Inverse Emulsion Polymerization Research Articles

The efficient metal- and halogen-free polymer catalyst for the intensification on CO2 cycloaddition

An environmentally friendly polymer catalyst (PAS) was synthesized via inverse emulsion polymerization using acrylic acid (AA) and 1-vinyl imidazole (VI) as monomers. The excellent catalytic activity of PAS was attributed to the synergistic effects of the carboxyl groups (-COOH) as hydrogen bond donors and N-heterocyclic carbene (NHCs) as electron donor, as well as the swelling properties of the polymer, which can enrich the substrate into the polymer network, increasing the contact between the substrate and active sites. Characterization results from thermogravimetric (TG) analysis and small-angle X-ray scattering (SAXS) showed that the excessive imidazole addition disrupted the polymer's chain-like structure, significantly reducing its swelling properties. And, the catalytic performance is influenced by both the amount of imidazole in PAS and the swelling properties of the polymer. Finally, the reaction mechanism of the CO2 cycloaddition reaction catalyzed by PAS was proposed and validated through density functional theory (DFT) calculations.

PH- and temperature-dual responsive polymer emulsion for rapid release of drag reducer

Slick water fracturing fluid is widely used in major oil fields due to its low cost and high drag reduction. Polyacrylamide emulsions drag reducers play a decisive role in slick water fracturing. The dissolution rate of polymer emulsions drag reducers was increased by adding hydrophilic surfactants, but the stability of the emulsions is poor, which limits its wide application. In order to solve the contradiction between the stability of polymer emulsion and rapid release of drag reducer. Here, a P(AA-AM-AMPS) polymer emulsion drag reducer with dual stimulation response of pH and temperature was designed. Surfactant (D400/OA) with dual responses to pH and temperature is synthesized by using oleic acid (HOA) and polyether amine 400 (D400). D400/OA shows a remarkable pH- and temperature-responsive behavior due to the pH- and temperature-induced structural transformation of D400/OA. Interestingly, D400/OA-stabilized monomer emulsion exhibits an obvious pH- and temperature-induced structural transformation. Meanwhile, The D400/OA-stabilized monomer emulsion has remarkable stability, which benefits the inverse emulsion polymerization of P(AM-AA-AMPS) polymer. The obtained P(AM-AA-AMPS) polymer emulsion maintain stability whose particle size nearly unchanged by storing for 15 days. Interestingly, P(AM-AA-AMPS) polymer emulsion can be released completely by changing the pH or temperature of the aqueous solution. The apparent viscosity of P(AM-AA-AMPS) polymer, in either the alkaline (pH=10.31) solution of 25±2 °C or neutral (pH=7) solution of 70±2 °C, respectively required 40 s and 8 min to reached a maximum value of 96 mPa·s. The release rate of P(AM-AA-AMPS) polymer emulsion is further enhanced under the dual responsive of temperature (70±2 ℃) and pH (10.31) and it takes only 20 s, In addition, the drag reduction rate of P(AM-AA-AMPS) polymer emulsion is 72 % when completely released under the dual responsive of temperature and pH, showing a remarkable drag reduction property. The D400/OA-stabilized P(AM-AA-AMPS) polymer emulsion are expected to meet the demand for the production enhancement of the oil and gas reservoirs.

Synthesis, characterization, and surface modification of degradable polar hydrophobic ionic polyurethane nanoparticles for the delivery of therapeutics to vascular tissue

Degradable polar hydrophobic ionic polyurethanes (D-PHI) are an emerging class of biomaterials with particular significance for blood-contacting applications due to their immunomodulatory effects and highly customizable block chemistry. In this manuscript, D-PHI polymer was formulated as a nanoparticle excipient for the first time by inverse emulsion polymerization. The nanoparticles were optimized with consideration of diameter, surface charge, size variability, and yield as a delivery vehicle for a custom vascular therapeutic peptide. A layer-by-layer (LBL) surface modification technique using poly-L-lysine was integrated within the nanoparticle design to optimize therapeutic loading efficiency. Solvent pH played a pivotal role in emulsion micelle formation, LBL polymer secondary structure, and the polymer functional group interactions critical for high therapeutic loading. The resulting nanoparticle platform met target size (200 ± 20 nm), polydispersity (<0.07), and storage stability standards, was nontoxic, and did not affect therapeutic peptide bioactivity in vitro. Surface-modified D-PHI nanoparticles can be reproducibly manufactured at low cost, generating a highly customizable excipient platform suitable for delivery of biomolecular therapeutics. These nanoparticles have potential applications in vascular drug delivery via localized infusion, drug eluting stents, and drug-coated angioplasty balloons. Statement of significanceNanoscale excipients have become critical in the delivery of many therapeutics to enhance drug stability and targeted biodistribution through careful design of nanoparticle composition, surface chemistry, and size. This manuscript describes the development of a nanoparticle excipient derived from an immunomodulatory degradable polar hydrophobic ionic polyurethane, in combination with a layer-by-layer surface modification approach utilizing poly-L-lysine, to transport a mimetic peptide targeting smooth muscle cell migration in vascular disease. The nanoparticle platform draws on the effect of pH to maximize drug loading and tailor particle properties. The low cost and easily reproducible system presents a highly customizable platform that can be adapted for therapeutic delivery across a wide range of clinical indications.

