Emulsion Polymerization Of Styrene Research Articles

Bioderived Thiol-Ene Emulsion Polymerization for Hybrid Latex Particles.

The thiol-ene emulsion polymerization of three dienes synthesized from bioderived compounds, and subsequent preparation of core-shell polymer latexes, is reported. Levoglucosan (LGA), levogucosenone (LGO) and isosorbide were first modified with 4-pentenoic acid to install polymerizable groups. These monomers were used along with a dithiol to prepare poly(thioether) particles via ab initio emulsion polymerization using potassium persulfate as initiator and sodium dodecyl sulfate as surfactant. The structure of the diene significantly influenced the size of the resulting polymer latex particles. Given their low glass transition temperature, the LGA-derived poly(thioether) particles were used as a seed for the seeded emulsion polymerization of either styrene or methyl methacrylate. Core-shell latex particles with a high Tg core and a low Tg bioderived shell were formed, as verified by electron microscopy and in agreement with theoretical predictions of the equilibrium particle morphology based on the interfacial tensions of each particle phase.

Synthesis of ZnO/Poly(Styrene‐co‐Methacrylic Acid) Hybrid Polymer Particles for Enhanced UV‐Visible Photodegradation of Methylene Blue

AbstractIn this study, a series of submicron‐sized functional polymer particles poly(Sty‐co‐MAA) with variable methacrylic acid (MAA) content were prepared by soap‐free emulsion polymerization of styrene (Sty), methacrylic acid (MAA), and ethylene glycol dimethacrylate (EGDMA). The number‐average diameters of polymer particles (Dn) were in the range of 0.11 to 0.19 μm. A decrease in particle size was observed with increasing the molar ratio of MAA comonomer in the recipe. ZnO/poly(Sty‐co‐MAA) hybrid polymer particles were prepared by seeded emulsion copolymerization in presence of zinc oxide nanoparticles (ZnO NPs) as seed particles synthesized using Citrus lemon aqueous leaf extract. Scanning electron microscopy (SEM), transmission electron microsphere (TEM), X‐Ray Diffraction (XRD), and Fourier transformed infra‐red (FT‐IR) analysis were performed to characterize polymer particles. The crystalline size of ZnO NPs and ZnO/poly(Sty‐co‐MAA) hybrid polymer particles calculated from XRD analysis were 20.75 and 29.85 nm, respectively. These hybrid polymer particles were applied as photocatalyst in the photodegradation of methylene blue (MB) dye under UV irradiation, which showed high catalytic activity with degradation efficiency of 85.70 % at room temperature compared to bare ZnO NPs.

Environmentally Friendly Synthesis of Polymer Nanoparticles in a Packed Reactor Using Glass Beads

AbstractPolymeric particles less than 100 nm in size (polymer nanoparticles), which are useful in the fields of medicine and so on, are synthesized through emulsion polymerization, wherein surfactants are essential for maintaining their dispersion stability, contaminating particle surfaces and causing high environmental pollution. The soap‐free emulsion polymerization (SFEP) of styrene in a packed reactor using microglass beads enables the synthesis of polymer nanoparticles without surfactants. Ultraviolet irradiation is used for radical polymerization using an initiator during the SFEP of styrene. The reaction space in the packed reactor is controlled by the size of glass beads to be filled in the reactor. A decrease in the size of the glass beads narrows the reaction space, causing the average polystyrene particle size to reach 27.3 nm and suppress convection flow by the wall of the glass beads, thereby limiting particle motion and preventing particle growth through particle collisions.This article is protected by copyright. All rights reserved

Synthesis of dimpled polymer-silica nanocomposite particles by interfacial swelling-based seeded polymerization.

Dimpled polymer-silica nanocomposite particles have the combined advantages of dimpled particles and polymer-silica nanocomposite particles. This study presents a novel approach to prepare these particles by interfacial swelling-based seeded polymerization. Polystyrene-silica (PS-SiO2) nanocomposite particles are first prepared by emulsion polymerization of styrene in the presence of glycerol-functionalized silica sols and then dimpled polymer-SiO2 particles are fabricated by interfacial swelling of butyl acrylate (BA)/toluene and subsequent seeded polymerization of BA with the PS-SiO2 particles as seeds. The effects of different parameters, such as the amount of surfactant used in the PS-SiO2/H2O dispersion, BA/toluene mass ratio, PS-SiO2/H2O mass ratio and stirring rate, on the formation of the dimpled particles are investigated. Optimization of the seeded polymerization conditions allows a relatively high percentage of dimpled particles to be achieved.

