Pickering Emulsion Polymerization Research Articles

Conductivity Enhancement of Poly(3,4-ethylenedioxythiophene)/Lignosulfonate Acid Complexes via Pickering Emulsion Polymerization

Poly(3,4-ethylenedioxythiophene)/lignosulfonate acid (PEDOT/LS) submicron particles are doped into a 3,4-ethylenedioxythiophene (EDOT)/water mixture as a solid stabilizer to form a Pickering emulsion. The conductivity of the new PEDOT/LS complexes prepared by Pickering emulsion polymerization (PEDOT/LS-PEP) is improved by 2 orders of magnitude. The structure and properties of PEDOT/LS-PEP are investigated by UV, FTIR, XRD, XPS, DLS, optical microscope, four point probe meter, and surface resistance tester. The results show that the average particle size increases from 550 nm to 2.4 μm, and the PEDOT content in PEDOT/LS-PEP is 3.5 times that in the original PEDOT/LS submicron particles, while the structure of PEDOT/LS-PEP remains amorphous. Due to the enhancement in conductivity, the coating film made by PEDOT/LS-PEP decreases the surface resistance of glass from 1012 to 106 Ω sq–1. These new PEDOT/LS-PEP complexes meet the requirement of industrial antistatic materials well.

Surfactant-Free Emulsion Polymerization Stabilized by Ultrasmall Superparamagnetic Iron Oxide Particles Using Acrylic Acid or Methacrylic Acid as Auxiliary Comonomers

Iron oxide (IO)-based composite latex particles with a patchy IO overlayer were successfully prepared by Pickering emulsion polymerization of acrylic monomers and/or styrene using acrylic acid or methacrylic acid as auxiliary comonomers. The ultrasmall IO particles adsorbed at the latex surface and played the role of a solid stabilizer. The influence of the synthesis conditions on the composite particle size, polymerization kinetics, IO incorporation efficiency, and particle morphology was studied. Thermogravimetric analysis indicated that the efficiency of iron oxide incorporation was improved with increasing the suspension pH, the amount of auxiliary comonomer, or the IO content and reached ca. 90% under optimized conditions. Reducing the initial iron oxide concentration at constant monomer concentration led to an increased particle size and a reduced colloid stability, indicating that the magnetic nanoparticles stabilized the colloidal nanocomposites. Transmission electron microscopy studies confirmed ...

Selective separation of bifenthrin by pH-sensitive/magnetic molecularly imprinted polymers prepared by pickering emulsion polymerization

Via Pickering emulsion polymerization, pH-sensitive magnetic molecularly imprinted polymers (HM-MIPs) were synthesized using bifenthrin (BF) as the template molecule, and pH-sensitive monomer methacrylic acid as the functional monomer. Characterizations of HM-MIPs were achieved by FTIR, TGA, TEM, SEM, and VSM, and the results indicated that HM-MIPs exhibited magnetic property (Ms=1.06 emu/g). HM-MIPs were acted as the adsorbent for a series of adsorption performance testing of BF. Equilibrium data were described by the Langmuir and Freundlich isotherm models. Kinetic properties were successfully investigated by pseudo-first-order model, pseudo-second-order model. The selective recognition experiments exhibited outstanding selectively adsorption effect of the HM-MIPs for target BF over diethyl phthalate and fenvalerate. In water, the HM-MIPs could achieve the adsorption and release of BF by controlling the pH value of the aqueous solution. The results indicated that the molecularly imprinted polymers exhibited good adsorption, selectivity and pH-sensitive performance for BF.

