Copolymer Emulsifier Research Articles

Synthesis, aggregation behavior of alternating copolymer emulsifier in oil solution and its application in oil-based drilling fluids

In order to solve the emulsification problem of oil-based drilling fluids under high-temperature conditions, the copolymer emulsifier with the structure of alternating tertiary amine moieties and alkyl groups was synthesized by the reaction of N,N-dimethylethylenediamine and the alternating copolymer of maleic anhydride with 1-octadene (PMAO). The structure compositions and molecular weight of copolymer emulsifiers were characterized by FT-IR spectra, 1H NMR spectra, elemental analyse and multi-angle laser light scattering. The influence of tertiary amine moieties proportion in copolymer emulsifier on aggregation, interfacial activity, pH-response and emulsion stability were studied. The abundant presence of tertiary amine makes copolymer stabilize water-in-oil emulsion under neutral and weak alkaline conditions while destabilizing the emulsion under acidic conditions. Combining the above experimental data and the stability of water-in-oil emulsions prepared by the copolymer emulsifier, it was found that the emulsifier which has a high proportion of tertiary amine was indeed better at the performance of salt resistance under high temperature. When the copolymer emulsifier (D100) was used in an oil-based drilling fluid system, the electricity stability is greater than 1000 V and the filtrate volume is only 0.6 mL after aging at 232 °C for 16 h.

CO2-responsive zwitterionic copolymer for effective emulsification and facile demulsification of crude heavy oil

Viscosity reduction by emulsification would greatly facilitate the exploitation and pipelining transportation of heavy oil, as well as oil sands/sludge washing. However, the final demulsification process to achieve separation of oil and water is tricky. Therefore, developing smart emulsifiers that can be switched on demand to achieve both effective emulsification and facile demulsification in subsequent oil/water separation process would be of great significance to the practical applications. In this paper, a zwitterionic copolymer emulsifier comprising acrylamide (AM), 2-(diethylamino)ethyl methacrylate (DEAEMA) and 3-[dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]azaniumyl]propane-1-sulfonate (SBMA) was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization for better control of the molecular weight, exhibiting good salt resistance and fast CO2-responsiveness. The prepared copolymer can efficiently emulsify heavy crude oil with a viscosity reduction rate up to 98.6% in highly mineralized water. While in the presence of CO2, the formed heavy oil/water emulsions can be rapidly broken to obtain oil-water two phases. Compared with traditional demulsification methods, the CO2-responsive strategy presented in this work can achieve a lower oil content in water (1.4%) after separation. Furthermore, the copolymer can also be applied to effectively emulsify and clean oily sludge. The CO2-responsive zwitterionic copolymer emulsifier demonstrated great potential in various engineering applications including exploitation and pipelining transportation of heavy oil, and oil sands/sludge washing, facilitating reduction of water pollution and energy saving.

Study on the Preparation and Anti-CO2 Corrosion Performance of Soap-Free Latex for Oil Well Cement.

To improve the resistance to CO2 corrosion of oil well cement, soap-free emulsion polymerization was used to prepare a soap-free latex (PSAC) with sodium styrene sulfonate (SSS) and nano-SiO2 (SSS/SiO2) as the ionic copolymer emulsifier. The effects of SSS/SiO2 on the performance, thermal stability, and latex particle morphology of the PSAC were investigated through zeta potential, TGA, and TEM measurements, respectively. The carbonation resistance properties of cement with PSAC were evaluated, and the anticorrosion mechanism of the PSAC cement was determined by SEM, EDS, XRD, and 29Si NMR analyses. The results showed that the PSAC particle size was uniform, the particles were monodispersed, and they had a typical core–shell structure and good heat resistance. The carbonation resistance test results showed that after 60 days of corrosion, the corrosion depth of the cement with 12.0% PSAC content was only 2.16 mm, the permeability was 0.0018 mD, and the decrease in the compressive strength was 6.65%. The porosity in the cement was reduced significantly, and the pore volume (>50 nm) of the cement was reduced by 0.24 times. The PSAC film formation decreased the contact between hydration products and CO2. In addition, the nano-SiO2 in the PSAC reacted with Ca(OH)2 to reduce the free Ca(OH)2 content in the cement and generate C–S–H gel with a low Ca/Si ratio and high polymerization, which did not react as readily with CO2.