Evidence of gel effect and living free radicals in particles: Soap‐free emulsion polymerization of styrene by using 2,2'‐azobis(isobutyronitrile)

AbstractBatch, in situ seeded and stepwise dosing monomer, and normal seeded soap‐free emulsion polymerizations (SFEP) of styrene were carried out by using the oil‐soluble 2,2′‐azobis(isobutyronitrile) as initiator. Gel permeation chromatography (GPC) and scanning electron microscopy were employed to characterize the experimental results. Typical auto‐accelerative effect in the bulk free‐radical polymerization was also observed in the macro‐kinetics of batch SFEP at 60 and 65°C. Flat‐roof GPC curves appeared at the post‐auto‐acceleration. In addition, in particles exhibited a positive relationship with the size of particles. The bigger size the larger . In the in situ seeded polymerization, the flat‐roof GPC curves of seed turned into the asymmetric Gaussian type exhibiting the great increase of the fraction of larger with the sequential addition of styrene. In addition, the number of seeds was kept constant throughout the polymerization. It indicated that the free radicals were generated and confined in the growing particles. In the normal seeded polymerization, showed a strong dependence on the average assigned amount of St per seed particle. The more monomers per seed particle the larger was gained. Based on these results, it was postulated that the free radicals were living due to the gel effect occurring in particles, namely that the free radicals were segregated by the dry polymer chains. The kinetics model was also given based on the microdroplets theory.

Double hydrophilic thermo-sensitive macro-RAFT agents as stabilizers and control agents in styrene emulsion polymerization

Double hydrophilic thermo-sensitive macro-RAFT agents as stabilizers and control agents in styrene emulsion polymerization

In-situ formation of nitrogen doped microporous carbon nanospheres derived from polystyrene as lubricant additives for anti-wear and friction reduction

This study presents a nitrogen-doped microporous carbon nanospheres (N@MCNs) prepared by a facile polymerization–carbonization process using low-cost styrene. The N element in situ introduces polystyrene (PS) nanospheres via emulsion polymerization of styrene with cyanuric chloride as crosslinking agent, and then carbonization obtains N@MCNs. The as-prepared carbon nanospheres possess the complete spherical structure and adjustable nitrogen amount by controlling the relative proportion of tetrachloromethane and cyanuric chloride. The friction performance of N@MCNs as lubricating oil additives was surveyed utilizing the friction experiment of ball-disc structure. The results showed that N@MCNs exhibit superb reduction performance of friction and wear. When the addition of N@MCNs was 0.06 wt%, the friction coefficient of PAO-10 decreased from 0.188 to 0.105, and the wear volume reduced by 94.4%. The width and depth of wear marks of N@MCNs decreased by 49.2% and 94.5%, respectively. The carrying capacity of load was rocketed from 100 to 400 N concurrently. Through the analysis of the lubrication mechanism, the result manifested that the prepared N@MCNs enter clearance of the friction pair, transform the sliding friction into the mixed friction of sliding and rolling, and repair the contact surface through the repair effect. Furthermore, the tribochemical reaction between nanoparticles and friction pairs forms a protective film containing nitride and metal oxides, which can avert direct contact with the matrix and improve the tribological properties. This experiment showed that nitrogen-doped polystyrene-based carbon nanospheres prepared by in-situ doping are the promising materials for wear resistance and reducing friction. This preparing method can be ulteriorly expanded to multi-element co-permeable materials. Nitrogen and boron co-doped carbon nanospheres (B,N@MCNs) were prepared by mixed carbonization of N-enriched PS and boric acid, and exhibited high load carrying capacity and good tribological properties.

Thermal and Dielectric Investigations of Polystyrene Nanoparticles as a Viable Platform-Toward the Next Generation of Fillers for Nanocomposites.

