Inverse Emulsion Polymerization Research Articles

Synthesis and characterization of highly sensitive ammonia sensor based on polyaniline/bismuth doped zinc oxide composites

AbstractHighly efficient gas sensors fabrication having low detection limits have been one of key research area due to the industrial, environmental and other technological applications. In this study, polyaniline/bismuth doped zinc oxide (PANI/Bi‐ZnO) was prepared via inverse emulsion polymerization and it was coated over a substrate with staggered electrodes to create a highly efficient ammonia (NH3) sensor. The UV/Vis investigation, fourier transformed infrared (FTIR), raman spectral analysis, and scanning electron microscopy (SEM) were used to describe the structure and morphology of prepared samples. At room temperature, the PANI/Bi‐ZnO sensor's sensitivity to various NH3 gas concentrations ranging from 20 to 100 ppm was examined. According to the experimental findings, the PANI/Bi‐ZnO film exhibits outstanding performance of response and selectivity. The response at 20 ppm NH3 was as high as ⁓100%. The response and recovery time was also calculated at 20 ppm and was 11/15 s. The contact between p‐n heterojunctions in the composite is responsible for the exceptional sensitivity of PANI/Bi‐ZnO towards NH3 sensing.Highlights Synthesis of Bi doped ZnO composites with PANI at room temperature Fabrication of highly sensitive and efficient resistive type ammonia sensor Selective and robust detection of ammonia by the fabricated sensor High sensitivity with low limit of detection offered by the sensor Response of the fabricated sensor at 20 ppm NH3 was as high as ⁓100%

PH-switchable W/O drag reducer emulsions based on dynamic covalent stabilizers for efficient stabilization and rapid dissolution of drag reducers

As the global emphasis on shale oil extraction grows, there is a rising demand for slickwater fracturing fluids for reservoir stimulation. Polyacrylamide drag reducers plays a crucial role in slickwater and are available in two primary forms: powder and emulsion. Powder-based drag reducers suitable for long-term transportation and storage, but increasing their dissolution rate remains a challenge. While emulsion-based drag reducers are valued for the efficient dissolution facilitated by hydrophilic phase-inversion surfactants, the incorporation of the surfactants compromise the stability of W/O emulsions. In this work, an imine-functionalized pH-switchable stabilizer was synthesized, and the W/O emulsion constructed with the stabilizer underwent demulsification at a pH of 4.9. The pH-switchable emulsion system was optimized, and inverse emulsion polymerization using the stable monomer emulsion was performed for preparing pH-switchable drag reducer emulsions. The drag reducer emulsion features remarkable resistance to instability even after 30 days of storage owing to the absence of phase-inversion surfactants. The imine bond on the stabilizer was cleaved in acid solution, allowing the switchable drag reducer emulsion to be rapidly released and dissolved in water at pH 2.75, boasting an impressive dissolution rate of only 150 s. Furthermore, the pH-switchable drag reducer emulsion demonstrated effective drag-reduction performance, achieving a drag-reduction rate as 73 % at a concentration of 0.06 wt%. The pH-switchable drag reducer emulsion effectively resolves the conflict between rapid dissolution and efficient stabilization of drag reducer, thus offering potential improvements in the formulation process of slickwater and the efficiency of shale oil development.

Preparation of magnetic Fe3O4/PAM composite microspheres by inverse emulsion polymerization

The stable micro-aqueous groups (MAGs) were prepared by using sodium dodecyl sulfate (SDS) and sorbitan fatty acid ester (Span80) as emulsifiers. Fe3O4/PAM composite microspheres (CMPs) were obtained by inverse emulsion polymerization in MAGs. The experimental results showed that the size of the spherical Fe3O4/PAM CMPs was about 135-420nm and the saturation magnetization value of them was about 23.3emu/g. In the Fe3O4/PAM CMPs, the mass fraction of PAM was about 76.5%. The viscosity of the emulsion containing Fe3O4/PAM CMPs increased with the increase of current and decreased with the increase of shear rate

Insights into the Efficient Release of the Polyacrylamide Drag Reducer via a pH-Responsive Inverse Polymer Emulsion.

