Inverse Emulsion Polymerization Method Research Articles

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.

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.

Chitosan-based composite microspheres for treatment of hexavalent chromium and EBBR from aqueous solution

Hexavalent chromium is widely used in industrial fields, but its pollution has posed a great threat to the environment due to its high toxicity. We created a chitosan-based microsphere biosorbent (CP) by combining polyethyleneimine with chitosan adopting inverse emulsion polymerization method. Under the optimal conditions (pH = 3), the maximum adsorption capacity of composite microspheres can reach 299.89 mg g−1, which is much higher than that of chitosan microspheres (168.91 mg g−1). When the amount of CP is 0.25 g L−1, the removal rate of 50 mg L−1 Cr(VI) and 50 mg L−1 Eriochrome blue-black R (EBBR) can reach 95% and 99%, respectively. The time required for CP to reach adsorption equilibrium (180 min) was significantly shorter than that of chitosan microspheres (540 min), and the adsorption rate was significantly improved. Langmuir isotherm model, pseudo-second-order kinetic model and thermodynamic calculation results penetrated an endothermic spontaneous, monolayer, and chemical adsorption process. Biomass composite microspheres CP has obvious selectivity and the adsorption capacity retention rate of CP was still 71.32% after four adsorption cycles. This work proposed an easily prepared and biomass-based microspheres for the effective removal of Cr(VI) in printing and dyeing wastewater pollution through adsorption.

A facile imine-linked covalent organic framework doped with a carbon dot composite for the detection and removal of Hg2+ in surface water.

Hg2+ is one of the most toxic chemical species in the water environment, and thus developing a new fluorescent covalent organic framework for both the detection and removal of Hg2+ is highly desirable. Herein, a fluorescent composite, termed TpPa-1 COF@CDs, was synthesized by inverse emulsion polymerization method using an imine covalent organic framework as the supporting material and carbon dots as the fluorescent sensor element. The crystallinity, porosity, rich functional receptors (hydroxyl and amino groups), thermal stability and fluorescent properties of TpPa-1 COF@CDs were characterized. The results showed that TpPa-1 COF@CDs exhibited a good detection and removal performance for Hg2+, which was evidenced by its high sensitivity (LOD = 0.75 μg L−1), superior selectivity, large adsorption capacity (235 mg g−1), fast adsorption rate (30 min equilibrium time) and good regeneration (at least five cycles). More importantly, the simple functional monomer, short reaction time and metal-free raw material made TpPa-1 COF@CDs reliable, cost effective and eco-friendly. This research demonstrated the facile construction of a functional covalent organic framework composite for water environmental remediation technologies of metal pollution.

Polysaccharide-Based Lotus Seedpod Surface-Like Porous Microsphere as an Efficient Drug Carrier for Cancer Treatment.

BackgroundThis study aimed to evaluate the properties and functions of polysaccharide-based porous microsphere (PPM) for drug delivery, as well as its inhibitory effect on malignant tumors.Materials and MethodsPPM was prepared using the inverse emulsion polymerization method. FT-IR measurements were conducted to measure the wavenumber of PPM. Particle size distribution was tested with a particle analyzer, and surface morphologies of PPM were observed using a scanning electron microscope (SEM). Dialysis method, Cell Counting Kit-8 (CCK-8), and cell apoptosis analysis were adopted to evaluate the drug release, cytotoxicity and biocompatibility of mitomycin-C (MMC), respectively. Finally, an in vivo study was performed in C57BL/6 mice to confirm the function of MMC-loaded PPM on tumor growth.ResultsFT-IR spectra proved the successful preparation of MMC-loaded PPM. PPM had an average size of 25.90 ± 0.34 μm and then increased to 30.10 ± 0.20 μm after drug loading. Under SEM, the surface morphology was lotus seedpod surface-like, with macropits on the surface and micropores in macropits. Compared with the free MMC group, MMC-loaded PPM exhibited a delayed drug release rate in a pH-dependent manner and higher cell viability. Flow cytometry results showed that the cell apoptosis in the PPM/MMC group was lower than that in the free MMC group. In vivo experiment revealed the inhibitory efficacy of MMC-loaded PPM on malignant tumors.ConclusionIn summary, MMC-loaded PPM exhibited favorable surface morphology, sustained drug release ability, nontoxicity and excellent biocompatibility, suggesting that PPM might be a potential drug carrier for tumor treatment.