Hollow SiO2 microspheres with thiol-rich surfaces: The scalable templated fabrication and their application for toxic metal ions adsorption

In this study, the templated fabrication of hollow SiO2 microspheres with thiol-rich surfaces and their application as adsorbents for toxic metal ions were demonstrated. (Cyclohexane + TEOS)-in-water Pickering emulsion was first prepared employing detachable polyurethane-g-poly (N,N-dimethyl acrylamide) (PU-g-PDMA) copolymer micelles as emulsifiers. The subsequent Pickering emulsion interface directing sol-gel reaction of TEOS led to the formation of SiO2 microspheres. Hydrophobic PU cores of PU-g-PDMA copolymer emulsifier micelles were in-situ entrapped in the formed SiO2 layers, while hydrophilic PDMA shells were completely exposed on the surfaces of the SiO2 shells, forming polymer brush-like structure. The subsequent removal of PDMA shells through the cleavage of the reversible disulfide linkages between PU core and PDMA shells left a large number of thiol groups on the surfaces of hollow SiO2 microspheres. The resulting hollow SiO2 microspheres with thiol-rich surfaces, described as SiO2@SH in the text, demonstrated a promising recyclable adsorption for toxic metal ions. ~88% of adsorption capacity for Pb2+ has been maintained after four cycles of adsorption-desorption. The structure of hollow SiO2@SH microspheres was carefully characterized with scanning electron microscope (SEM), transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT-IR) and Raman spectroscopy, respectively.

Polymer nanoparticles with a sensitive CO2‐responsive hydrophilic/hydrophobic surface

ABSTRACTPoly(methyl methacrylate) (PMMA) nanoparticles with a sensitive CO2‐responsive hydrophilic/hydrophobic surface that confers controlled dispersion and aggregation in water were prepared by emulsion polymerization at 50 °C under CO2 bubbling using amphiphilic diblock copolymers of 2‐dimethylaminoethyl methacrylate (DMAEMA) and N‐isopropyl acrylamide (NIPAAm) as an emulsifier. The amphiphilicity of the hydrophobic–hydrophilic diblock copolymer at 50 °C was triggered by CO2 bubbling in water and enabled the copolymer to serve as an emulsifier. The resulting PMMA nanoparticles were spherical, approximately 100 nm in diameter and exhibited sensitive CO2/N2‐responsive dispersion/aggregation in water. Using copolymers with a longer PNIPAAm block length as an emulsifier resulted in smaller particles. A higher concentration of copolymer emulsifier led to particles with a stickier surface. Given its simple preparation and reversible CO2‐triggered amphiphilic behavior, this newly developed block copolymer emulsifier offers a highly efficient route toward the fabrication of sensitive CO2‐stimuli responsive polymeric nanoparticle dispersions. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 2149–2156

Synthesis and performance evaluation of a polymer microsphere based nanosilica as a cementing fluid loss reducer

Polymer microspheres (ZJD-220) comprising styrene, butyl acrylate (BA) and methyl methacrylate (MMA) were prepared by soap-free emulsion polymerisation, utilising 2-acrylamido-2-methyl propane sulfonic acid (AMPS) and sodium p-styrene sulfonate (SSS) as anionic copolymer emulsifiers, and used as a novel temperature-resistant fluid loss reducer for oil well cement. The influence of the anionic copolymer emulsifier on the properties of the polymer microspheres was assessed and the fluid loss performance of cement slurries modified by ZJD-220 was evaluated. The ratio and amount of AMPS and SSS were found to have an obvious influence on the characteristics of the polymer microspheres, whose particle size distribution was uniform and monodisperse. The ZJD-220 had excellent thermal resistance and a typical core–shell structure. The fluid losses of freshwater- and salt-based cement slurries (18% sodium chloride) modified with ZJD-220 were controlled within 43 ml and 75 ml, respectively, when the mass fraction of ZJD-220 was 3·0% of the total mass of cement under an ultra-high temperature of 200°C (bottom-hole circulating temperature). Evaluation of the performance of ZJD-220 mixed into different kinds of cement systems with other additives showed that ZJD-220 has good compatibility with different cement slurry systems and additives. Cement slurry with added ZJD-220 showed excellent ability to control filter loss due to the ‘adsorption, bridge-building, film-filling and plugging’ synergistic reaction of the ZJD-220 filling gaps between cement particles and the filter cake pores.

Reductively Responsive Gel Capsules Prepared Using a Water-Soluble Zwitterionic Block Copolymer Emulsifier.