The enormous demand for petroleum consumption has resulted in the shortage of fossil resources, prompting the need to explore unconventional reservoirs. Polyacrylamide emulsion drag reducers are capable of inhibiting the turbulence of fracturing fluids for enhancing the reservoir stimulation results, but the poor dissolution efficiency of polyacrylamide emulsion drag reducers is the primary limitation to their large-scale application. Here, a pH-responsive ionic liquid surfactant, oleic acid/cyclohexanediamine (HOA/HMDA), is synthesized by using oleic acid (HOA) and cyclohexanediamine (HMDA). HOA/HMDA shows a remarkable pH-responsive behavior due to the pH-induced deconstruction of the HOA/HMDA structure. Interestingly, the HOA/HMDA-stabilized monomer emulsion exhibits an obvious pH-induced emulsion structure transformation behavior. In addition, the HOA/HMDA-stabilized monomer emulsion possesses excellent dynamic and storage stability, supporting the inverse emulsion polymerization of the polymer P(AM/AMPS/AA). The obtained P(AM/AMPS/AA) polymer inverse emulsions maintained stability for 30 days. Our finding proposes that the structure of the P(AM/AMPS/AA) polymer inverse emulsions changes with pH stimulation, which is capable of facilitating the release of polymers. P(AM/AMPS/AA) is released from the P(AM/AMPS/AA) polymer inverse emulsions within 30 s at a pH value of 12.06, along with a drag reduction rate of 62.54%. Obviously, the HOA/HMDA-stabilized P(AM/AMPS/AA) polymer inverse emulsions eliminate the contradiction between the stability and release of polyacrylamide emulsion drag reducers, which is promising for meeting the demands of reservoir stimulation.

Experimental Investigation and Computational Insights of Enhanced Rheological Stability of Water-Based Drilling Fluids by Microspherical Polymers

Summary 3D bulk polymer, as an alternative to linear polymer, has exhibited large potential in formulating high-performance water-based drilling fluids. Understanding the mechanism behind the enhanced rheological stability of drilling fluids by microspherical polymers is critical for designing and developing new high-performance drilling fluids. In this work, we conducted a pioneering investigation that integrated experimental techniques with computational modeling, to explore the enhancement mechanism involved in the targeted drilling fluids. Inverse emulsion polymerization experiments were first carried out to fabricate the microspherical polymer acrylic acid (AA), acrylamide (AM), and 2-acryloylamino-2-methyl-1-propanesulfonic acid [P(AA-AM-AMPS)], and then physicochemical properties of microspherical polymer were characterized. Subsequently, the performance of drilling fluids with microspherical polymer as an additive was systematically evaluated. Finally, molecular simulations were used to investigate the characteristics of chemical active sites, molecular conformation, and structural variation at various temperatures. The results showed that the final microspherical polymer has a core-shell structure, with an average size of 198.3 nm and a molecular weight of 6.2×106 g/mol. The 3D structure exhibits good thermal stability, and thermal decomposition occurs above 220°C. The drilling fluids formulated with the microspherical polymer showed better rheological stability in the medium-low (4–65°C) and medium-ultrahigh (40–240°C) temperature ranges, compared with the relevant drilling fluids with the parallel linear polymer. Analyses on electrostatic potentials (ESPs) and frontier molecular orbital (FMO) revealed that active groups within the confined sphere domain mainly include carbonyl C = O and amide -CO(NH2). Additionally, these active groups exhibit a hierarchical distribution in the outer molecular region. Analyses on the radius of gyration (Rg) and the radial distribution function g(r) further validated the core-shell structure of microspherical polymer and its temperature-resistant stability. Moreover, a new self-consistent structural compensation model was proposed to rationalize the structure-activity relationship of microspherical polymer in drilling fluids. The computational results align well with the experimental findings. This pioneering work will provide valuable information for both the synthesis of new functional additives and the formulation of tailored-performance drilling fluids.

