Morphology Of Composite Particles Research Articles

Designing an optimised formulation for in situ emulsion polymerization: printing ink production by response surface methodology

Purpose Toner is a crucial dry colorant composite used in printing based on the electrophotographic process. The quality of printed images is greatly influenced by the toner production method and material formulation. Chemically in situ polymerization methods are currently preferred. This paper aims to optimize the characteristics of a composite produced through emulsion polymerization using common raw materials for electrophotographic toner production. Design/methodology/approach Emulsion polymerization provides the possibility to optimize the physical and color properties of the final products. Response surface methodology (RSM) was used to optimize variables affecting particle size (PS), PS distribution (PSD), glass transition temperature (Tg°C), color properties (ΔE) and monomer conversion. Box–Behnken experimental design with three levels of styrene and butyl acrylate monomer ratios, carbon black pigment and sodium dodecyl sulfate surfactant was used for RSM optimization. Additionally, thermogravimetric analysis and surface morphology of composite particles were examined. Findings The results indicated that colorants with small PS, narrow PSDs, spherical shape morphology, acceptable thermal and color properties and a high percentage of conversion could be easily prepared by optimization of material parameters in this method. The anticipated outcome of the present inquiry holds promise as a guiding beacon toward the realization of electrographic toner of superior quality and exceptional efficacy, a vital factor for streamlined mass production. Originality/value To the best of the authors’ knowledge, for the first time, material parameters were evaluated to determine their impact on the characteristics of emulsion polymerized toner composites.

Synthesis a Clay Based Photocatalyst for the Removal of Eosin Yellow in Aqueous Solution

Composite photocatalysts of clay and ZnO have been prepared using three different compositions and characterized by various techniques such as SEM, EDX, FTIR, and XRD. SEM micrographs in different magnifications revealed different morphology of composite particles rather than commercial ZnO and clay. The particle size of the prepared composite decreased with the increasing amount of clay and thus improves the catalyst surface area. EDX revealed that the composite contains clay and ZnO only. According to FTIR spectrum data, when the ratios of clay to ZnO are 12:88 and 25:75, all the clay particles are completely covered. The shift in the peak position of XRD patterns indicates the molecular level interaction between clay and ZnO. The composite photocatalyst with a composition of clay: ZnO = 25:75 has the highest capability to eliminate Eosin Yellow (EY) by both adsorption and photodegradation among the tested composite photocatalysts. At this composition, the degrading rate of 0.2 g of material in a 2×10-5 M aqueous solution was around 44.48% EY. However, after 60 minutes of photodegradation using UV light, the entire elimination of dye, including adsorption and photodegradation, is around 68.32%. As the concentration of EY increased, the degradation rate of EY reduced. It was discovered that the consequences of HCO3-, CO32-, Cl-, NO3-, and SO42- ions were deleterious to the photodegradation of EY. It was also discovered that the UV source was more effective than the visible source. An intense UV light causes EY to completely degrade.

Polysilsesquioxane precursors stabilizing chlorotrifluoroethylene copolymerization for waterborne hybrid fluorocarbon coatings with excellent synergistic performances

An environmentally friendly, low-cost and simple method to prepare poly(tert-butyl acrylate)/poly(chlorotrifluoroethylene-co-isobutyl vinyl ether)/polysilsesquioxane (PtBA/P(CTFE-co-IBVE)/PSQ) organic–inorganic hybrid waterborne fluorocarbon coatings is reported in this article. It is worth mentioning that the PSQ precursors are used as the only stabilizer of emulsion system owing to their amphiphilicity presented after hydrolysis. The composition and morphology of composite particles, microscopic phase separation and comprehensive properties of the latex coatings are further investigated. The results show that PSQ precursor not only plays the role of emulsion stabilizer, but also improves the thermal stability and hydrophobicity of the coatings. Furthermore, the influences of MPS addition amount and flexible chain segments content on organic–inorganic phase separation and coating transparency are systematically studied to address the main challenge that organic–inorganic hybrid coatings are facing, namely, how to ensure the addition of PSQ and CTFE can endow the coating with both inherent advantages without compromising other properties such as transparency, adhesion, etc. Finally, the prepared waterborne coatings exhibit strong adhesion, excellent UV resistance and outstanding organic solvents resistance under the synergistic effect between the coating components. The understanding of PtBA/P(CTFE-co-IBVE)/PSQ composite system will be of great help to design & fabricate better hybrid waterborne fluorocarbon coatings in the future.