“Soft” polymer latexes stabilized by a mixture of zinc oxide nanoparticles and polymerizable surfactants: Binders for pigment printing

Abstract “Soft” polymer latexes were synthesized by Pickering emulsion polymerization. O/W emulsions were prepared using monomers as oil phase, and a mixture of zinc oxide nanoparticles and polymerizable surfactants ammonium allyloxtmethylate nonylphenol ethoxylates sulfate (DNS-86) as stabilizers, and then the “soft” polymer latexes were prepared by free radical copolymerization of monomers in oil phase of the O/W emulsions. Stabilities of both the O/W emulsions and the polymer latexes with an increase of DNS-86 were discussed. Effect of the dosages of DNS-86 on water resistance of the polymer films was reported. The polymer latex was applied as a binder for pigment printing of cotton fabrics. The emulsion droplets became smaller, the drop sizes became more homogeneous, and the gel contents of the polymer latexes decreased to almost constant with an increase of the DNS-86 concentration. TEM showed that some zinc oxide nanoparticles were located at the surface of the polymer particles. DNS-86 was conducive to improve water resistance of the polymer films. Fabric printed with the prepared polymer latex had smaller color difference, improved color fastness and excellent ultraviolet radiation shielding performance in comparison with that printed with commercial binder. However, hand feel of the cotton fabrics printed using the synthetic latex was reduced compared with that of the cotton fabrics printed using commercial binder.

Water expandable polystyrene containing cellulose nanofibrils: Expansion behavior and morphology

Here, we reported a new type of water expandable polystyrene (WEPS) beads containing cellulose nanofibrils (CNFs). This expansible material, called CNFWEPS, showed the highest expansion ratio (~16) for the as-synthesized beads and ~8 after 4.5 months, which has never been reported in the literature. Expandable beads containing 9–13wt% of the well-dispersed water were synthesized through Pickering emulsion polymerization of styrene in the presence of CNF. During the polymerization, CNFs rearrange and create nanospheres which entrap water inside polystyrene beads. Morphological investigations along with thermogravimetric analysis showed that the entrapped water is either discrete water droplets of 9–10µm in diameter or bound water with a strong adsorption to the hydrophilic nanoparticles inside the beads. Importantly, the bound water could be preserved several months after synthesis and therefore prolong the shelf-life of the CNFWEPS beads. The analysis of the expansion kinetics of the CNFWEPS beads revealed three-regime behavior with strong temperature dependency. The highest expansion ratio was obtained at 135°C for the sample containing 0.2wt% of CNF. Overall, apart from stabilization of water in the beads, the vital role of CNF unveiled to be reinforcing the foam structure and inhibiting the cell wall rupture by increasing melt strength of the matrix during expansion.

Fabrication of magnetic imprinted sorbents prepared by Pickering emulsion polymerization for adsorption of erythromycin from aqueous solution

In this work, erythromycin-based (EM-based) magnetic molecularly imprinted polymers (MMIPs) were prepared by magnetic eggshells-stabilized Pickering emulsion imprinting polymerization. The feature of easy separation caused by good magnetism made the product separation and adsorption process more time-saving and convenient. More importantly and interestingly, the magnetic eggshell particles were not prepared beforehand, but were found to form instantly and spontaneously in water phase. The magnetic eggshell particles created in this way were used as stabilizers of emulsion polymerization for the first time, which may be benefit for the preservation of magnetism of MMIPs. The imprinting process was conducted by radical polymerization and the MMIPs was characterize by various characterization methods such as Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM) and vibrating sample magnetometer (VSM). The results sufficiently demonstrated the formation of the approximately spherical and wrinkled magnetic imprinted polymers. A series of adsorption experiments showed that the as-prepared MMIPs exhibited not only outstanding adsorption capacities, but also excellent selective adsorption effect toward EM molecules, and the adsorption mechanism were also discussed in detail with different adsorption models.