Optimization of synthesis conditions and calibration of water-swellable polyacrylamide microgels

Precipitation Polymerization (PP) and Inverse Emulsion Polymerization (IEP) are the main procedures widely used for the synthesis of microgels from acrylamide derivate monomers, in both academic and industrial spheres. Here, these procedures were optimized for pure acrylamide monomer to synthetize a “model” polyacrylamide microgel targeting a minimized size of approximately 200 nm in radius. For this neutral and non-responsive monomer, the role of the co-solvent in PP and co-surfactant in IEP was discussed. This work demonstrates the crucial step of purification and calibration on microgels physical properties in suspension. In particular, the filtration step has a significant impact on their rheological behaviour, where the flow properties requiring a complex description become analysable with a standard Carreau–Yasuda model. In summary, this paper provides a systematic discussion on the role of each step in the elaboration of model microgel, as a routine checklist to be considered before further physical-chemical studies.

Dual-functional metal-organic frameworks-based hydrogel micromotor for uranium detection and removal

Self-propelled micro/nanomotors have attracted great attention for environmental remediation, however, their use for radioactive waste detection and removal has not been addressed. Engineered micromotors that are able to combine fast detection and highly adsorptive capability are promising tools for radioactive waste management but remain challenging. Herein, we design self-propelled micromotors based on zeolite imidazolate framework (ZIF-8)-hydrogel composites via inverse emulsion polymerization and show their potential for efficient uranium detection and removal. The incorporation of magnetic ferroferric oxide nanoparticles enables the magnetic recycling and actuation of the single micromotors as well as formation of swarms of worm-like or tank-treading structure. Benefited from the enhanced motion, the micromotors show fast and high-capacity uranium adsorption (747.3 mg g−1), as well as fast uranium detection based on fluorescence quenching. DFT calculation confirms the strong binding between carboxyl groups and uranyl ions. The combination of poly(acrylic acid-co-acrylamide) with ZIF-8 greatly enhances the fluorescence of the micromotor, facilitating the high-resolution fluorescence detection. A low detection limit of 250 ppb is reached by the micromotors. Such self-propelled micromotors provide a new strategy for the design of smart materials in remediation of radioactive wastewater.

A highly tuneable inverse emulsion polymerization for the synthesis of stimuli-responsive nanoparticles for biomedical applications.

Polymeric nanomaterials have seen widespread use in biomedical applications as they are highly tuneable to achieve the desired stimuli-responsiveness, targeting, biocompatibility, and degradation needed for fields such as drug delivery and biosensing. However, adjustments to composition and the introduction of new monomers often necessitate reoptimization of the polymer synthesis to achieve the target parameters. In this study, we explored the use of inverse emulsion polymerization to prepare a library of polymeric nanoparticles with variations in pH and temperature response and examined the impact of overall batch volume and the volume of the aqueous phase on nanoparticle size and composition. We were able to prepare copolymeric nanoparticles using three different nonionic and three different anionic comonomers. Varying the non-ionizable comonomers, acrylamide (AAm), 2-hydroxyethyl methacrylate, and N-isopropylacrylamide (NIPAM), was found to alter the mass percentage of methacrylic acid (MAA) incorporated (from 26.7 ± 3.5 to 45.8 ± 1.8 mass%), the critical swelling pH (from 5.687 ± 0.194 to 6.637 ± 0.318), and the volume swelling ratio (from 1.389 ± 0.064 to 2.148 ± 0.037). Additionally, the use of NIPAM was found to allow for temperature-responsive behavior. Varying the ionizable comonomers, MAA, itaconic acid, and 2-acrylamido-2-methylpropane sulfonic acid (AMPSA), was found to significantly alter the critical swelling pH and, in the case of AMPSA, remove the pH-responsive behavior entirely. Finally, we found that for the base P(AAm-co-MAA) formulation, the pH-responsive swelling behavior was independent of the scale of the reaction; however, variations in the aqueous volume relative to the volume of the continuous phase significantly affected both the nanoparticle size and the critical swelling pH.