Nanoparticles are often used as fillers for enhancing various properties of polymer composites such as mechanical, electrical, or dielectric. Among them, polymer nanoparticles are considered ideal contenders because of their compatibility with a polymer matrix. For this reason, it is important that they are synthesized in a surfactant-free form, to obtain predictable surface and structural properties. Here, we synthesized a series of polystyrene nanoparticles (PS NPs), by emulsion polymerization of styrene, using varying amounts of divinylbenzene as a crosslinking agent and sodium 4-vinylbenzenesulfonate as a copolymerizing monomer surfactant-"surfmer". Using "surfmers" we obtained surfactant-free nanoparticles that are monodisperse, with a high degree of thermal stability, as observed by scanning electron microscopy and thermogravimetric investigations. The prepared series of NPs were investigated by means of broadband dielectric spectroscopy and we demonstrate that by fine-tuning their chemical composition, fine changes in their dielectric and thermal properties are obtained. Further, we demonstrate that the physical transformations in the nanoparticles, such as the glass transition, can be predicted by performing the first derivative of dielectric permittivity for all investigated samples. The glass transition temperature of PS NPs appears to be inversely correlated with the dielectric permittivity and the average diameter of NPs.

Methacrylic acid‐based amphiphilic block‐random copolymer stabilizers for emulsion polymerization

AbstractThe emulsion polymerization of styrene was investigated using polystyrene‐b‐[polystyrene‐r‐poly(methacrylic acid)] amphiphilic block‐random copolymers (BRCs) of different compositions as stabilizers. These stabilizers with molar masses <20,000 g/mol, which possess unique dispersion behaviour (i.e., self‐assembly with low aggregation numbers) when dissolved in aqueous medium at alkaline pH, were prepared by the nitroxide‐mediated bulk polymerization of styrene to achieve a desired molar mass followed by chain extension by batchwise addition of styrene and methacrylic acid monomers to obtain the stabilizing group. Emulsion polymerizations of styrene stabilized by these BRCs yielded stable latexes with particle diameters that range between 30 and 150 nm. When different concentrations of the stabilizer (2–3.5 mM) were utilized for emulsion polymerization of styrene, a similar novel emulsion polymerization mechanism observed previously by our group for the acrylic‐acid based amphiphilic BRCs was also seen, further validating the difference between this class of polymeric surfactants and conventional small molecule surfactants, block copolymers, or alkali soluble resins. The performance of methacrylic‐acid based BRCs was more efficient and yielded higher surface coverage of the polystyrene latexes when compared to the acrylic‐acid based BRCs as a result of the more hydrophobic nature of the former.

Morphology of polypropylene/polystyrene composite particles prepared by seeded emulsion polymerization: influence of azo initiator intrinsic charge

The morphologies of polypropylene (PP)/polystyrene (PS) composite particles obtained using different type of the initiator in the seeded emulsion polymerization of styrene with multi-hollow PP seed particles.

Cost-Effective Control of Molecular Weight in Ultrasound-Assisted Emulsion Polymerization of Styrene.

This paper focuses on the determination of economically most feasible conditions to obtain polystyrene with various target molecular weights through ultrasound-assisted emulsion polymerization. Briefly, batch polymerizations of styrene have been performed by ultrasound-assisted emulsion polymerization process using different reaction feed compositions. Polymerization rates were calculated using the monomer conversions at various reaction times. Also, molecular weights of the synthesized polymers, as well as the Mark-Houwink constants, were determined by intrinsic viscosity and gel permeation chromatography measurements. It was found that the polydispersity index of the polymers is ranging from 1.2 to 1.5, and the viscosity average molecular weights are in between 100000-1500000 g/mol depending on the reaction conditions. Finally, model equations were also developed for response variables, and the most economical ways of reaching various target molecular weights were interpreted by response surface methodology based multi objective optimization.