Maltodextrin polymer nanospheres as a filtrate reducer for filtration control in water-based drilling fluids

With the development of deep and ultra-deep wells, there is a need to enhance the rheological and filtration properties of water-based drilling fluids under high temperature and salinity conditions. In this study, maltodextrin polymer nanospheres (MDPN) were synthesized through cross-linking maltodextrin and methylene bisacrylamide (MBA) via inverse emulsion polymerization. Then, the polymer MDPN-DAN was synthesized via aqueous solution polymerization, using maltodextrin polymer nanospheres, N, N-dimethylacrylamide (DMAA), 2-acrylamide-2-methylpropanesulfonic acid (AMPS), and N-vinylpyrrolidone (NVP) as raw materials. Structural characterization confirmed the successful synthesis of the polymer MDPM-DAN, with a median particle size of 234.4 nm. Thermogravimetric analysis revealed a thermal decomposition temperature of 242 °C for MDPM-DAN. This polymer demonstrated excellent settling stability at 220 °C in high-temperature and weakly alkaline environments. Rheological assessments demonstrated a 754 % enhancement in the drilling fluid’s rheological properties when MDPM-DAN was added compared to the base mud. MDPM-DAN demonstrated significant reduction in filtration loss, with polymer mud aged at 220 °C showing only 5.6 mL of loss, and polymer mud aged at 220 °C with 15 wt% NaCl exhibiting 8.9 mL loss. The filtration loss reduction mechanism elucidated that MDPM-DAN could adsorb onto bentonite particles via hydrogen bonds, while nanoparticles filled the micropores of the filter cake, promoting the formation of a dense filter cake. Furthermore, plugging experiments showcased MDPM-DAN’s ability to block nano-pore throats, with the molecular chain’s amide groups reinforcing the plugging through hydrogen bonding with rocks, while bentonite coats the micro-pore throats.

On the Mechanism of Nucleation and Monomer Transport in Inverse Emulsion Polymerization

On the Mechanism of Nucleation and Monomer Transport in Inverse Emulsion Polymerization

Synthesis and performance evaluation of low‐damage variable viscosity integrated drag reducer

AbstractTo solve problems such as inadequate proppant carrying capacity, a complex viscosity changing process, and limited environmental friendliness associated with traditional slick water fracturing fluids, a variable viscosity friction reducer called Jianghan friction reducer (JHFR) with low damage, high drag reduction, and strong proppant‐carrying capacity is prepared by inverse emulsion polymerization. The properties of JHFR are investigated by viscometer, JHFR‐II high‐temperature and high‐pressure slick water drag reduction rate tester, surface tension meter, and JHCQ Core dynamic damage evaluation device. The result shows that the dissolution time of JHFR is less than 120 s. The drag reduction of 0.08 wt% JHFR (4.83 mPa s) is 80.3%. When the concentration of JHFR increases from 0.08 to 0.8 wt %, the viscosity of the JHFR increases from 4.83to 97.41 mPa s. After sheared at 90°C and 170 s−1 for 60 min, the viscosity of 0.8 wt% JHFR still maintains 51 mPa s. The damage rate of JHFR to core matrix permeability is lower than 30%. JHFR also shows the advantages of easy breakage and low residue. It provides guidance for the design and selection of fracturing fluid for unconventional oil and gas reservoir development.

A leaf-mimic material based on polyurethane microcapsules and Cr2O3 for hyperspectral stealth

Targets can achieve invisibility in the vegetation environments by simulating the reflection spectra of plant green leaves. However, balancing the accuracy and stability of simulation effects, particularly in simulating spectral features caused by water in the leaves, is often challenging. Herein, polyurethane microcapsules encapsulating liquid water (W-PUMCs) were prepared by inverse emulsion polymerization, then mixed with Cr2O3 in specific proportions into the epoxy resin matrix to obtain a material capable of simulating the reflection spectra of green leaves in the visible and near-infrared bands. The normalized similarity (NS) between the spectrum of this material and that of plant (cherry) green leaf can reach 0.9779 in the range of 400–2500 nm. W-PUMCs are used to simulate the spectral characteristics caused by water in the leaves because the spectral NS between W-PUMCs and the green leaf in the 1100–2200 nm range is 0.9930. Cr2O3 is employed to simulate the other major spectral features of green leaves. This strategy guarantees simulation accuracy while simplifying the preparation process and reducing production costs and providing solutions to spectral simulation in the fields of military stealth and ecological protection.

