS, and the viscosity of E-PAAGS was always higher than that of W-PAAGS. The significant difference properties of W-PAAGS and E-PAAGS was due to the differences in copolymer structure caused by the different polymerization methods.

PH-Switchable W/O Polymer Emulsion: A Promising Strategy for Rapid Dissolution of Drag Reducers.

Additional hydrophilic surfactants are generally introduced into W/O emulsion drag reducer systems to enhance the dissolution capacity of polymers. The hydrophilic surfactants may decrease the stability of W/O emulsion, which leads to deterioration of polymer emulsions in the storage and transport process instead. Herein, a pH-switchable surfactant, N-(2-morpholinoethyl) oleamide (NMEO) was designed for stabilizing a W/O emulsion drag reducer. The surface activity and solubility changes occurring at pH < 6 of NMEO guaranteed the phase inversion from W/O to O/W of emulsions upon pH stimulation. Based on optimal conditions (oil-water ratio of 0.429, NMEO concentration of 3 wt%, and pH of 6.5), the inverse emulsion polymerization of poly(acrylamide-co-acrylic acid-co-2-acrylamide-2-methylpropane sulfonic acid) was proceeded to obtain a W/O polymer emulsion with the pH-switchable behavior. It was demonstrated that the polymer emulsions were provided with prolonged storage stability by NMEO and could be stored for at least 30 days due to the absence of hydrophilic surfactants. The polymers were released and completely dissolved within 2.5 min by pH stimulation, compared with traditional emulsion polymers and powder polymers that require 4 and 17 min, respectively. In addition, the emulsion drag reducer prepared by NMEO provided drag-reduction performance of 64.67% at 0.021 wt% concentration. The pH-switchable behavior of NMEO promotes the validity of W/O polymer emulsions along with the capacity of rapid release and solubilization, which eliminates the imbalance between the long-term storage stability and rapid solubility of traditional drag reducers. Thus, NMEO-stabilized emulsion drag reducers are expected to be a promising alternative for traditional products.

Amphoteric nano‐ and microgels with acrylamide backbone for potential application in oil recovery

AbstractAmphoteric nano‐ and microgels based on acrylamide (AAm), 3‐acrylamidopropyltrimethylammonium chloride (APTAC) and 2‐acrylamido‐2‐propanesulfonate sodium salt (AMPS) were prepared via inverse emulsion polymerization in the presence of crosslinking agent—N,N′‐methylenebisacrylamide (MBAA). Several polyampholyte nano‐ and microgel samples AAm‐APTAC‐AMPS with compositions (70:15:15, 80:10:10, and 90:5:5 mol%) were obtained and they were abbreviated as AAm70‐APTAC15‐AMPS15, AAm80‐APTAC10‐AMPS10 AAm90‐APTAC5‐AMPS5 (where the lower indexes indicate the molar concentration of monomers). The nano‐ and microgels were characterized by Fourier‐transform infrared spectroscopy, dynamic light scattering (DLS), transmission electron microscope (TEM), thermogravimetric analysis and interfacial tension measurements. The most attention was paid to the AAm80‐APTAC10‐AMPS10 microgel because its linear analog showed the best swelling capacity and the viscosifying effect for potential application in oil recovery. The influence of monomer concentration, surfactants, volume ratio of the water/organic phases, and the hydrophilic–lyophilic balance (HLB) on the average hydrodynamic size of the AAm80‐APTAC10‐AMPS10 nano‐ and microgels was studied. The size distribution of nano‐ and microgels derived from DLS data and TEM images was compared as a function of monomer concentration at constant surfactant concentration (6 wt%), HLB = 5.5 and mixture of water:oil = 60:40 vol%. Swelling of microgel particles in saline water due to the antipolyelectrolyte effect was observed. The applicability of amphoteric microgels AAm80‐APTAC10‐AMPS10 for oil recovery was tested on cores simulating the conditions of a model oil reservoir. The obtained results indicated that after the injection of around three pore volumes of the 2500 ppm microgel suspension into the sandstone core the permeability to brine decreased from 1.5 to 0.78 mD. For the first half of core sample the residual resistance factor was higher than the resistance factor, whereas for the second part of core sample these parameters were almost equal. Additional experiments with longer cores are needed to evaluate in‐depth propagation of microgels and permeability reduction in porous media.