Dispersion Mechanism of Styrene–Butadiene Rubber Powder Modified by Itaconic Acid and Its Toughening Effect on Oil Well Cement

Styrene-butadiene rubber (SBR) has been extensively applied to enhance the toughness of hardened cement. The instability of existing liquid latex leads to difficulties in storage and transportation, and even performance regression. Thus, the well-dispersed carboxylated butylbenzene (SISBR) latex powders were fabricated through the seed emulsion polymerization of liquid polybutadiene (LPB), styrene (St), itaconic acid (IA), and sodium p-styrenesulfonate (SSS) to overcome the difficulties. The dispersion performance of latex powders with various IA amounts was quantitatively evaluated using particle size distribution, zeta potential, and ultraviolet-visible spectrophotometry. Results showed that the carboxylic ionic (COO-) from IA enhanced the dispersing abilities of SISBR latex powders, which ensured the uniform distribution in water. Based on this, the influence of latex powder on cement was assessed mainly by fluidity, isothermal heat flow calorimetry, X-ray diffraction (XRD), and triaxial mechanical testing. Results showed the fluidity and dispersion performance of cement were improved with more IA in latex, while the hydration of cement was retarded due to excessive adsorption of carboxyl (-COOH) groups in IA. Triaxial mechanical testing showed that cement with SISBR-3 (latex containing 3% IA) exhibited the minimal elastic modulus of 3.16 GPa, which was lower than that of plain cement (8.34 GPa).

Modeling Polystyrene Homogeneous‐Coagulative Nucleation in Pickering Emulsion Polymerization

AbstractInvestigation of particle nucleation in surfactant‐free emulsion polymerization of styrene using Laponite clay as Pickering stabilizer is considered. The effective number of clay platelets contributing to the surface charge of the polymer particles is calculated, and used to estimate their stabilizing efficiency. A coagulative nucleation mechanism is proposed and the coagulation coefficient is calculated using the Derjaguin–Landau–Verwey–Overbeek theory. The Hamaker constant involved in the attractive potential of the clay‐polymer composite particles is measured experimentally. The model is found to fit the experimental data in terms of the number of nucleated particles and the nucleation period. The effective number of clay platelets contributing to the surface charge is found higher than the number of platelets allowing full polymer latex surface coverage at the end of nucleation. Moreover, efficient stabilization against coagulation requires almost complete coverage.

An emulsion swelling route to surface-wrinkled polystyrene-silica colloidal nanocomposite particles

There is increasing interest in the fabrication of surface-wrinkled colloidal particles. This paper reports a facile emulsion swelling route to prepare surface-wrinkled polymer-silica core-shell nanocomposite particles. Submicrometer-sized polystyrene-silica (PS–SiO 2 ) nanocomposite particles were first prepared by emulsion polymerization of styrene using glycerol-functionalized ultrafine aqueous silica sols, and then surface-wrinkled PS−SiO 2 particles were obtained by swelling the PS−SiO 2 particles with a toluene/water emulsion and subsequent drying. The key to success is simply the use of the PS-SiO 2 core-shell nanocomposite particles prepared by emulsion polymerization, in which the SiO 2 shell was composed of individual and discrete ultrafine SiO 2 sols. The influence of various swelling parameters including toluene/particle ratio, surfactant concentration, swelling temperature and swelling time on the formation of the wrinkled nanocomposite particles was studied. Furthermore, hollow wrinkled silica thin shells composed of silica nanoparticles could be obtained by calcination of the wrinkled nanocomposite particles. This method represents a new paradigm in the preparation of surface-wrinkled polymer colloids. This paper reports a facile route to prepare surface-wrinkled polymer-silica nanocomposite particles with a thin silica shell through the judicious combination of emulsion polymerization and emulsion swelling. • A facile emulsion swelling route to prepare surface-wrinkled polymer-silica core-shell nanocomposite particles is reported. • The protocol involves judicious combination of emulsion polymerization and emulsion swelling. • Hollow wrinkled silica thin shells composed of silica nanoparticles could be obtained by calcination. • This method represents a new paradigm in the preparation of surface-wrinkled polymer colloids.

