Emulsion Polymerization Technique Research Articles

Dual physically and chemically cross-linked polyelectrolyte nanohydrogels: Compositional and pH-dependent behavior studies

This study describes the composition-property relationship of a dual chemically and physically cross-linked nanohydrogel (NHG) containing a high concentration of hydrophilic pH-sensitive acrylic acid (AA). The physical and chemical cross-linking were incorporated using the aggregation of hydrophobic butyl acrylate (BA) and covalent bond of a bifunctional monomer (ethylene glycol dimethacrylate), respectively. Implementing a direct one-pot semi-batch emulsion polymerization technique in an acidic condition yielded monodispersed (PDI < 0.2) NHGs with a collapsed hydrodynamic radius of 60–100 nm. Titration studies revealed the significant effect of the chemical and physical cross-linking on the amounts of accessible carboxyl groups and their ionization behavior. These NHG dispersions displayed good colloidal stability over a wide pH and duration, the Donnan equilibrium is responsible for the observed swelling behavior of these NHGs.

Enhancing the dielectric properties of polymethyl methacrylate by using low loading graphene encapsulated styrene-butyl acrylate copolymer microspheres

With the rapid development of the electronics industry and electronic products, polymer nanocomposites with high dielectric constant and low dielectric loss will have great potential in various applications. In this work, a novel structure was obtained by absorbing reduced graphene oxide on the surfaces of styrene butyl-acrylate copolymer (rGO@SBA) microsphres through soap-free emulsion polymerization technique. Fourier-transform infrared spectrum characterization revealed the successful fabrication of rGO@SBA microspheres. SEM and TEM results indicated that rGO nanosheets were successfully loaded on the surface of SBA microspheres and the average diameter of rGO@SBA was increased to 650 nm. High dielectric permittivity rGO@SBA composites were obtained when the rGO loading was approximated to 2 wt%. The dielectric permittivity of rGO@SBA composites with 2 wt% rGO was 339 times higher than that of neat SBA. Furthermore, the electrical conductivity was also obviously enhanced. However, the dielectric loss of rGO@SBA composites was also inevitably increased. The rGO@SBA microspheres were further melt blended with polymethyl methacrylate (PMMA) matrix to obtain rGO@SBA/PMMA composites. The glass transition temperature of PMMA was increased with the content of rGO. The dielectric permittivity of rGO@SBA/PMMA composite with only 0.14 wt% rGO was increased to 15.5 at 1 kHz. On the other hand, the dielectric loss was controlled in a low level. SEM observation implied a segregated dispersion of rGO@SBA was realized in PMMA matrix. Our strategy provides a facile method to prepare high dielectric constant and low dielectric loss of rGO filled polymer composites through the fabrication of rGO encapsulated polymer microspheres.

Spectral and thermal studies on polyaniline–titanium dioxide nanocomposites by inverted emulsion techniques

Inverted emulsion polymerization technique using benzoyl peroxide, as an initiator, was used to prepare conducting polyaniline (PANI)/nano titanium dioxide (TiO2) composites. Polyaniline ratio was varied between 10 and 90% based on the yield percentage. The prepared nanocomposites were analyzed further by Fourier-transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, X-ray diffraction, and four probe conductivity. The FTIR spectrum of pure PANI and its composites with nano-TiO2 shows the vibrational bands due to benzenoid, quinoid ring stretching etc. Conductivity of pure polyaniline was observed to be 1.6 S cm−1 and upon the addition of nano-TiO2 the conductivity decreases. X-ray diffraction of PANI–nano TiO2 composites reveals that the crystalline nature of TiO2 is retained. TGA thermogram of nanocomposites monitored the thermal stability of pure PANI which improved by the addition of TiO2 in different ratios. SEM image reveal that nano-TiO2 particles are uniformly distributed in the PANI matrix.

Thermal Stability Evaluation of Polystyrene-Mg/Zn/Al LDH Nanocomposites.