Electrochemical supercapacitor based on polyaniline/bismuth-doped zinc oxide (PANI/Bi–ZnO) composite for efficient energy storage

The performance of high-rate supercapacitors is greatly controlled by the electrical and morphological properties of electrodes. Owing to its unique behavior, polyaniline (PANI) is considered one of the best materials for storing energy. This study emphasizes the fabrication of PANI and PANI/bismuth-doped zinc oxide (PANI/Bi–ZnO) as electrode materials for high-efficiency supercapacitors. The pure PANI and its composite were synthesized through inverse emulsion polymerization and investigated for structural and morphological characterization using UV/Vis spectroscopy, Fourier-transform infrared spectroscopy, thermogravimetric analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. These characterization techniques showed that the fabricated materials were suitable for supercapacitor electrodes with improved structural, thermal, and morphological properties. Electrochemical impedance spectroscopy, galvanostatic charging–discharging, and cyclic voltammetry were used to investigate the electrochemical properties. The PANI-based electrode showed ∼564.23 F/g charge storage capacity with ∼60% of capacitance retention, which correspondingly increased to ∼914.05 F/g and ∼88% in PANI/Bi–ZnO composite even after 10,000 charge–discharge cycles. The PANI/Bi–ZnO composite also displayed remarkably high energy density (∼2189.90 Wh/kg) and power density (∼38480.42 W/kg) values. The fabricated electrode is expected to have a large capacity for storing energy and power in commercial electrochemical electrodes.

Effects of synthesis parameters on the performance of crosslinked Co-polymers with clays for conformance control

Conformance control or water shut-off is a technique used to improve oil recovery. During conformance control, polymers block high permeability water areas and redistribute water drive toward unswept oil zones. In this study, co-polymers (denoted ATP-PGV/AM-co-AMPS) were synthesized using acrylamide (AM) and 2-acrylamide-2-methylpropane sulfonic acid (AMPS) as the monomers, polyethylene glycol (PEG)-200 and methylenebisacrylamide (MBA) as the crosslinkers, attapulgite (ATP) and bentonite (PGV) as the clay types, and ammonium persulfate (APS) as the initiator, in addition to paraffin oil and surfactants. Samples were synthesized using inverse emulsion polymerization with different concentrations of monomers, crosslinkers, and clays, and they were characterized using Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). FTIR spectra of the samples confirmed the existence of sulfonate and hydroxyl groups, which are important for polymer swelling. SEM-EDX images indicated that the morphology and elemental composition were different before and after swelling, confirming the occurrence of swelling. Moreover, samples were placed in sodium chloride solution (20,000 ppm) for 7 days to evaluate swelling at both room temperature and 90 °C. Thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) were used to determine the thermal characteristics of the microparticles. Finally, rheological measurements were used to assess the deformation and rheological behavior of the hydrogels. The results showed that after 1 day, good swelling without loss of mechanical strength was achieved with the composite synthesized using 10% AM, 15% AMPS, 6% PGV, and 10% ATP.

Compartmentalized Polyampholyte Microgels by Depletion Flocculation and Coacervation of Nanogels in Emulsion Droplets.

In pH-responsive drug carriers, the distribution of charges has been proven to affect delivery efficiency but is difficult to control and verify. Herein, we fabricate polyampholyte nanogel-in-microgel colloids (NiM-C) and show that the arrangement of the nanogels (NG) can easily be manipulated by adapting synthesis conditions. Positively and negatively charged pH-responsive NG are synthesized by precipitation polymerization and labelled with different fluorescent dyes. The obtained NG are integrated into microgel (MG) networks by subsequent inverse emulsion polymerization in droplet-based microfluidics. By confocal laser scanning microscopy (CLSM), we verify that depending on NG concentration, pH value and ionic strength, NiM-C with different NG arrangements are obtained, including Janus-like phase-separation of NG, statistical distribution of NG, and core-shell arrangements. Our approach is a major step towards uptake and release of oppositely charged (drug) molecules.