Utilizing the unique solubility of poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC), which is soluble in only water and alcohol, we synthesized a water-soluble block copolymer emulsifier composed of a hydrophilic PMPC block and an amphiphilic poly[oligo(ethylene glycol) methacrylate] (POEGMA) block via reversible addition-fragmentation chain transfer (RAFT) polymerization. Water-in-oil (W/O) emulsions were successfully formed in the presence of the resulting PMPC- b-POEGMA, which acted as a stabilizer of water droplets in a chloroform continuous phase because the PMPC and POEGMA blocks were distributed to the water and chloroform phases, respectively. Next, the amphiphilic poly[poly(ethylene glycol) methacrylate] (PPEGMA) gel layer, which contained bis(2-methacryloyl)oxyethyl disulfide as a reductively responsive cross-linker, was prepared by inverse miniemulsion periphery RAFT polymerization from the PMPC- b-POEGMA that stabilized the W/O emulsions. The resulting PPEGMA gel capsules were colloidally stable in not only chloroform but also water without additional hydrophilic surface modification. The drug-release behavior from the PPEGMA gel capsules in response to dithiothreitol (DTT), which is a reducing agent, was investigated using fluorescein-conjugated dextran (FITC-Dex) as a model drug. The FITC-Dex release rate from the gel capsules in a phosphate buffer solution (pH 7.4, 20 mM) with DTT was fast compared to that without DTT. The reductively responsive FITC-Dex release is attributed to the cleavage of disulfide bonds that act as cross-links in the PPEGMA gel layer. The fascinating properties of the PPEGMA gel capsules suggest that they can provide a useful platform for designing drug carriers for protein and gene delivery and nanobioreactors.

(Invited) Reducing-Environment-Responsive Gel Capsules Prepared Via Inverse Miniemulsion Periphery RAFT Polymerization from Water-Soluble Emulsifier Stabilizing W/O Emulsions

Nano and micron-sized capsules having an inner water phase, such as liposomes and polymersomes, have been extensively studied as drug carriers because they can load water-soluble protein drugs. However, they have a few disadvantages of low mechanical strength and low loading efficiency of drugs. Therefore, the preparation of stable capsules having an inner water phase is required for constructing carriers for water-soluble protein drugs. In this study, the gel capsules consisting of an amphiphilic capsule membrane and an inner water phase were strategically prepared via inverse miniemulsion periphery reversible addition fragmentation chain transfer (RAFT) polymerization. This paper also describes the release of encapsulated model drugs from the gel capsules in response to a reducing environment. A water-soluble block copolymer emulsifier composed of PMPC block as a hydrophilic component and an amphiphilic poly[oligo(ethylene glycol) methacrylate] (POEGMA) block as a lipophilic component was synthesized via RAFT polymerization. The 1H NMR and gel permeation chromatography measurements revealed that the synthesized PMPC-b-POEGMA had 22 repeating units of PMPC and 171 repeating units of POEGMA with a narrow molecular weight distribution. The water-in-oil (W/O) emulsions were successfully formed by sonication of the water-chloroform mixture containing the resulting PMPC-b-POEGMA, which acted as a stabilizer of water droplets in a chloroform continuous phase because the PMPC and POEGMA blocks were distributed to the water and chloroform phases, respectively. The concentration of the PMPC-b-POEGMA emulsifier affected the droplet size and colloidal stability of the W/O emulsions, which was a similar attribute of conventional surfactants. The optimization of the PMPC-b-POEGMA concentration revealed that the 10 % (w/v) (relative to dispersed phase) of the PMPC-b-POEGMA emulsifier was suitable for the formation of W/O emulsions when chloroform and water were used as a continuous and a dispersed phase, respectively. Next, the amphiphilic poly[poly(ethylene glycol) methacrylate] (PPEGMA) gel layer, which contained bis(2-methacryloyl)oxyethyl disulfide (BMOD) as a reducing-environment-responsive crosslinker, was prepared by inverse miniemulsion periphery RAFT polymerization from the PMPC-b-POEGMA that stabilized the W/O emulsions. The resulting PPEGMA gel capsules were colloidally stable in not only chloroform but also water without additional hydrophilic surface modification because of the amphiphilicity of their gel capsule layer. The PPEGMA gel capsules were taken up by L929 cells with low cytotoxity. Furthermore, the drug-release behavior from the PPEGMA gel capsules in response to dithiothreitol (DTT), which is a reducing agent, was investigated using fluorescein-conjugated dextran (FITC-Dex) as a model drug. The FITC-Dex release rate from the gel capsules in a phosphate buffer (PB) solution (pH 7.4, 20 mM) with DTT was fast compared to that without DTT. When the BMOD-based crosslinks, which contain disulfide bonds, in the PPEGMA gel capsules layer are cleaved in a PB solution with DTT, a decrease in the crosslinking density of the layer induced an increase in the diffusion coefficient of FITC-Dex within the gel capsule layer. Therefore, the FITC-Dex release from the PPEGMA gel capsules was enhanced under a reducing environment. Although the application of PPEGMA gel capsules as smart drug carriers require further research regarding their structural change in response to reducing environments and controlling the drug release rate, the smart functions of the gel capsules can provide useful platforms for constructing a drug carrier that can deliver water-soluble drugs, such as low-molecular-weight drugs, proteins, and DNAs into the cytosol, which has a reducing environment. Figure 1