A series of samples of Mg/Zn/Al LDHs (layered double hydroxides) materials was prepared by the co-precipitation and urea hydrolysis methods. They were modified with organic surfactants (acrylate and oleate anions) and characterized by X-ray diffraction, which corroborated the intercalation of anionic species into the interlayer space. The hydrophobized materials were incorporated at low contents (10 and 15 wt.%) to polystyrene, which was synthesized by emulsion polymerization techniques. The polymeric composites were analyzed by thermogravimetry to determine the decomposition temperature. The results demonstrated that the materials with Zn presented the greatest increment in the degradation temperature (7 °C < T < 54 °C). Moreover, the Friedman, Flynn–Wall–Ozawa, and Coats–Redfern models were compared to obtain the kinetic parameters of degradation process. The obtained order of decomposition of the Coats–Redfern model showed that the decomposition process occurs in at least two stages. Finally, the addition of environmentally friendly modified Layered Double Hydroxides (LDH) nanomaterials to the polystyrene (PS) matrix allowed for obtaining polymeric composites with higher thermal stability, retarding the decomposition process of PS.

Synthesis, characterization and toxicity assessment of a new polymeric nanoparticle, l-glutamic acid-g-p(HEMA)

The toxic effects of poly(HEMA)-based polymeric nanoparticles must be analyzed before their biomedical applications as drug delivery systems. The aim of the study was to characterize and evaluate the toxicity for its biocompatibility of a newly synthesized l-glutamic acid-g-p(HEMA) polymeric nanoparticle The nanoparticle was synthesized with surfactant-free emulsion polymerization and grafting techniques. Grafting efficiency was estimated at 58%. The nanoparticle shape was verified as nearly spherical by scanning electron microscopy. Atomic force microscopy images showed a rough surface topography. The nanoparticle had an average size of ~194.6 nm on zeta analysis, and the zeta potential value was −18 mV. Fourier transformed infrared spectroscopy revealed spectra from 750 to 4000 cm−1 and characteristic peaks of stretching bands. The swelling ratio was 46%. With 24-h exposure, p(HEMA) and l-glutamic acid-g-p(HEMA) did not have cytotoxic effects on a human bronchial epithelial cell line (16HBE) and human monocyte cell line by water-soluble tetrazolium salt 1 (WST-1) assay and lactate dehydrogenase assay (LDH). It did not show genotoxic potential by comet assay and did not have mutagenic effects on Salmonella typhimurium TA98, TA100, TA1535 and TA1537 strains by Ames test. The nanoparticle at 160 μg/ml showed 2% hemolytic activity on erythrocytes. On cell migration assay, the percentage closure difference between exposed and control cells was estimated at 21%. We found no irritation effect on Hen's egg test-chorioallantoic membrane test. We determined that the polymeric nanoparticle l-glutamic acid-g-p(HEMA) was biocompatible and has potential for use in a drug delivery system.

A novel and facile method to fabrication of broadband and semi-omnidirectional antireflective coatings with bowl-like pit structure

In the current work, excellent optical antireflective coatings with various surface morphologies are prepared combining with emulsion polymerization, sol-gel process and dip-coating technique. Among these antireflective coatings, bowl-like pit structure antireflective coatings show broadband and semi-omnidirectional antireflective properties. The mean transmittance of this kind of coatings reaches 99.5% and increases 7.2% compared with that of bare glass in the range of wavelength from 400 nm to 700 nm and the maximum transmittance is 99.8% when the incident angle is 0°. The mean transmittance of the coatings still keeps 97.7% and increases 6.7% compared with that of bare glass in the range of wavelength from 400 nm to 700 nm and the maximum transmittance is 98.5% when the incident angle is 30°. The coatings still show antireflective properties in a degree even the incident angle increases to 60°. The corresponding mechanism is also provided. More importantly, the whole process is simple, solvents free, low-cost and appropriate for large-scale production.