Preparation and Properties of Temperature Resistant and Salt Resistant Lotion Fracturing Fluid Thickener

In order to prepare fracturing fluid with excellent solubility, temperature resistance, salt resistance and shear resistance, acrylamide (AM), 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and acryloylmorpholine (ACMO) were copolymerized, and anionic cellulose was introduced to synthesize a new type of polyacrylamide copolymer p (AM/AMPS/ACMO) through inverse emulsion polymerization. The structure and morphology were characterized by infrared spectroscopy and scanning electron microscope. The results showed that in 0, 5, 10, 20, 50, 100, 150 and 200 g/L NaCl, CaCl2, and MgCl2 solutions, the viscosity of p (AM/AMPS/ACMO) solution modified by PVA fiber was always higher than that of conventional PAM solution, and the polymer modified by PVA fiber had better salt resistance. The anionic cellulose modified thickener was sheared at 120 ℃ and 150 ℃ for 1 h at 170 s－1, and the viscosity after shearing is 89.92 mPa·s and 80.10 mPa·s, respectively, which is much higher than the viscosity required by the general technical conditions of fracturing fluid more than 50 mPa·s, indicating that anionic cellulose modified p (AM/AMPS/ACMO) has good temperature and shear resistance.

Glycosylated stimuli responsive polyacrylamide microspheres with in-situ formed AgNPs for bacterial capture, detection and killing

Infections due to multidrug resistant bacteria are a major concern and cause for human mortality worldwide. Materials that can selectively capture, and eliminate these pathogens have turned into a priority. Development of excellent point-of-care material/system that can help in the visual detection of the captured bacterial cells in addition to their killing capability can be advantageous. In this study, we demonstrate the synthesis of a hitherto unknown glycosylated gel microspheres that can capture, kill and detect pathogenic bacteria. Silver nanoparticles (AgNPs) loaded glucose/mannose/galactose functionalized microspheres namely; PAM-Glc, PAM-Man and PAM-Gal, were synthesized by inverse emulsion polymerization. The sugar functionalities present on the microspheres interacts with the bacterial cell wall leading to capture of the cells while the antibacterial action was brought about by the AgNPs synthesized in-situ within the microspheres. The highlight of the designed system is visual indication of bacterial capture due to aggregation of gel microspheres and an indicative colour change of AgNPs. The capture kinetics of bacterial cells using PAM-Man was faster compared to PAM-Glc and PAM-Gal. Among the AgNPs loaded glyco microspheres, silver loaded mannose microspheres (Ag@PAM-Man) exhibited greater inhibition against E. coli and antibiotic resistant S. aureus cells. Bacterial cells captured by PAM-Man, exhibited pink coloration upon interaction with Resorufin β-glucuronide; suggesting the destruction of bacteria upon adhesion to microspheres. The plausible mechanistic aspects involved in the capture, detection and killing process is also discussed.

Synthesis and Characterization of a Temperature-Sensitive Microcapsule Gelling Agent for High-Temperature Acid Release.

Deep, high-temperature carbonate reservoirs, represented by the Chuanzhong-Gaomo Block and the Penglai Gas Field, have become important supports for increased storage and production in Sichuan Basin. However, acidization in high-temperature to ultrahigh-temperature reservoirs faces several technical challenges, such as fast acid-rock reaction rates, limited acid corrosion distances, and high risks of tubular corrosion. In this study, a novel high-temperature-resistant microencapsulated gelling agent GLE-3 was prepared using N-isopropylacrylamide (NIPAM) as the wall material, acrylamide (AM), 2-acrylamido-2-methylpropanesulfonic acid (AMPS), and N-vinylcaprolactam (NVCL) as the core materials, and N,N'-methylenebis(acrylamide) (MBA) as the cross-linking agent through inverse emulsion polymerization. GLE-3 was structurally characterized using infrared spectroscopy, transmission electron microscopy, and particle size analysis, and its properties were evaluated. The results showed that GLE-3 exhibited uniform particle size distribution ranging from 10 to 100 μm. Under high-temperature conditions of 180 °C and a shear rate of 170 s-1, the viscosity of the gel acid solution remained above 27.8 mPa·s, with a viscosity retention rate of 63.76%. Compared to GLE-1 (uncapsulated), GLE-3 demonstrated improved thermal stability and shear stability after microencapsulation. After 60 min of shearing at 180 °C and shear rate of 170 s-1, the viscosity retention rate was 88.99%. Furthermore, under 180 °C conditions, GLE-3 exhibited good high-temperature slow-release performance compared to GLE-1, which unencapsulated with the same raw materials. By increasing the viscosity of the gel acid, delaying the acid-rock reaction rate, and providing high-temperature slow-release effects, the high-temperature resistance of the acid system was enhanced, ultimately achieving deep acidization in high-temperature reservoirs.

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.