Preparation of ammonium polyacrylate thickener via inverse emulsion polymerization: paste forming ability and rheological property

In this work, ammonium polyacrylate (NH4PAA) thickener was synthesized by the inverse emulsion polymerization method with acrylic acid and ammonia water as the aqueous monomer, C16–C31 n-alkanes (5# white oil) as the continuous phase, Span 80/Tween 80 as composite emulsifiers, and Tween 80 as the phase inversion agent, under the action of ammonium persulfate-sodium bisulfite initiation (APS-NaHSO3) and N, N’-methylene-bis-acrylamide (MBA) crosslinking. Gel permeation chromatography and Fourier transform infrared spectroscopy provided evidence for the synthesis of NH4PAA, with a molecular weight of 232,000. The carboxylic content and nitrogen content of the NH4PAA thickener are 23.5% and 3.37%, respectively. A response surface analysis and single factor experiment showed that the optimum synthesis conditions of the NH4PAA thickener were pH 6.5, monomer dosage 38.49 wt%, reaction temperature 45.5°C, initiation system APS and NaHSO3 (weight ratio 1:2) 0.34 wt%, MBA dosage 0.15%, and reaction time 3.2 h. The viscosity of the NH4PAA thickener is 15.7 Pa·s (under the condition of using a rotary rheometer for testing, the mass fraction of the thickener is 3 wt%), which exceeded the corresponding viscosity of diPh-2-CUM-O, SAMXG8 reported in the literature and commercial thickeners. Transmission electron microscopy showed that the NH4PAA thickener presented spherical morphology. Dynamic light scattering showed that the particle size was concentrated at 78.8 nm. A rheological test showed that the NH4PAA thickener was a pseudoplastic fluid with good thixotropy. The NH4PAA thickener gave nylon carpet good printability after jet printing. This work provides a theoretical basis for the development of high-quality thickeners for carpets in jet printing.

Study on the Synthesis and Properties of a New Salt-Resistant Drag Reducer

Summary To solve the problem of poor salt resistance of conventional drag reducers, a hydrophobic associative polymer drag reducer was prepared by inverse emulsion polymerization with acrylamide (AM), methacrylic acid (MAA), 2-acrylamide-2-methylpropane sulfonic acid (AMPS), and hexadecyl dimethyl allyl ammonium chloride (C16DMAAC) as the main monomers. The synthetic product was confirmed as the target product by infrared (IR), nuclear magnetic resonance (NMR), and mass spectrometry (MS). The viscosity-average molecular weight of the prepared drag reducer is 1100×104 g/mol. The pipeline friction results show that the drag reducer has good friction reduction and salt resistance. When the concentration in clean water is 0.06%, the maximum friction reduction rate is 71.1%. When the salinity is 5×104 mg/L, the calcium ion concentration is 2000 mg/L, and the suspended solid content is 500 mg/L, the maximum friction reduction rate is 68.9% when the concentration of the drag reducer is 0.06%. Salt water will not significantly lower the friction reduction rate. If the concentration of the drag reducer is increased to 0.08%, the maximum drag reduction rate will reach 73.8%. The microrheological test results of the friction reducer solution show that, at 0.2% concentration, there is no network structure between friction reducer molecules, which is consistent with Newtonian fluids possessing a certain viscosity. The elasticity index (EI) of the drag reducer solution is basically unchanged over time, maintaining good friction reduction and sand-carrying performance during the shearing process of large displacement pumping.