Encapsulating 8-hydroxyquinoline in graphene oxide-stabilized polystyrene containers and its anticorrosion performance

We report the formation of encapsulated graphene oxide/polystyrene (GO/PS) containers via Pickering emulsion polymerization of oil-in-water emulsions stabilized by GO sheets. Without further functionalization, the as-synthesized GO sheets were used for emulsion stabilization to minimize the process step. A one-step process was developed to encapsulate 8-Hydroxyquinoline (8-HQ) in GO/PS containers. FT-IR study confirmed the encapsulation. The inhibiting effect of 8-HQ was found to affect the kinetics of the emulsion polymerization and shift the polymerization temperature to a higher value. A detailed study of stability, size, and morphology of encapsulated containers (PS/GO) was carried out as a function of GO-to-oil ratio and oil volume fraction in the formulation, to optimize the process parameters. A possible mechanism for the formation of GO/PS containers at various GO-to-oil ratios was discussed. The corrosion inhibition performance of 8-HQ-encapsulated containers was studied in an epoxy coating. These encapsulated containers induced long-term anticorrosive property to the coating. The use of cost-effective materials and a scalable method used in this work can be utilized to prepare environmentally friendly coatings for large-area applications.

Molecularly Imprinted Polymers: Novel Discovery for Drug Delivery.

Molecularly imprinted polymers (MIP) are novel carriers synthesized by imprinting of a template over a polymer. This paper presents the recent application of MIP for diagnostic and therapeutic drug delivery. MIP owing to their 3D polymeric structures and due to bond formation with the template serves as a reservoir of active causing stimuli sensitive, enantioselective, targetted and/or controlled release. The review elaborates about key factors for optimization of MIP, controlled release by MIP for various administration routes various forms like patches, contact lenses, nanowires along with illustrations. To overcome the limitation of organic solvent usage causing increased cost, water compatible MIP and use of supercritical fluid technology for molecular imprinting were developed. Novel methods for developing water compatible MIP like pickering emulsion polymerization, co-precipitation method, cyclodextrin imprinting, surface grafting, controlled/living radical chain polymerization methods are described with illustration in this review. Various protein imprinting methods like bulk, epitope and surface imprinting are described along with illustrations. Further, application of MIP in microdevices as biomimetic sensing element for personalized therapy is elaborated. Although development and application of MIP in drug delivery is still at its infancy, constant efforts of researchers will lead to a novel intelligent drug delivery with commercial value. Efforts should be directed in developing solid oral dosage forms consisting of MIP for therapeutic protein and peptide delivery and targeted release of potent drugs addressing life threatening disease like cancer. Amalgamation of bio-engineering and pharmaceutical techniques can make these future prospects into reality.

Investigation of Four Different Laponite Clays as Stabilizers in Pickering Emulsion Polymerization.

Clay-armored polymer particles were prepared by emulsion polymerization in the presence of Laponite platelets that adsorb at the surface of latex particles and act as stabilizers during the course of the polymerization. While Laponite RDS clay platelets are most often used, the choice of the type of clay still remains an open issue that is addressed in the present article. Four different grades of Laponite were investigated as stabilizers in the emulsion polymerization of styrene. First, the adsorption isotherms of the clays, on preformed polystyrene particles, were determined by ICP-AES analysis of the residual clay in the aqueous phase. Adsorption of clay depended on the type of clay at low concentrations corresponding to adsorption as a monolayer. Adsorption of clay particles as multilayers was observed for all the grades above a certain concentration under the considered ionic strength (mainly due to the initiator ionic species). The stabilization efficiency of these clays was investigated during the polymerization reaction (free of any other stabilizer). The clays did not have the same effect on stabilization, which was related to differences in their compositions and in their adsorption isotherms. The different grades led to different polymer particles sizes and therefore to different polymerization reaction rates. Laponite RDS and S482 gave similar results, ensuring the best stabilization efficiency and the fastest reaction rate; the number of particles increased as the clay concentration increased. Stabilization with Laponite XLS gave the same particles size and number as the latter two clays at low clay concentrations, but it reached an upper limit in the number of nucleated polymer particles at higher concentrations indicating a decrease of stabilization efficiency at high concentrations. Laponite JS did not ensure a sufficient stability of the polymer particles, as the polymerization results were comparable to a stabilizer-free polymerization system.