Characterization of solid-electrolyte/active-material composite particles with different surface morphologies for all-solid-state batteries

In all-solid-state lithium-ion batteries (ASS-LIBs), the electrode structure is an important factor that determines the battery performance; in particular, the formation of contact interface between the active material (AM) and solid electrolyte (SE) is an important issue associated with ASS-LIBs. Although we previously reported the formation of interfacial contacts between AM and SE by dry coating, the influence of the surface morphologies of composite particles on the performance of ASS-LIB was not revealed. In this study, we investigated the effects of the surface morphologies of composite particles on the performance of ASS-LIB. The surface morphologies of composite particles changed from “discrete” to “continuous” as the dry coating progressed. The cell prepared with composite particles showed higher ionic conductivity due to well-percolated ionic path than that prepared with simple mixture. Comparing the composite particles with different surface morphologies, the cell prepared with discrete-coating particles showed lower internal resistance due to higher ionic/electrical conductivity than that prepared with continuous-coating particles. Further, the cells prepared with discrete- and continuous-coating particles showed the highest charge and discharge capabilities, respectively. The results suggest that the contact areas of AM-SE and AM-AM were critical structural factors for the discharge and charge rate capability, respectively.

Preparation and Morphology Control of Poly(ionic liquid) Particles.

Poly(ionic liquid)s (PILs) are prepared by the polymerization of ionic liquid (IL) monomers that have polymerizable groups on their cationic or anionic component. PILs also share many of the characteristic properties of ILs and can be used in various materials such as CO2 sorbents, polymer electrolytes, dispersants, and microwave-absorbing materials. In this feature article, we survey our research, focusing on the preparation of PILs in the particulate state (PIL particles) and on the morphological control of the PIL particles, including (1) the preparation of PIL particles by dispersion polymerization and emulsion polymerization, (2) control of the morphology of composite particles consisting of a PIL and poly(methyl methacrylate) (PMMA), (3) the preparation of hollow particles with a PIL shell, and (4) the preparation of PIL particles containing reduced graphene oxide (rGO). The size of the obtained PIL particles could be controlled through a modification of the synthesis conditions and the mode of polymerization (i.e., dispersion polymerization or emulsion polymerization). The obtained PIL particles maintained the characteristic properties of the corresponding ILs; moreover, the solubility of the PIL particles could be easily modified by changing their counteranion. Using seeded polymerization, we prepared PMMA/PIL composite polymer particles and subsequently demonstrated that their morphology can be manipulated to yield a core-shell or Janus structure. Hollow particles consisting of a PIL shell were also prepared, and modification of the polarity and penetration behavior of the shell through anion exchange was demonstrated.

Preparation of Janus Particles Composed of Hydrophobic and Hydrophilic Polymers

Composite particles were prepared by the seeded polymerization of an ionic liquid monomer ([2-(methacryloyloxy)ethyl]trimethylammonium bis(trifluoromethanesulfonyl)amide) ([MTMA][TFSA]) in the presence of poly(methyl methacrylate) (PMMA) particles. The obtained particles have a core–shell morphology: PMMA core and P([MTMA][TFSA]) shell. To change the composite particle morphology from core–shell to Janus, we used the solvent-absorbing/releasing method with methyl isobutyl ketone, which is a suitable solvent for PMMA and P([MTMA][TFSA]) with nonionic surfactants (polyoxyethylene nonylphenyl ether, Emulgen 950) and Li[TFSA]. Based on the ultrathin cross-section observations, we found the core–shell PMMA/P([MTMA][TFSA]) composite particle morphology changed to a Janus structure. Moreover, anion exchange occurred in the obtained Janus particles. When using LiBr, we obtained PMMA hemisphere particles because of the changes in the PIL hemisphere polarity via anion exchange and dissolution in water. On the contr...

Estimation of Copolymer/Water Interfacial Tensions Using Pendant Drop Tensiometry.

Copolymer/water interfacial tensions of statistical copolymers of styrene/ n-butyl acrylate were estimated by pendant drop tensiometry using an "inverse" configuration according to which a drop of water was formed in toluene/copolymer solutions. The study first involved the precise measurement of copolymer solutions density using pycnometry. Subsequently, interfacial tensions of copolymer solutions against water were plotted as a function of copolymer concentration in toluene. Several methods were explored to fit the experimental data and obtain estimates of copolymer/water interfacial tensions at 100% copolymer concentration in toluene by extrapolation. The Belton-Evans extrapolation resulted in the best fit with the experimental data. When plotted as a function of the styrene composition of the copolymer, the interfacial tensions estimates followed an additivity relationship. This enabled estimation of the copolymer/water interfacial tensions directly from their respective homopolymer/water interfacial tensions values. These results are particularly useful for the prediction of composite particle morphology involving copolymerization of multiple monomers.