PNIPAAM/SA pH-responsive microcapsules based on chemical and non-covalent crosslinking

Abstract A triple interpenetrating polymer network (IPN) with dual responses to temperature and pH was constructed based on chemical crosslinking and electrostatic interaction. In this IPN, CaCO3 microspheres were used as the kernel and PNIPAAM/sodium alginate microcapsules were prepared by the inverse emulsion polymerization method. Research results demonstrated that CaCO3 kernels were decomposed into Ca2+ and CO2 at pH 1.2. Such decomposition facilitated the formation of triple IPN of Ca2+ crosslinking. Moreover, microcapsules were expanded by tension of CO2 and the volume increased to 3.55 × 105 times that of the original microcapsules, with capsules remaining an intact morphology. These microcapsules loading doxorubicin hydrochloride (DOX) stability and responses to environment were investigated. No drug overflow was observed at pH 7.4, indicating the high stability of microcapsules. However, DOX was released gradually in the simulated human stomach acid with a weak solution of hydrochloric acid (pH 1.2, 37 °C). This showed that the prepared microcapsules were feasible for drug-loaded capsules and the controlled drug release behavior could relieve side effects of drugs to human body. Moreover, it will help to increase the drug utilization and realize accurate treatment.

Application of Modified PANI-ZnO Composites for NH3Gas Sensor at Ambient Temperature

Polyaniline and zinc oxide nanoparticles were successfully synthesized through inverse emulsion polymerization method and hydrothermal method respectively. For ammonia gas sensing using LCR meter thin film of the composite was fabricated by using spin coater. The functional groups, morphological, optical, structural properties of zinc oxide nanoparticles, polyaniline (emeraldine salt) and composites were investigated by FTIR spectroscopy, Scanning electron microscopy (SEM), UV- Visible spectroscopy and XRD analysis. The formation of ZnO particles of different shapes in the nano range was confirmed from UV-visible and XRD analysis. UV visible spectrum shows the formation of nanoparticles of ZnO. Thin film of Polyaniline/zinc oxide composites were deposited on the surface of copper interdigitated electrode. The fabricated device showed sensitivity to ammonia gas (NH3) at ambient temperature (300 K). It was observed that the resistance is decreases with the increase of volume of ammonia gas. The electrical properties were also investigated of the different concentration of nanocomposite. Optimum sensing response was achieved with PANI in the presence of 50 wt% ZnO nanoparticles. It may also be inferred from this study that the solution mixing process to produce composites has promising future if handled carefully.

Application of Modified PANI-ZnO Composites for NH3Gas Sensor at Ambient Temperature

Polyaniline and zinc oxide nanoparticles were successfully synthesized through inverse emulsion polymerization method and hydrothermal method respectively. For ammonia gas sensing using LCR meter thin film of the composite was fabricated by using spin coater. The functional groups, morphological, optical, structural properties of zinc oxide nanoparticles, polyaniline (emeraldine salt) and composites were investigated by FTIR spectroscopy, Scanning electron microscopy (SEM), UV- Visible spectroscopy and XRD analysis. The formation of ZnO particles of different shapes in the nano range was confirmed from UV-visible and XRD analysis. UV visible spectrum shows the formation of nanoparticles of ZnO. Thin film of Polyaniline/zinc oxide composites were deposited on the surface of copper interdigitated electrode. The fabricated device showed sensitivity to ammonia gas (NH3) at ambient temperature (300 K). It was observed that the resistance is decreases with the increase of volume of ammonia gas. The electrical properties were also investigated of the different concentration of nanocomposite. Optimum sensing response was achieved with PANI in the presence of 50 wt% ZnO nanoparticles. It may also be inferred from this study that the solution mixing process to produce composites has promising future if handled carefully.

Preparation and characterization of polymer microcapsules containing ammonium persulfate with controlled burst release

Microcapsules containing water-soluble ammonium persulfate (APS) cores as gel breakers that offer controlled burst release, are become increasingly important in improving the gel breaking efficiency of fracturing fluids in oil fields. To date, microcapsules with various control slow release behaviors have been thoroughly investigated, but microcapsules with burst release properties are rarely studied. Here, we reported a novel inverse emulsion polymerization method to exploit this new type of microcapsule. The microcapsules were composed of APS cores and stimuli-responsive P(MMA-co-AA) copolymer shells. The microcapsules have spherical structures with diameters of 10 to 16 μm. The encapsulated cores offer controlled burst release from the microcapsules and their beginning time of burst release could be delayed up to 42 h. Moreover, all of the cores could be completely released within 1 h from the microcapsules. The temperature, pH, and salt concentration change could stimulate the release. These novel microcapsules might have promising applications in oil exploration, batteries, monomer polymerization, fiber printing, and grease.