Polystyrene/graphene oxide nanocomposites synthesized via Pickering polymerization

Abstract The synthesis of graphene oxide (GO)—based nanocomposite materials, as environment-friendly nanostructures suitable for novel applications, has received significant attention in recent years. In this paper, a series of GO have been successfully fabricated utilizing the modified Hummers’ method. GO was characterized by Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy (RS), X-ray diffraction analysis (XRD), Transmission Electron Microscope (TEM) and Scanning Electron Microscope (SEM) respectively. The characterization results showed that GO nanosheets have hydrophilic oxygen-containing functional groups and were well exfoliated. The graphene oxide/polystyrene (PSt) nanocomposite emulsion was synthesized via Pickering emulsion polymerization in the presence of GO nanosheets as a sole emulsifier. TEM, SEM and XRD results all suggested the successful preparation of GO-stabilized PSt colloidal particles. The Pickering emulsion products showed that the average diameter of nanocomposite particles can be well controlled from 240 to 320 nm by variation of the GO content. The GO layer was wrapped on the surface of PSt microspheres. PSt/GO nanocomposites have higher crystallinity and better thermal stability than pure PSt. Graphene oxide was not only being used as an effective solid stabilizer for Pickering emulsion, but also dispersed homogeneously into the production of polystyrene as highly effective nanofiller.

Preparation of dummy-imprinted polymers by Pickering emulsion polymerization for the selective determination of seven bisphenols from sediment samples.

The dummy molecularly imprinted polymers were prepared by Pickering emulsion polymerization. 4,4'-(1-Phenylethylidene) bisphenol was selected as the dummy template to avoid the leakage of the target bisphenols. The microsphere particles were characterized by scanning electron microscopy and nitrogen adsorption-desorption measurements, demonstrating that the regular-shaped and medium-sized particles (40-70μm) were obtained with a specific surface area of 355.759m(2) /g and a total pore volume of 0.561cm(3) /g. The molecular imprinting properties of the particles were evaluated by static adsorption and chromatographic evaluation experiments. The association constant and maximum adsorption amount of bisphenol A were 0.115mmol/L and 3.327μmol/g using Scatchard analysis. The microsphere particles were then used as a solid-phase extraction sorbent for selective extraction of seven bisphenols. The method of dummy molecularly imprinted solid-phase extraction coupled with high-performance liquid chromatography and diode array detection was successfully established for the extraction and determination of seven bisphenols from environmental sediment samples with method detection limits of 0.6-1.1ng/g. Good recoveries (75.5-105.2%) for sediment samples at two spiking levels (500 and 250ng/g) and reproducibility (RSDs < 7.7%, n = 3) were obtained.

Pickering emulsion polymerization kinetics of styrene: Comparison of bare and surface modified SiO2 nanoparticles

ABSTRACTA step towards the understanding of some mechanistic events occurring in the styrene Pickering emulsions, using a SiO2 dispersion, is presented. Polymerizations at 80°C with different levels of a water soluble initiator were performed. The emulsion polymer content was ca. 15% with conversions close to 90%. With conversion and particle size measurements, the particle density was estimated for bare and surface modified SiO2 particles. Then, the average number of radicals per particle was inferred, yielding a pseudo-bulk type polymerization. It was found that bare SiO2 nanoparticles do not participate in the nucleation mechanism; however, they, along with the initiator, promote an enhanced oligomer coagulation. On the other hand, the hexadecyltrimethylammonium bromide modified SiO2 nanoparticles do participate in the nucleation and coagulation mechanisms, yielding more stable and smaller poorly-covered polymer particles. This approach allowed untangling some events such as: particle nucleation, radical entry to particles, particle density, coagulation and vitreous and Trommsdorff effects.

Preparation of l-phenylalanine-imprinted solid-phase extraction sorbent by Pickering emulsion polymerization and the selective enrichment of l-phenylalanine from human urine.