Biocompatible Stimuli-Responsive W/O/W Multiple Emulsions Prepared by One-Step Mixing with a Single Diblock Copolymer Emulsifier

Multiple water-in-oil-in-water (W/O/W) emulsions are promising materials in designing carriers of hydrophilic molecules or drug delivery systems, provided stability issues are solved and biocompatible chemicals can be used. In this work, we designed a biocompatible amphiphilic copolymer, poly(dimethylsiloxane)-b-poly(2-(dimethylamino)ethyl methacrylate) (PDMS-b-PDMAEMA), that can stabilize emulsions made with various biocompatible oils. The hydrophilic/hydrophobic properties of the copolymer can be adjusted using both pH and ionic strength stimuli. Consequently, the making of O/W (oil in water), W/O (water in oil), and W/O/W emulsions can be achieved by sweeping the pH and ionic strength. Of importance, W/O/W emulsions are formulated over a large pH and ionic strength domain in a one-step emulsification process via transitional phase inversion and are stable for several months. Cryo-TEM and interfacial tension studies show that the formation of these W/O/W emulsions is likely to be correlated to the interfacial film curvature and microemulsion morphology.

Poly(isobutylene) nanoparticles via cationic polymerization in nonaqueous emulsions.

The preparation of poly(isobutylene) (PIB) nanoparticles via cationic emulsion polymerization is presented. As a requirement, an oil-in-perfluoroalkane nonaqueous emulsion is developed, which is inert under the carbocationic polymerization conditions. To stabilize the dichloromethane/hexane droplets in the fluorinated, continuous phase, an amphiphilic block copolymer emulsifier is prepared containing PIB and 1H,1H-perfluoroalkylated poly(pentafluorostyrene) blocks. This system allows for the polymerization of isobutylene with number-average molecular weights (Mn) up to 27,000 g mol(-1). The particle morphologies are characterized via dynamic light scattering and electron microscopy. For Mn > 20,000 g mol(-1), the particles exhibit shape-persistence at room temperature and are ≈100 nm in diameter.

Preparation of a bis-demethoxy curcumin microemulsion based on pseudo-ternary phase diagrams and an orthogonal test analysis

A bis-demethoxy curcumin microemulsion was successfully prepared using the method of pseudo-ternary phase diagrams combined with an orthogonal test in a 3-phase system (O phase=active ingredient; S phase=surfactants; W phase=water). The best transparent region for preparing the bis-demethoxy curcumin microemulsion was formed when Termul-200 (an alkylphenol polyether block copolymer emulsifier) and sodium dodecyl benzene sulfonate (SDBS) (4 : 1 w/w) were used as surfactants (S phase), isopropanol (30% in S phase) as a co-surfactant, and a bis-demethoxy curcumin DMF solution (30%) as the active ingredient (O phase). According to the infinite dilution region of the best phase diagram, the best ratio among O, S and W phases for preparing the bis-demethoxy curcumin microemulsion was a weight ratio of 4.5 : 20 : 75.5. Stability tests showed that all the indicators of our prepared microemulsion met the storage stability criteria. Our results suggested that the combination of the pseudo-ternary phase diagram and orthogonal test analysis provided an effective approach for designing a microemulsion formulation.