Mesoporous strontium ferrite/polythiophene composite: Influence of enwrappment on structural, thermal, and electromagnetic interference shielding

Strontium ferrite (SrFe12O19) and Strontium ferrite enwrapped polythiophene (SrF/PT) composites have been synthesized via sol-gel and in-situ emulsion polymerization techniques for the first time. The structural, morphological, magnetic, dielectric, and electromagnetic interference (EMI) shielding performances of these composites have been investigated. The composite possessing SrF:PT = 2:1 (SrF/PT-21) composition showed maximum shielding effectiveness (SE) of −31.64 dB at 15.73 GHz for 1 mm thick sample in the Ku-band (12.4–18 GHz) region, which is found to be higher than all composites and pristine SrFe12O19. This behavior is mainly attributed to the high dielectric and magnetic losses occurred within the material. The enwrapping of mesoporous SrFe12O19 nanoparticles by conducting PT further eased the electron transportation within the composite network that offered the greater impedance match for electromagnetic wave. Therefore, the composite may act as a promising microwave absorber with a lightweight, high thermal stability, and excellent SE ability for a broad frequency range.

Swelling kinetics and characterization of novel superabsorbent polymer composite based on mung bean starch-filled poly(acrylic acid)-graft-waste polystyrene

A novel superabsorbent polymer composite based on mung bean starch was prepared via emulsion polymerization technique of partially neutralized acrylic acid grafted onto waste polystyrene chain using ammonium persulfate and N,N′-methylenebisacrylamide as initiator and crosslinker, respectively. Fourier transform infrared confirmed the presence of mung bean starch in the grafting of polyacrylic acid and waste polystyrene. The introduction of starch in superabsorbent polymer greatly enhanced the swelling capacity with the optimum absorbency recorded at 59.3 g/g for 20% of starch loading. Meanwhile, thermogravimetric analysis showed enhance in thermal stability upon incorporation of mung bean starch.

Synthesis and properties of polyelectrolyte multilayered microcapsules reinforced smart coatings

The present research work focuses on the synthesis, characterization and properties of novel polyelectrolyte multilayered microcapsules used as smart additives in organic coatings for corrosion protection of steel parts. Urea formaldehyde microcapsules encapsulated with linalyl acetate (UFMCs), sensitive to mechanical stimulus, were synthesized by in situ emulsion polymerization technique. In the next step, dodecylamine, working as a pH stimulus corrosion inhibitor, was loaded into layers of polyelectrolyte molecules, polyethylenimine (PEI) and sulfonated polyether ether ketone (SPEEK). These were applied layer-by-layer over the microcapsules to form inhibitor containing multilayered urea formaldehyde microcapsules (MLUFMCs). In the next step, MLUFMCs (5.0 wt%) and UFMCs (5.0 wt%) were thoroughly dispersed into the epoxy resin and coated on cleaned steel. A comparison of the structural, thermal and anticorrosive properties indicates that coatings modified with multilayered capsules (PMLSCs) demonstrate good thermal stability, improved self-healing characteristics and higher corrosion resistance compared to the coating modified with urea formaldehyde microcapsules. The improved properties of PMLSCs can be attributed to efficient release of the encapsulated self-healing agent and corrosion inhibitor from the MLUFMCs. Therefore, epoxy coatings modified with the novel multilayered capsules may be attractive for corrosion protection of steel parts used in oil and gas and related industries.

Synthesis and Characterization of Nanosize Polyanthranillic Acid for Solid Polymer Electrolyte

Conducting polymer of anthranilic acid (PANA) has been synthesized through emulsion polymerization technique. Emulsion polymerization helps in slowing down kinetics of polymerization in comparison to one-phase polymerization and thereby induces formation of monodispersed. Reaction progress of conducting polymer formation is studied by UV–Vis and FTIR spectroscopy. Morphology of PANA is characterized by XRD, TEM, AFM and electrochemical techniques. XRD of conducting polymer depicts the less crystalline nature of polymer with crystallite size of 75 nm. Voltammetry has shown the electro-active nature of PANA. The performance of energy storage devices including pseudocapacitors is evaluated mostly by measuring energy density and power density.<div><br></div>

Dielectric investigations and charge transport in PS-PAni composites with ionic and nonionic surfactants

