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7,178 result(s) for "Emulsion polymerization"
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Organic Semiconductors Processed from Synthesis‐to‐Device in Water
Organic semiconductors (OSCs) promise to deliver next‐generation electronic and energy devices that are flexible, scalable and printable. Unfortunately, realizing this opportunity is hampered by increasing concerns about the use of volatile organic compounds (VOCs), particularly toxic halogenated solvents that are detrimental to the environment and human health. Here, a cradle‐to‐grave process is reported to achieve high performance p‐ and n‐type OSC devices based on indacenodithiophene and diketopyrrolopyrrole semiconducting polymers that utilizes aqueous‐processes, fewer steps, lower reaction temperatures, a significant reduction in VOCs (>99%) and avoids all halogenated solvents. The process involves an aqueous mini‐emulsion polymerization that generates a surfactant‐stabilized aqueous dispersion of OSC nanoparticles at sufficient concentration to permit direct aqueous processing into thin films for use in organic field‐effect transistors. Promisingly, the performance of these devices is comparable to those prepared using conventional synthesis and processing procedures optimized for large amounts of VOCs and halogenated solvents. Ultimately, the holistic approach reported addresses the environmental issues and enables a viable guideline for the delivery of future OSC devices using only aqueous media for synthesis, purification and thin‐film processing. An environmentally benign cradle‐to‐grave process from synthesis‐to‐device is demonstrated for high performance organic field‐effect transistors. This holistic approach uses aqueous processes from mini‐emulsion polymerization to purification and thin‐film deposition. Compared to conventional approaches, the process requires fewer steps, lower reaction temperatures, a significant reduction in the use of volatile organic compounds and avoids toxic halogenated solvents.
High molecular weight polyacrylamide nanoparticles prepared by inverse emulsion polymerization: reaction conditions-properties relationships
High molecular weight polyacrylamide (PAM) nanoparticle dispersions are products with wide application possibilities, the most important of which is in petroleum industry such as drilling fluid and flooding agent in enhanced oil recovery. For that aim, it is necessary to achieve complete control of the final dispersion and polymer properties during the synthesis step. In this work, PAMs were synthesized by inverse emulsion polymerization of aqueous acrylamide solution in cyclohexane in the presence of emulsifier mixture of Span 20 and Span 80. We present a comprehensive study of the effects of variation of all important reaction conditions (agitation rate, reaction time and temperature, initiator type and concentration, emulsifier HLB ratio and its concentration, and water to oil ratio) on final monomer conversion, reaction kinetics, polymer intrinsic viscosity and molecular weight, particle size and distribution, and colloidal stability. Finally, the relationships between the reaction conditions and the polymer properties were developed, which allowed determination of the ranges of variation of reaction conditions for optimal PAM properties for the oil industry applications: high molecular weight and intrinsic viscosity, nanosized polymer particles with narrow particle size distribution, and improved colloidal stability of the final dispersions.
Advances in Organic–Inorganic Hybrid Latex Particles via In Situ Emulsion Polymerization
Hybrid latex particles combine the unique properties of inorganic nano/micro particles with the inherent properties of polymers, exhibiting tremendous potential for a variety of applications. Recent years have witnessed an increased interest in the design and preparation of hybrid latex particles with well-defined size, structure and morphology. Due to its simplicity, versatility and environmental friendliness, the in situ (Pickering) emulsion polymerization has been demonstrated to be a powerful approach for the large-scale preparation of hybrid latex particles. In this review, the strategies and applications of in situ (Pickering) emulsion polymerization for the preparation of hybrid latex particles are systematically summarized. A particular focus is placed on the strategies for the preparation of hybrid latex particles with enhanced properties and well-defined core–shell, yolk–shell, multinuclear, raspberry-like, dumbbell-shaped, multipod-like or armored morphologies. We hope that the considerable advances, examples and principles presented in this review can motivate future contributions to provide a deeper understanding of current preparation technologies, develop new processes, and enable further exploitation of hybrid latex particles with outstanding characteristics and properties.