Polystyrene nanospheres coated red phosphorus flame retardant for polyamide 66

AbstractAs a halogen‐free flame retardant, red phosphorus (RP) is unstable in air due to its slow oxidation. The shortcomings of RP include strong water absorbing proneness, high friction sensibility and poor thermal stability. The characteristics of polystyrene (PS) are thermostability and fluidity in melt, which can improve the compatibility of RP and the organic matrixes. Using PS as a coating material can improve the characteristics of strong water absorbing proneness of RP. Herein, the polystyrene nanospheres coated RP (PSNS@RP) flame retardant was successfully prepared via emulsion polymerization of styrene. The result shows that the release of phosphine from the PSNS@RP is greatly reduced. The ignition point is increased by about 200°C, and the moisture absorption rate can be reduced by 40 times. The effect of PSNS@RP on the flame retardancy and thermal stability of polyamide 66 (PA66) were studied in detail. Compared with PA66, the limiting oxygen index (LOI) of the PSNS@RP/PA66 composite is increased from 24.8% to 34.2%. The flame retardant grade is enhanced to be UL94 V‐0. The peak heat release rate (PHRR) is decreased from 1444.5 to 420.9 kW m−2, the total heat release (THR) is decreased from 145.8 to 94.2 MJ m−2, and the total smoke production (TSP) is also reduced by 35%. Therefore, the as‐synthesized PSNS@RP has excellent flame retardant and smoke‐suppressing properties for PA66.

E7 nematic liquid crystal encapsulated in a polymeric photonic crystal

This study presents the synthesis and characterization of nano encapsulated liquid crystals in the polymer (nano-ELCP) obtained by the soap-free emulsion polymerization of the system styrene (ST) and acrylic acid (AA) in the presence of the liquid crystal E7 (LC). The obtained emulsion and the photonic crystal film (PC) were characterized by optical microscopy, SEM, DLS, UV–Vis, DSC, TEM, GPC, TGA, and fluorescence spectroscopy to highlight the encapsulation of E7 in the polymer particles and their properties. The DLS and SEM analyses confirmed a narrow polymer particle size distribution and the possibility to form highly arranged PCs, which contain the dispersed LC. The DSC, TEM, and TGA analyses sustain the encapsulation of E7 with an LC content of 11.87 % and 25.19 % (weight %) for ST-AA-E7-1 and ST-AA-E7-2, respectively. An increase in the fluorescence response was demonstrated for the polymer encapsulated LC which can be attributed to PCs that augments the intensity of the nematic crystal fluorescence response, in the absence of external stimuli.

Construction of insulating layers on conductive nickel-plated core particles by thermal fusion of heterocoagulated polymer shell particles

In this study, we developed a method for fabricating conductive particles with an insulating layer on the surface, which can be applied to anisotropic conductive films. Core-shell particles were prepared from conductive nickel-plated core particles and positively charged polystyrene (PSt) shell particles carrying phosphonium groups on their surface by the heterocoagulation technique. The effect of alkyl chain lengths (ethyl, n-butyl, and n-octyl) of (4-vinylbenzyl)trialkylphosphonium chloride on the interfacial properties was investigated by surface tension measurement. Monodisperse PSt shell particles with a controlled particle size were successfully synthesized by emulsifier-free emulsion polymerization of styrene, (4-vinylbenzyl)triethylphosphonium chloride, and n-butyl acrylate. The effects of stirring time, temperature, NaCl concentration, and PSt shell particle concentration on heterocoagulation between the nickel-plated core particles and PSt shell particles were investigated. Uniform core-shell particles with a coverage of 60% could be prepared even though the heterocoagulation temperature was below the glass transition temperature and the NaCl concentration was below the critical coagulation concentration of the PSt shell particles. When the core-shell particles obtained through the heterocoagulation process were heated above the glass transition temperature of the shell particles for 6 h, a smooth polymeric insulating layer with melted shell particles was successfully formed on the surface of the nickel-plated core particles.

CuO Nanoparticle@Polystyrene Hierarchical Porous Foam for the Effective Encapsulation of Octadecanol as a Phase Changing Thermal Energy Storage Material