We present the preparation of polystyrene-polyaniline composites by an emulsion polymerization technique. Polyethylene glycol and dodecylbenzenesulfonic acid were used as nonionic and anionic surfactants, respectively, for emulsion preparation. Fourier transform IR spectroscopy, UV–vis spectroscopy, and thermogravimetric analysis were used to characterize the composites obtained. Surface morphological investigations by scanning electron microscopy showed that the emulsion technique using polyethylene glycol produces the most homogeneously distributed composites. Thermal analysis in conjugation with broadband dielectric spectroscopy revealed that as the composite conductivity increased, the temperature at which the maximum degradation rate was achieved gradually decreased. The dielectric investigation showed the α-relaxation process in pure polystyrene has an activation energy of 10.8 kJ/mol and is accompanied by a dielectrically determined glass transition temperature of about 366 K. After addition of polyaniline, this α-relaxation process was masked by the conductivity contribution. Moreover, polyaniline prepared with the anionic surfactant had higher electrical conductivity than that prepared with the nonionic surfactant because of its ordering effect on the structure. Surprisingly, the dependence of the conductivity of the composites on temperature, regardless of the preparation method, has two different trends, and each can be attributed to a different mechanism of charge transport.

Grafting of polyaniline by a dynamic inverse emulsion polymerization technique onto reverse osmosis membranes as an antibiofouling agent

This study reports on the benefits of an in situ interfacial dynamic inverse emulsion polymerization process under sonication of aniline in the presence of a commercial reverse osmosis (RO) membrane. This polymerization method is simple and much faster (5‐15 min) than systems reported in the literature. During polymerization, the membranes are coated with polyaniline (PANI) as verified by high‐resolution scanning electron microscopy (HRSEM) images and Fourier‐transform‐infrared (FTIR) measurements. A colony‐counting antimicrobial activity test showed that whereas the reference RO membrane developed a large bacterial colony, the polyaniline‐coated RO membrane had no colonies at all. Surface resistivity was the lowest when the pH levels were below 6, which corresponded to the polyaniline‐grafted conductive layer. The membrane flow properties were only modified slightly as a result of the polyaniline grafting, compared with a pristine reference membrane.

Particle Size Reduction of Polyaniline Assisted by Anionic Emulsifier of Sodium Dodecyl Sulphate (SDS) Through Emulsion Polymerization

Reduction of particle size of Polyaniline (PANI) evaluated after anionic surfactant assisted polymerization reaction was observed during synthesis. The use of Sodium Dodecyl Sulfate (SDS) during the reaction has reduced the particle size of PANI to the smallest 212 nm from original size 713 nm obtained from a synthesis of SDS free. The single compound of SDS has specific fingerprint at wavenumbers of 1247 and 1216 cm-1 indicating an asymmetric stretching, vibration and a symmetric stretching vibration of SO2 molecule at 1080 cm-1. After SDS assisted polymerization reaction completely, the fingerprint specifically appears in the range of 950 - 1000 cm-1 wavenumber for SO2 molecule peaks. It indicates that there was SO2 molecule bonded into PANI molecule. It was obtained that the higher SO2 content in PANI of a high SDS concentration shows a wider of spectra and higher absorbency. In addition, there was no pH effect during the polymerization reaction under various SDS concentrations. It is concluded that the particles of PANI were reduced with the addition of SDS during polymerization reaction. The smallest average particle size obtained through the emulsion polymerization technique containing 0.67 % SDS was 212 nm.