A Submicron-Scale Plugging Agent for Oil-Based Drilling Fluid Synthesized Using the Inverse Emulsion Polymerization Method

Due to the increasing difficulty of drilling in the later stages of oil and gas field development, the development of micro-pores and micro-fractures is becoming common. Conventional plugging agents have relatively large particle sizes. So, choosing the appropriate plugging agent can prevent leakages. Using the inverse emulsion polymerization method, acrylamide, 2-acrylamide-2-methylpropane sulfonic acid and acrylic acid were selected to be the main reaction monomers, N,N′-methylenebisacrylamide was used as a crosslinking agent, sorbitan monostearate and polyoxyethylene sorbitan anhydride monostearate were used as emulsifiers, and 2,2′-azobis(2-methylpropionamidine) dihydrochloride was used as the initiator to synthesize a nano-scale plugging agent for oil-based drilling fluid. The plugging agent was characterized using infrared spectroscopy, scanning electron microscopy, and thermogravimetry analysis. The results showed that the plugging agent is spherical and uniform in size, with particles being in the submicron range. Additionally, it exhibited strong temperature resistance. Finally, the performance of the plugging agent was evaluated via experiments conducted under normal temperature and pressure, high-temperature and high-pressure, and core-plugging conditions. After adding the plugging agent to the oil-based drilling fluid, the basic rheological properties of the oil-based drilling fluid were not significantly affected. Furthermore, the filtration loss was significantly reduced under normal temperature and pressure, as well as under high-temperature and high-pressure conditions, after aging. When the plugging agent with 3% concentration was added, the reduction rate of pore core permeability reached 96.04%. Therefore, the plugging agent for the oil-based drilling fluid can effectively improve the wellbore stability and has a promising potential for field applications.

Micro-nano polymer microspheres as a plugging agent in oil-based drilling fluid

The wellbore instability of shale formations with micro fractures was mainly ascribed to drilling fluid invasion and pressure transmission during drilling using oil-based drilling fluids (OBDF). Nano-plugging agents or micro-plugging agents at present only match a narrow size range of nanopores or microcracks. Plugging agents with good suitability to multidimensional fractures used in OBDF are lacking. This paper synthesized micro-nano polymer microsphere dispersion (PMD) with a solid content of 30 % through inverse emulsion polymerization. PMs had good wettability for water in the oil environment. The filtration of the emulsion with 4 % PMD dropped the filtration through 0.1–3 µm filters to within 14 mL while the emulsion with 1 % CaCO3 only plugged the filter with a pore size of 3 µm. Hydrophilic PMs with a wide size distribution have excellent suitability with multi-scale pores or cracks. PMs could reduce the filtration of OBDF after aging at 120 and 150 ℃ without significantly influencing their rheology and electrical stability. Based on Darcy’s law, the HTHP mud cake permeability calculated decreased by half with the addition of PMD at 120 and 150 ℃. Moreover, the addition of PMD could decline the disc HTHP filtration by 100–50 % when the disc diameter was 5–120 µm respectively. Compared with CaCO3, the PMD showed superior plugging performance and self-suitability when plugging 5–120 µm discs. Micro-nano PMs could interact with organic clays through hydrogen bonds to form thinner and denser mud cakes. They could also form hydrogen bonds with the formation surface. PMs could enter, aggregate and arrange tightly at multi-scale pores or cracks owing to their wide size distribution. In addition, they formed a dense plugging layer and prevent the filtration from invading the formation. The PMD with good compatibility, suitability and plugging performance has a promising application prospect in shale oil and gas exploration.

Synthesis and characterization of PNM@IAM core-shell microgels through inverse emulsion polymerization and its application for heavy metal ions capture