Superparamagnetic Latex via Inverse Emulsion Polymerization

The structure-directing nature of block copolymers, combined with the “miniemulsion” polymerization process, facilitate synthesis of superparamagnetic latex loaded with nanometric magnetic iron oxide. A “double-hydrophilic” diblock copolymer (polyethylene oxide block-co-polymethacrylic acid), present during the precipitation of magnetic iron oxide, directs nucleation, controls growth, and sterically stabilizes the resulting 5 nm superparamagnetic iron oxide. After drying, the coated particles spontaneously repeptize into a mixture of hydroxyethylmethacrylate and methacrylic acid monomers, creating a ferrofluid-like dispersion. Inverse emulsification of the ferrofluid (magnetic particles plus monomer) into decane, aided by small amounts of diblock copolymer emulsifier along with ultrasonication, creates minidroplets (180 nm) filled with magnetic particles and monomer. Subsequent polymerization generates magnetic latex. Extensive characterization by scanning electron microscopy, transmission electron microscopy, dynamic light scattering, thermogravimetric analysis, magnetic measurements, and x-ray diffraction shows complete and uniform encapsulation of 5 nm magnetic iron oxide into latex of average diameter between 140 and 220 nm depending upon emulsifier concentration. The magnetically active latex contains 18 wt% magnetic iron oxide coated with hydrophilic polymers. In a minimum number of steps, the direct dispersion of magnetic particles in monomer and inverse miniemulsification process generates hydrophilic magnetic latex.

Synthesis and properties of titanium-nickel memory alloys made from elemental powders: S.Stover et al. (Forschungzentrum Jülich GmbH, Germany.)

Viscosity reduction by emulsification would greatly facilitate the exploitation and pipelining transportation of heavy oil, as well as oil sands/sludge washing. However, the final demulsification process to achieve separation of oil and water is tricky. Therefore, developing smart emulsifiers that can be switched on demand to achieve both effective emulsification and facile demulsification in subsequent oil/water separation process would be of great significance to the practical applications. In this paper, a zwitterionic copolymer emulsifier comprising acrylamide (AM), 2-(diethylamino)ethyl methacrylate (DEAEMA) and 3-[dimethyl-[2-(2-methylprop-2-enoyloxy)ethyl]azaniumyl]propane-1-sulfonate (SBMA) was prepared via reversible addition-fragmentation chain transfer (RAFT) polymerization for better control of the molecular weight, exhibiting good salt resistance and fast CO2-responsiveness. The prepared copolymer can efficiently emulsify heavy crude oil with a viscosity reduction rate up to 98.6% in highly mineralized water. While in the presence of CO2, the formed heavy oil/water emulsions can be rapidly broken to obtain oil-water two phases. Compared with traditional demulsification methods, the CO2-responsive strategy presented in this work can achieve a lower oil content in water (1.4%) after separation. Furthermore, the copolymer can also be applied to effectively emulsify and clean oily sludge. The CO2-responsive zwitterionic copolymer emulsifier demonstrated great potential in various engineering applications including exploitation and pipelining transportation of heavy oil, and oil sands/sludge washing, facilitating reduction of water pollution and energy saving.

From incompatible poly(aryl ether sulfone)/polyamide 4.6. blends to new impact resistant alloys by a synergistic combination of a block copolymer emulsifier and an impact modifier

AbstractThe compatibilization and impact modification of blends of a relatively new engineering plastic polyamide 4.6 (PA 4.6) and a poly(aryl ether sulfone) (PSU) are investigated. PSU‐b‐PA6 block copolymers, which can be easily synthesized by ring opening polymerization of ϵ‐caprolactam in the presence of a commercial PSU, were found to be very efficient emulsifiers for these incompatible blends. Small amounts (1–4%) of copolymer are sufficient to significantly reduce the particle size and to improve the tensile and impact properties. Combinations of the copolymer and an impact modifier (ethylene‐propylene rubber grafted with maleic anhydride) are synergistic and high impact PSU/PA 4.6 alloys are obtained in that way.

Use of an emulsifying block copolymer to improve time-dependent mechanical properties of polyethylene-polystyrene blends

The use of an emulsifying triblock copolymer to improve the room-temperature stress relaxation and creep behaviour of blends of the incompatible polymers high-density polyethylene (HDPE) and polystyrene (PS) has been evaluated. The volume content of PS in the blend was kept constant at 20%. Addition of a few per cent of the triblock copolymer emulsifier increased the internal stress level in the specimen as evaluated by stress relaxation experiments. This is due to improved adhesion between HDPE and PS. For blends without the triblock copolymer the creep rate can be rather high after prolonged loading times due to debonding at the interface between the polymers. Incorporation of the triblock copolymer emulsifier improves adhesion and thus reduces the creep rate. This increase in adhesion between HDPE and PS is also evident from scanning electron micrographs.