CuO nanoparticle-doped hierarchical porous polymeric frameworks can be used for shape stability of octadecanol (OD) as a phase change material (PCM) for latent heat energy storage (LHTES) applications. A hierarchical porous foam polymer was synthesized by high internal phase emulsion polymerization of styrene and divinylbenzene doped with/without CuO. The synthesized high internal phase templated polymers (PHPs) with hierarchical pores were capable of absorbing up to 75 wt % OD without seepage behavior. The morphological, structural, and thermal behavior of PHPs/OD and PHPs@CuO/OD composite PCMs was determined using scanning electron microscopy (SEM)/energy-dispersive X-ray analysis (EDX), Brunauer–Emmett–Teller (BET) surface area analyses, Fourier transform infrared spectrophotometry (FT-IR), differential scanning calorimetry (DSC) analysis, and thermogravimetric analysis. Thermal analysis results revealed that PHP containing 75 wt % OD has an LHTES capacity of 190.4–194.0 J/g in the temperature range of 52.0–53.0 °C. The chemical and thermal stabilities of the developed composite PCMs were tested with repetitive thermal cycles. After 0.25 wt % CuO nanoparticle doping, the thermal conductivity of the composite PCM increased up to 86 and 17% compared to PHP and pure OD, respectively. Heat storage/releasing times of PHP@CuO/OD reduced about 20–22% relative to those of PHP/OD because of improved thermal conductivity. The thermal stability of PHP/OD and PHP@CuO/OD composites increased from 196 to 278 °C and 251 °C, respectively, compared to pure OD. The results exposed that especially PHP@CuO/OD composite PCMs are good candidates for LHTES applications because of their considerably high LHTES capacity.

Photonic crystal films with upconversion luminescence based on the self-assembly of polystyrene encapsulated NaYF4:Ln3+ composite microspheres for dual-mode optical code

The design and fabrication of advanced materials with multiple optical states for constructing security code are of great value in anti-counterfeiting. Herein, novel upconversion photonic crystal (UCPC) films with tunable luminescence and structural color were prepared by vertical deposition of polystyrene encapsulated NaYF4:Ln3+ (CSNPs@SiO2/PS) composite microspheres. The composite microspheres were synthesized by sequential coating technology. Firstly, NaYF4:Ln3+@NaYF4 core/shell nanoparticles (CSNPs) were synthesized and served as upconversion luminescent emission centers. Then, the CSNPs were further coated by a SiO2 shell with pendant double bond to form CSNPs@SiO2-MPS. Afterward, mono-dispersed CSNPs@SiO2/PS composite microspheres were synthesized by emulsion polymerization of styrene in the presence of CSNPs@SiO2-MPS. By tailoring the doped lanthanide ions in CSNPs and adjusting the diameter of the composite microspheres, UCPC films with diverse upconversion fluorescence and structural color can be obtained. As a proof of concept, these different kinds of UCPC films were employed as information coding units to construct dual-mode anti-counterfeiting code. Our protocol provided a new security strategy for information storage.

Preparation and properties of antibacterial styrene‐acrylic emulsion based on bis‐quaternary ammonium salt‐containing mono‐methacrylates as polymerizable antibacterial agents

AbstractWith the aim to prepare antibacterial styrene‐acrylic emulsion, a series of bis‐quaternary ammonium salt‐containing mono‐methacrylates MEQABr‐x(x = 12, 14, 16) were synthesized as polymerizable antibacterial agents via two steps. The chemical structures of MEQABr‐x(x = 12, 14, 16) were confirmed by proton nuclear magnetic resonance (1H‐NMR) and Fourier transform infrared (FTIR). The Minimum inhibitory concentration (MIC), Minimum bactericidal concentration (MBC), and Critical micelle moncentration (CMC) results showed that MEQABr‐x(x = 12, 14, 16) had antibacterial properties and surface properties which was influenced by its alkyl chain length. The antibacterial emulsion (SAQx‐n) was synthesized by emulsion polymerization of styrene (St), butyl acrylate (BA), acrylic acid (AA) and MEQABr‐x(x = 12, 14, 16). The structures of its films (SAQx‐n‐F) were characterized by attenuated total reflectance‐FTIR. The effects of MEQABr‐14 content or alkyl chain length of MEQABr‐x(x = 12, 14, 16) on emulsion and its films were investigated in the aspect of particle sizes, pencil hardness, adhesive force grade, thermal stabilities, surface morphology, particle morphology, and so forth. The films (SAQx‐9‐F) with 9 wt% content of MEQABr‐x(x = 12, 14, 16) showed the nearly 100% antibacterial rate against Escherichia coli and Staphylococcus aureus, indicating its potential to be used as antibacterial coating.