A novel l-phenylalanine molecularly imprinted solid-phase extraction sorbent was synthesized by the combination of Pickering emulsion polymerization and ion-pair dummy template imprinting. Compared to other polymerization methods, the molecularly imprinted polymers thus prepared exhibit a high specific surface, large pore diameter, and appropriate particle size. The key parameters for solid-phase extraction were optimized, and the result indicated that the molecularly imprinted polymer thus prepared exhibits a good recovery of 98.9% for l-phenylalanine. Under the optimized conditions of the procedure, an analytical method for l-phenylalanine was well established. By comparing the performance of the molecularly imprinted polymer and a commercial reverse-phase silica gel, the obtained molecularly imprinted polymer as an solid-phase extraction sorbent is more suitable, exhibiting high precision (relative standard deviation 3.2%, n = 4) and a low limit of detection (60.0 ± 1.9 nmol·L(-1) ) for the isolation of l-phenylalanine. Based on these results, the combination of the Pickering emulsion polymerization and ion-pair dummy template imprinting is effective for preparing selective solid-phase extraction sorbents for the separation of amino acids and organic acids from complex biological samples.

Molecularly imprinted polymer microspheres derived from pickering emulsions polymerization in determination of di(2‐ethylhexyl) phthalate in bottled water samples

ABSTRACTThe mono‐dispersed macroporous Molecularly Imprinted microspheres (MIPMs) selective for Diethylhexyl Phthalate (DEHP) were synthesized by Pickering emulsion polymerization. Silica nanoparticles were stabilizers in forming a stable oil‐in‐water emulsion, while the polymeric system was prepared by radical polymerization using methacrylic acid as functional monomer and ethylene glycol dimethacrylate as cross‐linker. The results of scanning electron microscopy and nitrogen adsorption desorption measurement indicated that the obtained polymer microspheres had regularly porous structure and narrowly diameter distribution (100 nm), besides the specific surface area (SBET) was 452 m2 g−1, pore volume was 9.685 cm3 g−1, and pore diameter was 5.089 nm. The equilibrium adsorption capacity of MIPs was 1.75 mg g−1 at 298 K. Good selectivity for DEHP in another two kinds of analogies (DBP and DAP) was demonstrated with high selectivity coefficients, respectively 17.753 and 19.450. In the end, DEHP‐MIP was used as packing of solid‐phase extraction to form an sensitive analytical method in extraction and enrichment DEHP in bottled water samples with the limits of detection of 1.7–2.5 μg L−1.The recoveries at three spiking level (0.05, 0.1, and 1 mg L−1) were varied between at 97.5 and 103.1% with RSD values below 3.5. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43484.

Pickering Emulsion Polymerization of Styrene using Nano-SiO2 and Subsequent Use of the Produced Core–Shell Structures as Fillers for Ethylene Vinyl Acetate Copolymer and Polypropylene

ABSTRACTSolid particles can stabilize emulsions instead of conventional surfactants. Emulsion polymerization of styrene, as an example of polymerizable oil, was processed in the present work after ultrasonication of styrene in water in the presence of silica nanoparticles as stabilizer. Field emission scanning electron microscopy, equipped with energy-dispersive X-ray unit, and transmission electron microscopy confirmed the formation of polystyrene particles covered by a sheath of self-assembled silica. Addition of these hybrids in different loadings (2–14 wt%) to polypropylene and ethylene vinyl acetate copolymer could improve their tensile strength and hardness. The mechanical enrichment could be attributed to the action of the silica shell layer to delay the phase separation process encountered between the polystyrene from one side and polypropylene/ethylene vinyl acetate from other side, which translates into different extents of reinforcements.