In this study, thermo and pH-sensitive multifunctional poly (N-isopropylacrylamide-co- N,N’-methylenebisacrylamide, Poly(NIPAAm-co-MBA) - (N-4-amino-2-methylene-4-oxobutanoic acid, IAM) named as (PNM@IAM) core-shell microgels are synthesized by inverse microemulsion polymerization technique using two monomers, N-isopropylacrylamide (NIPAAm) and N-4-amino-2-methylene-4-oxobutanoic acid (IAM). The formation of the microgels are confirmed by 1H nuclear magnetic resonance (1H NMR) and attenuated total reflection fourier transform infrared (ATR-FTIR) spectra. The light transmittance study shows that the microgels prepared at different concentrations and pHs exhibit different physical properties. The phase transition temperature is increased with the addition of IAM. Dynamic light scattering (DLS) analysis reveals that the swelling of the microgels at basic environment is due to the deprotonation of the weak acid groups in IAM. The metal ion chelating test shows that the core-shell PNM@IAM could effectively absorb metal ions in highly basic environment. The absorption and release of heavy metal ions from aqueous solution could be controlled by adjusting the pH of the reaction environment.

Synthesis and Plugging Performance of Nano-Micron Polymeric Gel Microsphere Plugging Agents for Oil-Based Drilling Fluids

As shale gas recovery progresses to deep layers, the wellbore instability during drilling in applications of oil-based drilling fluids (OBFs) becomes increasingly severe. This research developed a plugging agent of nano-micron polymeric microspheres based on inverse emulsion polymerization. Through the single-factor analysis with respect to the permeability plugging apparatus (PPA) fluid loss of drilling fluids, the optimal synthesis conditions of polymeric microspheres (AMN) were determined. Specifically, the optimal synthesis conditions are as follows: the monomer ratio of 2-acrylamido-2-methylpropanesulfonic acid (AMPS): Acrylamide (AM): N-vinylpyrrolidone (NVP) were 2:3:5; the total monomer concentration was 30%; the concentrations and HLB values of emulsifier (Span 80: Tween 60) were 10% and 5.1, respectively; the oil-water ratio of the reaction system was 1:1; the cross-linker concentration was 0.4%. The polymeric microsphere (AMN) produced via the optimal synthesis formula had the corresponding functional groups and good thermal stability. The size distribution of AMN ranged mainly from 0.5 to 10 μm. The introduction of AMND in OBFs can increase the viscosity and yield point of oil-based drilling fluids and slightly decrease the demulsification voltage but significantly reduce high temperature and high pressure (HTHP) fluid loss and permeability plugging apparatus (PPA) fluid loss. The OBFs with 3% polymeric microsphere dispersion (AMND) reduced the HTHP and PPA fluid loss by 42% and 50% at 130 °C, respectively. In addition, The AMND maintained good plugging performance at 180 °C. The AMN particles can block leakoff channels of artificial cores, effectively prevent the invasion of oil-based drilling fluids into formations and suppress pressure transfer. OBFs with 3% AMND enabled the corresponding equilibrium pressure to decrease by 69%, compared with that of the OBFs. The polymeric microspheres had a wide particle size distribution. Thus, they can well match leakage channels at various scales and form plugging layers via compression-deformation and packed accumulation, so as to prevent oil-based drilling fluid from invading formations and improve wellbore stability.

High-performance polyethylenimine-functionalized lignin/silica porous composite microsphere for the removal of hexavalent chromium, phosphate and Congo red from aqueous solutions

Based on lignin derived from nature, polyethylenimine-functionalized lignin/SiO2 porous composite microspheres (LSPGs) were prepared by inverse emulsion polymerization in this article. The experimental parameters were optimized via orthogonal experiments, and the removal performance of LSPGs for common anionic pollutants was comprehensively investigated. The equilibration times required for the adsorption of Cr(VI), PO43- and Congo red by LSPGs were 2.0 h, 0.75 h and 3.0 h, respectively. The removal process of these pollutants mainly relied on chemical adsorption. The highest adsorption capacity of LSPGs for Cr(VI), PO43- and Congo red calculated by Langmuir model were 355.21 mg g−1, 313.48 mg g−1 and 588.24 mg g−1, respectively. In the presence of different anions, LSPGs showed good selectivity for Cr(VI), while SO42- had a strong inhibitory effect on the enrichment of PO43-. Electrostatic attraction adsorption mechanism played an important role in the removal of pollutants. In addition, redox, hydrogen bonding and π-π interactions also had irreplaceable abilities in the removal of Cr(VI), PO43- and Congo red, respectively. For the three target ions, the LSPGs that underwent five adsorption-desorption cycles still retained more than 80% adsorption capacity. The results showed that composite microspheres LSPGs can effectively remove PO43--containing, Cr(VI)-containing and organic dye wastewater.