Fabrication of shape-tunable macroparticles by seeded polymerization of styrene using non-cross-linked starch-based seed

Nonspherical colloidal particles with various geometries and different compositions have attracted tremendous attention and been widely researched. The preparation of polymer colloidal particles with controlled shapes by seeded polymerization is recognized as the most promising technique owing to the precise control of various morphologies and using non-cross-linked seed particles are of particular interest. Seeds particles derived from natural biopolymers are seldom applied. Hence, non-cross-linked starch-based seed could be used to fabricate the anisotropic particles by soap-free seed polymerization.Non-cross-linked starch-based seed particles were prepared by a nanoprecipitation method. Starch/polystyrene composite colloidal particles with shape-tunable were fabricated by soap-free seeded polymerization using starch-based seed. The effect of the polymerization time, monomer feed ratio and seed type were investigated.The seed particles with a single- or multi-hole structure were obtained after swelling with styrene. The resulting particles including golf-like, raspberry-like, octahedron-like and snowman-like structures, was fabricated on the polymerization process. This study firstly reports that the morphology of composite particles from golf-like to snowman-like at high monomer feed ratio using starch-based seed. At low monomer feed ratio, raspberry-like particles were obtained by surface nucleation increasing process. In addition, seed type also effect the morphology of composite particles.

Controllable synthesis of anisotropic silica/polymer composite particles via seeded dispersion polymerization

In this work, seeded dispersion polymerization was adopted to prepare anisotropic silica/polymer composite particles with controllable sizes and morphologies using the surface-modified silica particles as the seeds. Through this approach, submicron-sized silica/polymer particles with snowman-like, dumbbell-like, raspberry-like and core-shell structures could be easily fabricated in large scale. Many factors that might affect the morphologies of composite particles including the weight ratio of monomer/silica seeds, the polarity of reaction medium, reaction temperature, reaction time, the amount of crosslinking agent or the polarity of monomers were investigated. The results indicate that the interfacial tension between PS phases and SiO2 particles and the coalescence between growing polymer nodules over silica particles are responsible for the formation of different particle morphologies. It is interesting that snowman-like SiO2/PS particles could be afforded by two different processes: one was normally transformed from raspberry-like particles via the coalescence between growing polymer nodules; the other was formed directly at a high content of monomer. These different morphological particles may have important applications in biological/medical materials, optical materials, sensors, catalyst support, colloidal stabilizer, etc.

Synthesis of micron-sized porous CeO2[sbnd]SiO2 composite particles for ultraviolet absorption

Micron-sized porous composite particles composed of CeO2 and SiO2 nanoparticles were prepared for a UV absorption application by an aerosol spray-drying process from as-prepared CeO2 nanoparticles, commercial SiO2, and a polystyrene latex template. The morphology, structure crystallinity and pore size distribution of the as-prepared porous CeO2SiO2 composite particles were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Barrett-Joyner-Halenda (BJH) method, respectively. The porous CeO2SiO2 composite particles, with diameters of approximately 10μm, showed a spherical morphology. As the contents of CeO2 in the precursor was increased from 0.25wt% to 1.5wt%, we observed a change in the morphology of the composite particles from compactly packed porous particles to loosely packed porous particles. The as-prepared CeO2SiO2 composite particles were composed of meso- and macropores in the range of 3–200nm. The effect of the CeO2 content on the porous composite particles in terms of the UV absorption properties was also investigated by UV-visible spectroscopy. When the content of CeO2 exceeded 0.75wt% in the precursor, the particles showed higher UV absorption values compared to those of commercial TiO2 nanoparticles. The as-prepared porous CeO2SiO2 composite particles can therefore be promising materials given their high UV absorption value.

Preparation of nano‐encapsulated polyethylene wax particles for color toner by in situ emulsion polymerization

ABSTRACTPolystyrene‐acrylate resin coated polyethylene (PE) wax composite particles used for color toner were prepared by in situ emulsion polymerization. The laser particle analyzer and transmission electron microscope (TEM) were applied to show the size and morphology of composite particles, and thermogravimetric analysis (TGA) was used to characterize the thermal properties of the nanoparticles. With the increase of emulsifier triton x‐100 (TX‐100), the size of composite particles decreased at first and then increased and the shell thickness increased gradually. When the mass ratio of TX‐100 to monomers was 1:10, the core–shell structure of the latex particles was the clearest. The homopolymer of styrene (St) and copolymer of styrene‐butyl acrylate (St‐BA) showed few differences on the size of the composite particles, but a significant difference on the thermal performance. The FTIR spectra and dissolution experiments of PE wax/P(St‐BA) composite particles provided supporting evidence for encapsulation. With the increasing percentage of polyethylene wax, the particles size got larger and emulsion shelf stability became worse. The size and the shelf stability got optimized when the reaction temperature was 80 °C. The average size of the particles initiated by 2,2‐azobisisobutyronitrile (AIBN) was smaller and the size distribution was narrower than those of initiated by potassium persulfate (KPS). © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44399.