Controlled release behavior of pH-sensitive poly(2-(diethylamino)ethyl methacrylate)/palygorskite composite microspheres prepared via pickering emulsion polymerization

(11.64 mM s) and GON-AN-FA (10.83 mM s) is much larger than that of the traditional positive MRI contrast agents, such as Magnevist (4.7 mM s). The results of cell viability assays indicate that the GON-AN and GON-AN-FA are almost non-cytotoxic. Furthermore, the specificities of GON-AN and GON-AN-FA were evaluated with two kinds of cancer cells that overexpress folate receptor alpha (FRα). The results reinforce that the GON-AN-FA is high-specifically-targetable to cancer cells via recognition of ligand FA and receptor FRα. In addition, the TEM and DLS results indicate that the SPION-AN-FA has a spherical shape, a uniform size and an excellent water-dispersibility (PDI b 0.05). The results of LSCM and flow cytometry demonstrate that the SPION-AN-FA is highly specific to MCF-7 and SPC-A1 cells due to the recognition of ligand FA and receptor FRα. The r1/r2 value of SPION-AN-FA is around 40, which is much higher than that of Resovist® indicating that our SPION-AN-FA has a stronger T2 shortening effect. The T2weighted images of MCF-7 cells incubated with SPION-AN-FA are significantly darker than those of MCF-7 cells incubated with AN, indicating that our SPION-AN-FA has a strong MR imaging efficacy.

Fabrication of zinc–histidine-functionalized graphene quantum dot framework amphiphilic nanoparticles and application in the synthesis of polystyrene microspheres for adsorption of Cu2+ by Pickering emulsion polymerization

We reported fabrication of zinc–histidine-functionalized graphene quantum dot framework amphiphilic nanoparticles and application in the synthesis of polystyrene microspheres for adsorption of Cu2+ by Pickering emulsion polymerization.

Graphene oxide as a sacrificial material for fabricating molecularly imprinted polymers via Pickering emulsion polymerization

Graphene oxide (GO) was introduced as a sacrificial material, for the first time, to fabricate a hollow molecularly imprinted polymer (HMIP)viaPickering emulsion polymerization.

Molecularly imprinted polymer prepared by Pickering emulsion polymerization for removal of acephate residues from contaminated waters

ABSTRACTA molecularly imprinted polymer (MIP) prepared with Pickering emulsion polymerization was designed by a computational approach for removal of acephate from aqueous solution. Methacrylic acid, ethylene glycol dimethacrylate, and chloroform were screened as the optimal functional monomer, crosslinker, and porogen by the Gaussian 03 package using the density functional theory method. The polymerization was carried out in an oil‐in‐water emulsion using nano‐SiO2 particles as stabilizer instead of a toxic surfactant. The characterization results indicated that the prepared MIP had a porous and hollow core, and the particle size was approximately 20 μm. The binding and recognition abilities of MIP for acephate were studied through equilibrium adsorption analysis and selectivity analysis. The results showed that the MIP had high binding capacity and excellent selectivity for acephate. The saturated binding amount could reach 6.59 × 103 μg/g. The Langmuir isotherm model gave a good fit to the experimental data. Moreover, the results of a reusability analysis and practical application suggested that the prepared MIP provides the potential for removal of acephate residues from aqueous solution. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43126.

Partitioning of Laponite Clay Platelets in Pickering Emulsion Polymerization.

Partitioning of laponite disklike clay platelets between polymer particles and bulk aqueous phase was investigated in Pickering surfactant-free emulsion polymerization of styrene. Adsorption of laponite clay platelets plays an important role in the stabilization of this system, influencing the particle size and the number of particles, and, hence, the reaction rate. Adsorption isotherms show that, while the laponite clay platelets are almost fully exfoliated in water, they form multilayers on the surface of the polymer particles by the end of polymerization, as confirmed by transmission electron microscopy (TEM). This observation is supported by quartz crystal microbalance, conductivity, and TEM measurements, which reveal interactions between the clay and polystyrene, as a function of the ionic strength. The strong adsorption of clay platelets leaves a low residual concentration in the aqueous phase that cannot cause further nucleation of polymer particles, as demonstrated during seeded emulsion polymerization experiments in the presence of a high excess of clay. A Brunauer-Emmett-Teller (BET)-type model for laponite adsorption on polystyrene particles matches the adsorption isotherms.