Synthesis of cationic polyacrylamide via inverse emulsion polymerization method for the application in water treatment

In order to improve the flocculent efficiency of wastewater treatment, a cationic flocculant poly (acrylamide-[2-(methacryloyloxy) ethyl] trimethyl ammonium chloride) (P (AM-DMC)) (CPAM) has been synthesized successfully via an inverse emulsion polymerization. Acrylamide (AM) and [2-(methacryloyloxy) ethyl] trimethyl ammonium chloride (DMC) were served as monomers. The molecular structure of CPAM was characterized by Fourier transform infrared spectra (FT-IR) and 1H nuclear magnetic resonance spectrum (1H-NMR). The morphology of CPAM particles has been investigated by transmission electron microscope (TEM). Results showed that CPAM was the copolymer of AM and DMC and the particles of CPAM were uniform spheres (the size was about 200 nm). The synthetic conditions of CPAM have been studied and optimized by single-factor experiments. An optimized product was obtained at an intrinsic viscosity of 560 mL/g with a total monomer concentration of 25% and initiator concentration V50 of 0.2% (based on the total monomer mass). The amount of emulsion was 6% and the HLB (Hydrophile-Lipophile-Balance) of emulsion was 7.3. In addition, the flocculation property of CPAM was evaluated with kaolin suspension using jar test, and the result demonstrated that the flocculation property of CPAM performed better than kaolin flocculation.

Novel microreactors of polyacrylamide (PAM)[sbnd]CdS microgels for admirable photocatalytic H2 production under visible light

Cadmium sulfide, with its narrow band gap, can be used as a photocatalyst in the visible light region for the splitting of water, but its limited number of active sites and tendency to agglomerate are problematic for producing high yields of hydrogen. Therefore, an inverse emulsion polymerization method was used to fabricate polyacrylamide (PAM) microgels as a substrate to immobilize CdS nanoparticles (PAM-CdS). The PAM microgels not only immobilized the CdS nanoparticles, but also prevented aggregation. NCd bonds in the PAM-CdS microgels facilitated electron transfer from the PAM to the CdS resulting in more electrons participating in the H2 production process. The electrostatic interactions between the PAM and CdS also hindered the recombination of electron-hole pairs. These PAM-CdS microgels exhibit admirable photocatalytic H2 production performance with a H2 production rate of up to 5.21 mmol h−1 g−1.

Polyaniline@CuNi nanocomposite: A highly selective, stable and efficient electrode material for binder free non-enzymatic glucose sensor

We present an efficient, highly selective and binder free non-enzymatic glucose sensor based on polyaniline@copper-nickel (PANI@CuNi) nanocomposite. PANI@CuNi nanocomposites with different loading ratio of nanoparticles (1: 025, 1: 0.33, 1: 05 and 1: 1) were prepared by mixing solution of PANI, synthesized through inverse emulsion polymerization method, and CuNi nanoparticles, synthesized through polyol process. The as prepared PANI@CuNi nanocomposites were coated on glassy carbon substrate without binder for non-enzymatic glucose sensing. A considerable increase in the active surface area of the electrode occurred after coating of this material. Electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV) and chronoamperometry demonstrated that PANI@CuNi nanocomposite with 1: 0.5 ratio could be a good choice to be used as electrode material for non-enzymatic glucose sensing. The PANI@CuNi modified electrode exhibited high sensitivity (1030 μA mM−1 cm−2), good lower detection limit (0.2 μM) and a linear range of 5.6 mM (R2 = 0.992) with additional advantage of excellent selectivity, high stability and effective detection in real blood samples.

Nano-Armoring of Enzymes: Rational Design of Polymer-Wrapped Enzymes.