Synthesis and plugging effect of inverse emulsion polymerization microspheres (OPME) for oil-based drilling fluids

It is difficult to seal oil-based drilling fluids in the large pore and micro-fracture formation, and there are few suitable materials for the oil phase with good sealing ability at present. In order to solve the problem of the lack of sealing ability of oil-based drilling fluids, acrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and acryloyl morpholine were used as monomers, N'N-methylenebisacrylamide was used as a cross-linking agent, Span-80 and Tween-60 were used as emulsifiers, and 2,2′-azobis(2-methylpropionamidine) dihydrochloride was used as an initiator. Polymer microsphere emulsion OPME was synthesized by inverse emulsion polymerization. The structure of polymer microspheres was characterized by infrared spectroscopy, scanning electron microscopy, electron microscopy, H NMR, laser particle size analysis and thermogravimetric analysis. The optimal synthesis conditions were determined by the control variable method: the monomer ratio of acrylamide, 2-acrylamido-2-methylpropane sulfonic acid, and acryloyl morpholine was 45:20:15, the amount of emulsifier was 8%, and the reaction temperature was 55℃. The synthetic polymer microspheres were added to the oil-based drilling fluids to perform filtration and loss plugging at atmospheric pressure and high-temperature and high-pressure, as well as pore and artificial fracture core plugging evaluation. The evaluation results show that the permeability reduction rate of pore core can reach 82%, and that of fracture core can reach 100% by adding polymer microspheres with 3% dosage. Finally, the pressure transmission experiment proves that the addition of polymer microspheres can slow the pressure transmission and filtrate intrusion, and enhance the stability of wellbore. Therefore, polymer microspheres are a micron-level plugging agent with good compatibility and high performance with oil-based drilling fluids, and the 3% dosage can better seal the formation of large pores and micro-fractures, which has a good potential for field application.

Investigation of Alumina-Doped Prunus domestica Gum Grafted Polyaniline Epoxy Resin for Corrosion Protection Coatings for Mild Steel and Stainless Steel.

Eco-friendly inhibitors have attracted considerable interest due to the increasing environmental issues caused by the extensive use of hazardous corrosion inhibitors. In this paper, environmentally friendly PDG-g-PANI/Al2O3 composites were prepared by a low-cost inverse emulsion polymerization for corrosion inhibition of mild steel (MS) and stainless steel (SS). The PDG-g-PANI/Al2O3 composites were characterized by different techniques such as X-ray diffraction (XRD), UV/Vis, and FTIR spectroscopy. XRD measurements show that the PDG-g-PANI/Al2O3 composite is mostly amorphous and scanning electron micrographs (SEM) reveal a uniform distribution of Al2O3 on the surface of the PDG-g-PANI matrix. The composite was applied as a corrosion inhibitor on mild steel (MS) and stainless steel (SS), and its efficiency was investigated by potentiodynamic polarization measurement in a 3.5% NaCl and 1 M H2SO4 solution. Corrosion kinetic parameters obtained from Tafel evaluation show that the PDG-g-PANI/Al2O3 composites protect the surface of MS and SS with inhibition efficiencies of 92.3% and 51.9% in 3.5% NaCl solution, which is notably higher than those obtained with untreated epoxy resin (89.3% and 99.5%). In particular, the mixture of epoxy/PDG-g-PANI/Al2O3 shows the best performance with an inhibition efficiency up to 99.9% on MS and SS. An equivalent good inhibition efficiency was obtained for the composite for 1M H2SO4. Analysis of activation energy, formation enthalpy, and entropy values suggest that the epoxy/PDG-g-PANI/Al2O3 coating is thermodynamically favorable for corrosion protection of MS and exhibits long-lasting stability.