Inverse emulsion polymerization of triple monomers of acrylamide, maleic anhydride, and styrene to achieve highly hydrophilic–hydrophobic modified polyacrylamide

ABSTRACTThe purpose of this study was the production of copolymers and terpolymers with highly hydrophilic–hydrophobic properties, using inexpensive and available monomers as potential enhancing oil recovery (EOR) and water production control agents for high‐temperature and high‐salinity (HTHS) oil reservoirs. For this purpose, several copolymers and terpolymers with different molar percentage of acrylamide/styrene, acrylamide/maleic anhydride, and acrylamide/styrene/maleic anhydride were synthesized by the inverse emulsion polymerization technique. The presence of hydrophobic styrene and hydrophilic maleic anhydride monomers in the copolymer and terpolymer structure, provided some unique properties compared to polyacrylamide, was confirmed by several analyses including HNMR, elemental analysis, FTIR, SEM, TGA, and DSC. Simulating HTHS oil reservoir condition under high salinity, temperature, and shear rate, the rheological studies suggested unlike traditional EOR agents such as polyacrylamide, the viscosity of the copolymer, and terpolymer aqueous solutions showed a considerable increase after a critical polymer concentration and less reduction with the salt increment at both ambient and elevated temperatures. Furthermore, the swelling ratio of the insoluble terpolymers measured versus the time and temperature in salt water increased with the maleic anhydride mole fraction, decreased with the salt concentration, and showed a maximum value at around 57 °C. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47753.

N‐doped C‐dot embedded fluorescent and thermo‐responsive p(NIPAAm) microgel composites

In this study, the synthesis of N‐doped C‐dot embedding poly(N‐isopropylacrylamide) (p(NIPAAm)) particle composites via surfactant‐free emulsion polymerization technique was reported. The fluorescent property of N‐doped C‐dot combined with thermo‐responsive properties of p(NIPAAm) particles (p(NIPAAm)/C‐dot) render smart materials with intriguing properties. The particle size and volume phase transition temperature (VPTT) values of p(NIPAAm) based particles was altered in accord with the amount of embedded N‐doped C‐dot within p(NIPAAm) particles between 1,000–750 nm and 35.4–37.2°C, respectively. On the other hand, N‐doped C‐dot within p(NIPAAm) particles was afforded fluorescent properties with emission peak at around 460 nm. The effect of the amount of N‐doped C‐dot within p(NIPAAm) particles, temperature and pH were investigated on the fluorescent properties of N‐doped C‐dot embedded p(NIPAAm) particle composite. POLYM. COMPOS., 40:3895–3903, 2019. © 2019 Society of Plastics Engineers

Enhancing the electrochemical performance of lithium ion battery anodes by poly(acrylonitrile–butyl acrylate)/graphene nanoplatelet composite binder

Graphene nanoplatelet (GnP), which consists of small stacks of graphene, is used as a reinforcement to enhance the performance of the poly(acrylonitrile-butyl acrylate) (PANBA) binder in a lithium ion battery (LIB). To the best of our knowledge, this is the first time that a conductive nanofiller such as GnP has been used in a conventional water-dispersed polymer and applied as a binder for LIB. Our so-called PANBA/GnP nanocomposites are made with either 0.5 wt%, 1 wt%, or 2 wt% of GnP. The nanocomposites are synthesized via an in situ emulsion polymerization technique and are very well-dispersed, homogeneous, and stable for at least 6 months. The elongation and electrical conductivity of the PANBA/GnP nanocomposites exceed those of the PANBA non-filled polymer, and the PANBA/GnP nanocomposite binder ultimately enhances the electrochemical performance of the high-capacity silicon/graphite mixture anode.

Electrical conductivity of polyaniline (PANI) assisted by anionic surfactant through emulsion polymerization technique

In this work, Polyaniline (PANI) was synthesized through emulsion polymerization assisted by sodium dodecyl sulfate (SDS) surfactant to investigate effects of surfactant to the electrical conductivity. The amount of SDS used has mol to the total quantity ratio of respectively 0.25%, 0.67%, 1.00%, and 2%. The emulsion aniline polymer obtained from the reaction was confirmed by FTIR. The addition of SDS surfactant as an additional component in the reaction solution, led to the chemical reaction run with a relatively slow rate. It indicated by a relatively long reaction time for an increase in the temperature of reaction solution. The viscosity of the emulsion aniline polymer increased with the addition of SDS. The higher amount of SDS is added, the higher the initial viscosity value of the emulsion. Electrical conductivity value evaluated by Four Point Probe (FPP) showed that the emulsion polymers of aniline doped with 80 ml Perchloric Acid (HQO4) have an ohmic relationship between current and voltage from which the conductivity was derived. It was found that the electrical conductivity value of doped PANI assisted by surfactant reached two times higher than that of surfactant-free synthesized PANI. The highest electrical conductivity value obtained is 3.97 S/cm.