A new approach for mathematical modeling of the dynamic development of particle morphology

A new model for the dynamic evolution of the morphology of polymer-polymer latex particles has been developed. This model overcomes the limitations of the existing methodologies that were only able to provide the morphology of a single particle, which is only a restricted view of the real system that contains a distribution of particle morphologies. Taking into account the relevant kinetic and thermodynamic effects, the new model calculates the distribution of morphologies for the whole population of polymer particles with less computational effort than that needed by the previous models to calculate the morphology of a single particle. The model was validated by fitting the evolution of particle morphology of composite particles during polymerization of methyl methacrylate on a polystyrene seed. Furthermore, the ability of the model to predict the evolution of the particle morphology for different cases was explored.

Methanol vapor sensor based on poly(styrene-co-butylacrylate)/polypyrrole-EG core–shell nanocomposites

Poly(styrene-co-butylacrylate)/polypyrrole-expanded graphite (EG) core–shell nanocomposites were synthesized by mini-emulsion polymerization. The particles were characterized by FT-IR, SEM, EDX, TEM and I–V analysis. TEM and SEM analysis reveals core–shell morphology of composite particles. Composite particles show higher dc-electrical conductivity compared to bare PSBA/PPy core–shell nanocomposites. The responsive capability of the nanocomposites towards methanol vapor was systematically investigated using a simple two probe configuration. The core–shell particles could detect methanol vapor of 100ppm concentration with good response and recovery time.

Weak acid–base interaction induced assembly for the formation of berry-like polystyrene/SiO2 composite particles

To investigate the formation mechanism of berry-like polystyrene/silica (PS/SiO2) with carboxyl-functional templates through in-situ sol–gel process, different alkalis were adopted to catalyze the hydrolysis reaction of tetraethoxysilane (TEOS) and the morphology of composite particles was observed by TEM. The results showed that the weak acid–base interaction (–COO−/–N+/–SiO−) drove the silica particle nucleated and growth on the surface of PS spheres and berry-like structure can be easily adjusted by alkalis and volume ratio of ethanol/water. The present work implied that the weak acid–base interaction can be used to control the nano/micro or hierarchically structures. In addition, the particulate films were constructed by assembling these berry-like particles on the glass substrates. After surface modification with dodecyltrichlorosilane, hydrophobic surface can be obtained and the contact angle of water on the dual-sized structured surface can be adjusted.

Preparation and characterization of silica/polypyrrole core‐shell colloidal particles in the presence of ethanol as the cosolvent

AbstractThe silica/polypyrrole core‐shell composites were fabricated by in situ chemical polymerization of pyrrole monomer on the surface of the silica spheres. Silica sol particles with narrow size distributions were prepared by hydrolysis of tetraethoxysilane with sol–gel method. Polypyrrole shell was obtained by chemical polymerization of pyrrole monomer on the surface of the silica spheres in the water–ethanol mixture. It can be seen from the experiment, with the adding of small amount of ethanol cosolvent to the aqueous reaction solution, a uniform coating of polypyrrole appeared on the surface of silica. The core‐shell morphology of composite particles prepared with variation ethanol adding amount was analyzed by TEM. Meanwhile, the conductivity of the core‐shell composite is found to be enhanced apparently compared with those prepared from pure aqueous system. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Morphology of composite particles of single wall carbon nanotubes/biodegradable polyhydroxyalkanoates prepared by spray drying

Spray drying was investigated as a strategy for producing single wall carbon nanotube (SWCNT)/polymer composites. The spray-drying method produced SWCNT/poly(3-hydroxybutyrate) and SWCNT/poly(3-hydroxyoctanoate) composite particles in which the SWCNTs have been trapped in a well-dispersed state throughout the polymer matrix. Increasing SWCNT content in the composite led to a change in particle morphology from spherical and smooth to rosette shape with angular distortions. The technique shows potential for bulk carbon composite fabrication.