Synthesis and characterization of novel poly cysteine methacrylate nanoparticles and their morphology and size studies.

Polymer nanoparticles (PNPs) have significantly advanced the field of biomedicine, showcasing the remarkable potential for precise drug delivery, administration of nutraceuticals, diagnostics/imaging applications, and the fabrication of biocompatible materials, among other uses. Despite these promising developments, the invention faces notable challenges related to biodegradability, bioactivity, target-site specificity, particle size, carrier efficiency, and controlled release. Addressing these concerns is essential for optimizing the functionality and impact of PNPs in biomedical applications. Here, new poly cysteine methacrylate nanoparticles (PCMANPs), ca. (200 nm) in size have been synthesized from the cysteine methacrylate (CysMA) monomer using different strategies, including emulsion and inverse emulsion polymerization techniques. The monomer was synthesized using the Michael addition reaction, involving the addition of 3-(acryloyloxy)-2-hydroxypropyl methacrylate to the sulfhydryl group (-SH) of the cysteine (Cys) active site, with the aid of dimethyl phenyl phosphine (DMPP) as a nucleophilic agent as previously reported. To enhance nano-polymerization, a thorough exploration of various initiators, including ammonium persulfate (APS) and 4,4'-azobis (4-cyanovaleric acid) (ACVA), alongside surfactants, such as polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP), and sodium dodecyl sulfate (SDS), was conducted. Additionally, critical parameters, such as reaction time, temperature, and solvents, were systematically investigated due to their substantial influence on the shape, size, stability, and morphology of the synthesized polymer nanoparticles. This comprehensive approach aims to optimize the synthesis process, ensuring precise control over the key characteristics of the resulting nanoparticles for enhanced performance in diverse applications. Various characterization techniques, including field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), nuclear magnetic resonance (NMR), Raman spectroscopy, Fourier-transform infrared spectroscopy (FTIR), zeta potential, and zeta sizer dynamic light scattering (DLS) analysis, were utilized to investigate purity, morphology, and particle size of the PNPs. As a result, a spherical, monodispersed (homogenized), and stable PCMANP with defined size and morphology was achieved. This may exhibit a remarkable achievement in the future of drug delivery systems and therapeutic index.

Enhancement for drag reducer release efficiency from inverse polymer emulsion using pH-responsive dynamic covalent surfactant

The increasing global fossil resources consumption requires convert the sights into the exploitation of tight oil resources. Polymer emulsion drag reducers are widely used in hydraulic fracturing techniques for inhibition of fluid turbulence and reservoir stimulation for enhanced oil recovery. However, the poor release efficiency and requirement for extra hydrophilic surfactant for phase inversion limit the practical application. Herein, a hydrophobic surfactant oleylamine-4-carboxybenzaldehyde (OA-CBA) was synthesized with oleic amine (OA) and 4-carboxybenzaldehyde (CBA). OA-CBA exhibited pH-responsive behavior, attributing to the existence of dynamic covalent bond in OA-CBA. The OA-CBA stabilized monomer emulsions, consisted of acryla-mide (AM), 2-acrylamide-2-methylpropane sulfonic acid (AMPS) and Acrylic acid (AA), suggests remarkable dynamic and storage stability, which supply stable microreactors for polymerization. Furthermore, polymer emulsion with pH-responsive behavior was obtained by inverse emulsion polymerization upon redox initiation. The polymer drag reducer was completely released within 10 s upon adjusting the pH value to 2.26. Notably, the pH-responsive polymer emulsion exhibited 18 times faster release time compared to traditional polymer emulsion stabilized by Span 80, along with a 63.2% drag reduction rate. The rapid release of the polymer was realized by regulating pH merely instead of introduction of extra hydrophilic surfactant, which reconciles the contradiction of stability and release of polymer from emulsions.

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.