Evaluation of Thermal and Mechanical properties of Styrene- Butadiene Rubber-nanocomposite by using Tin oxide as filler

The Copolymer SBR- nano tin oxide composite was synthesized by emulsion polymerization technique. The nanocomposite SBR- nano tin oxide composition was characterized by elemental analysis and FTIR spectroscopy. Non-isothermal thermogravimetric investigations have been completed to decide their method of deterioration and comparative thermal strength. The thermal decay conduct of composites was examined by utilizing thermogravimetric techniques in air climate at a warming rate of 10°C min-1. FC and SW strategies were utilized to ascertain the active parameters, for example, thermal activation energy (Ea) and the order of reaction (n). The energy of activation decided with the assistance of this technique was in great concurrence with one another.

Design optimization and fabrication of a wideband microwave absorber based on dual-phase dielectric semi-metallic nanocomposite

Dual-phase nanocomposites consisting of dielectric polyaniline (PA) of diameter ∼50 nm and semi-metallic expanded graphite (EG) were synthesized by in situ emulsion polymerization technique. This involved integrating EG in varied proportions of EG (0.00, 0.15, and 0.25 wt %) into PA and mixing with novolac phenolic resin (NPR) (10, 20, and 30 wt %) to tailor the microwave absorption properties ofrelative complex permittivity εr(ω) = εr′ – jεr″, where εr′ and εr″ are real and imaginary parts of complex permittivity in the X-band frequency. The measured frequency-dependent εr(ω) values showed significantly enhanced values for PA/EG–NPR nanocomposites with εr′ ∼ 14.5 εr″ ∼ 25.6, and (εr″/εr′) > 1.5 compared with PA–NPR nanocomposites with (εr″/εr′) > 0.25 and were analyzed using the principle of capacitance variation with filler concentration. Based on the Transmission Line Model, design optimization of single-layer microwave absorbers was performed for the developed nanocomposites. The fabricated absorber exhibited measured reflection loss RLm ∼32 dB at 9.7 GHz and RLm −17 dB at 10.9 GHz for 30 wt % PA/EGNPR (EG = 0.15) composite of thickness 3 mm and 20 wt % PA/EG–NPR (EG = 0.25) of thickness 2.5 mm, respectively, with −10 dB absorption bandwidth of 2.4 and 1.7 GHz in the X-band. A triangular-lattice perforated design for PA/EG composite was proposed to enhance the broad impedance matching and absorption bandwidth in the X-band.

Investigation of thermal energy storage properties of a microencapsulated phase change material using response surface experimental design methodology

The response surface experimental design methodology was used to investigate thermal energy storage properties of the microencapsulated phase change material (MicroPCM). The capric acid and oleic acid mixture in the presence of hexadecane were encapsulated with styrene-divinylbenzene copolymer shell by emulsion polymerization technique. Response surface design experiments were conducted to determine the effect of three factors, namely, the shell:core ratio, emulsification time and crosslinker percentage at three distinctly different levels. Main effects and interaction effects of the factors on the latent heat of melting (ΔHm), the amount of produced MicroPCM and the encapsulation ratio were examined using statistical methods. The regression models were derived fully fit the experimental data. According to the statistical analysis results, the most significant effect on the thermal energy storage capacity, the amount of MicroPCM and the encapsulation ratio was attributed to the shell:core ratio. The properties of optimal MicroPCM were investigated by Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared Spectroscopy (FT-IR). The analysis results demonstrated that optimal MicroPCM with its latent heat of fusion value (123 J/g) and encapsulation ratio (85.85%) can be accepted as a good candidate for thermal energy storage applications.