The formulation in which therapeutic proteins are administered plays a key role in retaining their biological activity. Enzyme wrapping, using synthetic polymers, is a strategy employed to provide enzymes with lower immunogenicity, longer circulation times, and better targeting capabilities. Protein-polymer complexation methods, involving covalent, noncovalent, and electrostatic interactions, that can provide means to develop formulations for retaining enzyme stability are discussed in this chapter. Amphiphilic self-cross-linkable polymer was used to encapsulate capsase-3 enzyme in the nanogel, while inverse emulsion polymerization method was used to entrap α-glucosidase enzyme in the nanogel. These nanogels were characterized by dynamic light scattering, transmission electron microscopy, and gel electrophoresis. Upon release of caspase-3 enzyme from polymeric nanogel, it retained nearly 86% of its original activity. Similarly, α-glucosidase that was encased in the acid cleavable polymeric nanogel exhibited substantial activity after release under acidic conditions (pH 5, 48h). Nano-armoring of the enzymes were nearly complete and provided high yields of the encased enzyme.

Selective adsorption behavior of Cd(II) ion imprinted polymers synthesized by microwave-assisted inverse emulsion polymerization: Adsorption performance and mechanism

Microwave-assisted inverse emulsion polymerization method was used to prepare Cd(II) imprinted polymer (IIP) by using β-cyclodextrin (β-CD) and acrylamide (AM) as functional monomer, epichlorohydrin (ECH) as crossing-linking agent, ammonium persulfate as initiator. The Cd(II) imprinted polymer was characterized by SEM, FTIR and TGA. The influences of initial concentration of Cd(II), pH values, temperature, time and competitive ions on adsorption capacity and recognition properties are investigated. Under the optimal conditions, the adsorption capacity could reach 107mg/g. Furthermore, pseudo first order kinetic model, pseudo second order kinetic model and intra-particular diffusion model were used to describe the adsorption kinetic behavior. Results showed that the pseudo-second-order model (R2 0.9928–0.9961) had the best agreement with the experimental data. Langmuir adsorption isotherm model described the experimental data well, which indicated that adsorption was mainly monolayer absorption. Moreover, the study of adsorption thermodynamics (ΔG0<0, ΔH0>0, ΔS0>0) suggested that the adsorption process was a spontaneous and endothermic process. Competitive selectivity experiment revealed that imprinted polymer could selectively recognize Cd(II). It provides a new idea for removing Cd(II) from aqueous solution.

Enhanced ionic conductivity and electrochemical capacity of lithium ion battery based on PVDF-HFP/HDPE membrane

Poly(vinylidene fluoride-co-hexafluoropropylene)/high density polyethylene (PVDF-HFP/HDPE) membrane with enhanced ionic conductivity and electrochemical capacity for lithium ion battery application has been successfully prepared by non-solvent induced phase separation (NIPS) technique. HDPE particles with size smaller than 250nm is achieved via optimized inverse emulsion polymerization method. Results indicate that the novel PVDF-HFP/HDPE membrane has ion conductivity of 2.97mScm−1 at 25°C, higher than that 1.92mScm−1 of pristine PVDF-HFP membrane. Additionally, the LiCoO2/Li cells assembled with PVDF-HFP/HDPE membrane show good C-rate and cycling performance which is parallel to the commercial PP membrane.

Calculation of particle size distribution of polyaniline salts using imagej

The detailed analysis of particle size distribution is desirable in several technical fields that ma-nipulate granular/particulate materials including size reduction. This article describes the mani-pulation of scanning electron micrographs (SEM) of polyaniline (PANI) salts using ImageJ soft-ware. The PANI salts were prepared by two servable methods i.e. emulsion polymerizations and inverse emulsion polymerizations. 1,2 The effects of these synthesis routs on the particles shape and size distributions of the PANI salts were evaluated. Slight differences in the particle shapes were observed for these PANI salts. The polymer synthesized by inverse emulsion polymerization method showed smaller size than the one prepared by emulsion polymerization method. This type of computer based image processing methods provide better solutions to practical measurement and size distribution analysis as compared to the time consuming and vague manual means.