Synthesis, Optimization, and Characterization of Fluorescent Particle Preformed Gel

Performed gels are widely used in fields to support profile modification and Enhance Oil Recovery. Previous studies of profile modification of performed gels mainly used the index of pressure, resistance factor, or residual resistance factor to represent their ability. However, there is a lack of methods available to directly study their modification ability. In this article, the preformed gels with fluorescence properties, CQDs@PPG, would provide a new way to explore the profile modification of preformed gels. This paper uses poly (acrylamide, sodium p-styrene sulfonate), carbon quantum dots, and N,N-methylenebisacrylamide to prepare the CQDs@PPG via inverse emulsion polymerization. The morphology, size distribution, structure, fluorescence characteristics, surface potential thermal stability, viscosity changes, and viscoelastic properties of CQDs@PPG were analyzed. Moreover, the fluorescence properties of CQDs@PPG under different temperature, salinity, and pH were examined. Results indicate that the CQDs@PPG have excellent stability and that pH and salinity have little influence on their fluorescence properties. Further, only the temperature would affect the fluorescence properties of CQDs@PPG, but that effect is reversible after the temperature drops. By examining the fluorescence intensity, it would be more direct for researchers to study the profile modification in further experiments.

Swelling-Mediated Mechanical Stimulation Regulates Differentiation of Adipose-Derived Mesenchymal Stem Cells for Intervertebral Disc Repair Using Injectable UCST Microgels.

Mechanical stimulation is an effective approach for controlling stem cell differentiation in tissue engineering. However, its realization in in vivo tissue repair remains challenging since this type of stimulation can hardly be applied to injectable seeding systems. Here, it is presented that swelling of injectable microgels can be transformed to in situ mechanical stimulation via stretching the cells adhered on their surface. Poly(acrylamide-co-acrylic acid) microgels with the upper critical solution temperature property are fabricated using inverse emulsion polymerization and further coated with polydopamine to increase cell adhesion. Adipose-derived mesenchymal stem cells (ADSCs) adhered on the microgels can be omnidirectionally stretched along with the responsive swelling of the microgels, which upregulate TRPV4and Piezo1channel proteins and enhance nucleus pulposus (NP)-like differentiation of ADSCs. In vivo experiments reveal that the disc height and extracellular matrix content of NP are promoted after the implantation with the microgels. The findings indicate that swelling-induced mechanical stimulation has great potential for regulating stem cell differentiation during intervertebral disc repair.

Influence of acidic and alkaline environmental anticorrosive performance of epoxy coatings based on polyaniline/carbon nanotube hybrids modified with ionic liquid

Polyaniline (PAni) and their hybrids with carbon nanotube (PAni@CNT) were prepared through inverse emulsion polymerization of aniline in the presence of different amounts of the ionic liquid (IL), 1-butyl-3-methyl-imidazolium tetrafluorborate (bmim.BF4). Transmission electron microscopy (TEM) was used to evaluate the morphology of the particles and cyclic voltammetry was employed to evaluate the electroactivity of these compounds in different pH media. The presence of IL promoted a great improvement of the redox activity of PAni@CNT in acidic medium and PAni in acidic and neutral media. Epoxy-based coatings containing 1 % of PAni and PAni@CNT were applied on carbon steel substrate to investigate their corrosion resistance using electrochemical impedance spectroscopy (EIS) technique. The coatings, deliberately scratched, were immersed in acidic and alkaline media. PAni@CNT hybrid presented better anti-corrosion response than PAni in acidic, neutral and alkaline environments and the presence of IL resulted in additional improvement of this property in all media. These results provide new possibilities for the preparation of environmentally friendly coating to be effective in a wide range of pH media. The morphology and band gap energy of the ER-based films were also investigated by optical micrograph and ultraviolet-visible spectroscopy, respectively. Narrower band gap energy was observed for the films containing hybrid materials mainly those containing IL in the hybrid, probably due to the improvement of charge transfer between particles promoted by the IL.