Manipulation of process parameters to achieve different ternary phase microparticle configurations

Ternary phase microparticles of poly( d, l-lactide-co-glycolide) (50:50), poly( l-lactide) and poly(caprolactone) were fabricated through a one-step solvent evaporation technique. The purpose of this study was to examine the effects of various process parameters on the final configuration (i.e. polymer distribution and dimensions) of these composite microparticles and, subsequently, propose their mechanism of formation. Particle morphologies and configurations were determined using scanning electron microscopy, polymer dissolution tests and Raman mapping. It was found that a starting polymer solution prepared below the cloud point and an increased oil to water ratio will facilitate polymer configurations close to thermodynamic equilibrium, which is dictated by the interfacial energies of the components. By varying the polymer mass ratio or adjusting the precipitation rate, through stirring speed and oil to water ratio, a wide range of microparticles with different core–shell dimensions and embedded particulate sizes can also be fabricated. At the same time, lowering the polymer solution concentration and increasing the stirring speed may result in smaller microparticles. Correlation of these process parameters with the final composite particle morphology was thus established. This understanding should allow the controlled fabrication of ternary phase composite microparticles through a single step solvent evaporation technique.

Gradient distribution of fluorine on the film surface of the organic–inorganic hybrid fluoropolymer

Inorganic–organic hybrid latex containing fluoride has been prepared in multistage emulsion polymerization in the presence of nano-SiO 2 particles and alkoxysilane (γ-methacryloxypropyltri(isopropoxy)silane, MAPTIPS). The effects of fluoride and alkoxysilane on the morphologies of composite particles were observed and it was found that the encapsulation may be fulfilled in the presence of dodecafluoroheptyl methacrylate together with MAPTIPS whether using raw SiO 2 particles or modified. The distribution of fluorine in different latex films was measured by X-ray photoelectron spectroscopy. It was indicated that the gradient distribution of fluorine from depth profile in the films may be enhanced by MAPTIPS and encapsulated SiO 2 due to the bidirectional move of MAPTIPS and congregation of SiO 2 on the film surface. Combining the results of XPS with AFM analysis, it was showed that the phase separation between organic and inorganic for encapsulated SiO 2 was lightened, while it was so apparent for raw SiO 2 that the orientation to the surface of fluorine was restrained in the lack of MAPTIPS.

Nucleation mechanism and morphology of polystyrene/Fe3O4 latex particles via miniemulsion polymerization using AIBN as initiator

AbstractIn this study, oil‐based magnetic Fe3O4 nanoparticles were first synthesized by a coprecipitation method followed by a surface modification using lauric acid. Polystyrene/Fe3O4 composite particles were then prepared via miniemulsion polymerization method using styrene as monomer, 2,2′‐azobisisobutyronitrile (AIBN) as initiator, sodium dodecyl sulfate (SDS) as surfactant, hexadecane (HD) or sorbitan monolaurate (Span20®) as costabilizer in the presence of Fe3O4 nanoparticles. The effects of Fe3O4 content, costabilizer, homogenization energy during ultrasonication, and surfactant concentration on the polymerization kinetics (e.g., conversion), nucleation mechanism, and morphology (e.g., size distributions of droplets and latex) of composite particles were investigated. The results showed that at high homogenization energy, an optimum amount of SDS and hydrophobic costabilizer was needed to obtain composite particles nucleated predominately by droplet nucleation mechanism. The morphology of the composite particles can be well controlled by the homogenization energy and the hydrophobicity of the costabilizer. The magnetic composite particles can be made by locating Fe3O4 inside the latex particles or forming a shell layer on their PS core surface depending on the aforementioned polymerization conditions. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Synthesis of composite particles through emulsion polymerization based on silica/fluoroacrylate-siloxane using anionic reactive and nonionic surfactants

The composite particles with core/shell structure resulting from the combination of silica seed and hydrophobic copolymer (dodecafluoroheptyl methacrylate (DFMA), γ-methacryloxypropyltriisopropoxidesilane (MAPTIPS), methyl methacrylate, butyl acrylate) were synthesized by emulsion polymerization. The amount of the silica seeds, concentration of reactive surfactant, as well as the addition of DFMA and MAPTIPS, have strong influences on the morphology of composite particles. It has been shown that it would be possible to produce stable organic/inorganic composite particles with inhomogeneous core/shell structure encapsulated by hydrophobic fluorinated acrylate even though using unmodified silica particles and admixture of anionic and nonionic surfactants. However, there was an obvious difference on the morphologies of core–shell structure whether the DFMA and MAPTIPS were added or not. It was concluded that two kinds of polymerization approaches might coexist in the presence of DFMA and MAPTIPS for raw silica. One clear advantage of this process is that there is only one silica bead for each composite particle. This kind of stable core–shell structural hybrid latex is useful for preparing high performance hydrophobic coating.