Enhanced adsorption of Pb(II) by Al(OH)3/(PAA-CO-PAM) sub-microspheres with three-dimensional interpenetrating network structure

Abstract Al(OH) 3 /(PAA-CO-PAM) sub-microspheres have been synthesized via inverse emulsion polymerization method using 0.0132 g (NH 4 ) 2 S 2 O 8 as initiator, 2.2 g each of acrylamide aluminum acrylate as monomers, 1.5 g Span-80 and 0.5 g polyoxyethylene octylphenol ether (OP-10) as emulsifiers at 66 °C for 10 h. The composition and morphology of the obtained Al(OH) 3 /(PAA-CO-PAM) sub-microspheres were investigated by infrared spectrum, X-ray powder diffraction (XRD) and scanning electron microscopy. The obtained Al(OH) 3 /(PAA-CO-PAM) sub-microspheres were used to investigate adsorption of Pb(II) from aqueous solutions. The research results display that composite material has high adsorption capacity for Pb(II) at an optimum pH 5. The maximum adsorption capacity was 106.2 mg/g within 240 min at 24 °C. Various thermodynamic parameters such as free energy (Δ G ), enthalpy (Δ H ) and entropy (Δ S ) showed that the adsorption was spontaneous, endothermic and feasible. Adsorption behavior for Pb(II) onto sub-microspheres belongs to the pseudo-second-order kinetic model and the adsorption process is a chemical process.

Synthesis and Characterization of Fluorescent Acrylamide Water Soluble Macromer

Fluorescent acrylamide water soluble macromer was synthesized from dimethylaminopropylmethacrylamide-9-(chloromethyl)anthracene quaternary ammonium salt monomer using an inverse emulsion polymerization method. It was initiated by benzoylperoxide and stabilized by a co-emulsifier system consisting of Span®80 and Tween®60 dispersed in a continuous phase of cyclohexane with HLB value of 6.42. The polymerization was done at 80°C for 4 hours. The obtained macromer exhibited similar functional groups, ultraviolet-visible absorption and fluorescent emission but different solubility when compared to the monomer. Further analyses by proton nuclear magnetic resonance spectroscopy and mass spectrometry revealed the chemical structure of the macromer as a dimer of the monomer containing carcon-carbon double bonds.

Novel strategy for the determination of UCST-like microgels network structure: effect on swelling behavior and rheology

UCST-type interpenetrated and random copolymer microgels of polyacrylamide and poly(acrylic acid) were obtained via inverse emulsion polymerization method. The morphology of the microgels was determined by scanning electron microscopy (SEM) and atomic force microscopy (AFM). Dynamic light scattering was used to study both the swelling behavior as a function of temperature and pH and the particle size distribution of the system. Concerning the structural characterization, a combination of the equilibrium swelling theory (Peppas–Merrill equation) and AFM technique was used to determine the mesh size of microgels. An oscillatory rheometer was used to study the viscoelastic properties. The moduli, G′ and G′′, of the microgel dispersions suggested a solid-like behaviour and structure formation. Scaling theory was applied to describe the structure formation (clustering) and the fractal dimension. The influence of composition and type of microgel, random or interpenetrated, was discussed in the above mentioned properties and behaviors.

UCST-Like Hybrid PAAm-AA/Fe3O4 Microgels. Effect of Fe3O4 Nanoparticles on Morphology, Thermosensitivity and Elasticity

The incorporation of metal oxide nanoparticles into microgels forming hybrid systems gives additional functionalities to the system and widens the field of potential application in biomedicine, biotechnology, and other fields. In particular, there have been very few investigations regarding UCST-like hybrid microgels. In connection with this, we report the preparation of UCST-like hybrid microgels of magnetite nanoparticles (Fe(3)O(4)) encapsulated in poly(acrylamide-acrylic acid) microgel matrix via an inverse emulsion polymerization method. The key factor in the preparation of hybrid microgels is the need to divide in two the aqueous phase of the emulsion and feed them separately in order to avoid the aggregation of magnetic nanoparticles prior to polymerization reaction. The morphology, size, and spherical shape of hybrid microgels are determined by scanning electron microscopy. The encapsulation of magnetite nanoparticles within the polymer matrix is confirmed by transmission electron microscopy. Dynamic light scattering is employed to study both the swelling UCST-like behavior and the surface charge of the hybrid microgels. Swelling measurements confirm that the incorporation of magnetite does not affect the thermosensitivity of the system. In order to highlight the rheological behavior that can affect the final potential applications of these hybrid systems, a deep study of the viscoelastic properties is carried out by means of an oscillatory rheometer. The dependence of G' and G'' of the microgel dispersions with the frequency suggests a gel-like behavior and hence the occurrence of structural organization. In order to understand this structure formation and the influence of the magnetite in the interaction between hybrid microgels, scaling theory was applied. In terms of rheology, the addition of magnetite leads to a change in the interaction between hybrid microgels giving rise to an increase in the elasticity of the system.