Preparation of HMX/PMMA Composite Microspheres with Excellent Properties by Photoinitiated Emulsion Polymerization
High-energy insensitive energetic materials are currently a research focus. Octogen (HMX) is one of the best-performing nitramine explosives, but its poor crystal morphology causes high mechanical sensitivity, limiting its application. This study proposed a method combining spheroidization, nanosizing, and coating desensitization. Nano-SiO and TiO were used to modify methyl methacrylate (MMA), and HMX/PMMA composite energetic microspheres were successfully prepared with the assistance of an ultraviolet (UV) lamp for catalytic polymerization. Molecular dynamics simulations determined the optimal particle ratios, and the effects of modifier content on morphology, crystal form, thermal stability, mechanical properties, and static mechanical properties were experimentally investigated. The prepared HMX/PMMA/modifier microspheres exhibited uniform size, dense structure, excellent performance, and ideal coating. Thermal decomposition kinetics showed that the activation energy of HMX/PMMA/SiO (0.75 wt% SiO ) increased by 79.86 kJ/mol and 27.55 kJ/mol compared with raw HMX and HMX/PMMA, respectively. Its impact sensitivity was 3.6 times that of raw HMX, and its friction sensitivity was twice that of raw HMX. Static mechanical analysis revealed that the compressive strength of HMX/PMMA/SiO (0.75 wt% SiO ) and HMX/PMMA/TiO (0.5 wt% TiO ) microspheres increased by 7.3 MPa and 6.1 MPa, respectively, over HMX/PMMA, indicating significant improvement. Overall, HMX/PMMA/SiO and HMX/PMMA/TiO microspheres prepared by photoinitiated emulsion polymerization exhibited excellent thermal stability and mechanical properties.
Synthesis of Janus Particles by Seeded Emulsion Polymerization
Janus particles (JPs), as a special material with anisotropic chemical or physical partitioning, show great potential for application in the fields of material science, biomedicine, energy, and environment. How to achieve fine structural control and large-scale synthesis of JPs is the key point and difficulty for JPs. Seeded emulsion polymerization, as a simple and efficient method, plays an important role in the controlled fabrication of JPs. Here, we provide a comprehensive review of the research progress in the preparation of JPs via seeded emulsion polymerization. We systematically summarize the process mechanisms and key parameters influencing the formation of Janus structures, with particular emphasis on the effects of seed characteristics, polymerization conditions, and component selection on particle morphology and anisotropy.
Synthesis of P(AM/AA/SSS/DMAAC-16) and Studying Its Performance as a Fracturing Thickener in Oilfields
In order to solve the problems of long dissolution and preparation time, cumbersome preparation, and easy moisture absorption and deterioration during storage or transportation, acrylamide (AM), acrylic acid (AA), sodium p-styrene sulfonate (SSS), and cetyl dimethylallyl ammonium chloride (DMAAC-16) were selected as raw materials, and the emulsion thickener P(AM/AA/SSS), which can be instantly dissolved in water and rapidly thickened, was prepared by the reversed-phase emulsion polymerization method. DMAAC-16, the influence of emulsifier dosage, oil–water ratio, monomer molar ratio, monomer dosage, aqueous pH, initiator dosage, reaction temperature, reaction time, and other factors on the experiment was explored by a single-factor experiment, and the optimal process was determined as follows: the oil–water volume ratio was 0.4, the emulsifier dosage was 7% of the oil phase mass, the initiator dosage was 0.03% of the total mass of the reaction system, the reaction time was 4 h, the reaction temperature was 50 °C, the aqueous pH was 6.5, and the monomer dosage was 30% of the total mass of the reaction system (monomeric molar ratio n(AM):n(AA):n(SSS):n(DMAAC-16) = 79.2:20:0.5:0.3). X-ray diffraction analysis (XRD), infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and scanning electron microscopy analysis were carried out on the polymerization products. At the same time, a series of performance test experiments such as thickening performance, temperature and shear resistance, salt resistance, sand suspension performance, core damage performance, and fracturing fluid flowback fluid reuse were carried out to evaluate the comprehensive effect and efficiency of the synthetic products, and the results show that the P(AM/AA/SSS/DMAAC-16) polymer had excellent solubility and excellent properties such as temperature and shear resistance.
Fabrication of Polyurethane–Polyacrylate Hybrid Latexes with High Organosilicon Content via Phase Inversion Emulsion Polymerization
Waterborne polyurethane, with a mechanical strength comparable to solvent-based types, is eco-friendly and safe, using water as a dispersion medium. Polyacrylate excels in film formation and weather resistance but suffers from “hot stickiness and cold brittleness”. Merging polyurethane and polyacrylate creates advanced hybrids, while organosilicon enhances properties but is restricted due to hydrolytic crosslinking. In this paper, a series of polyurethane–polyacrylate hybrid latexes with high organosilicon content were prepared using phase inversion emulsion polymerization technology. Even when the monomer content of 3-(methacryloyloxy)propyltrimethoxysilane (MPS) was increased to 10%, the polymerization process was stable, without the formation of a gel precipitate. The resulting latexes could remain stable for at least 6 months without significant changes in the properties of their films. The effects of MPS content on the mechanical and thermal properties of latex films were systematically researched. The study showed that with an increase in MPS dosage, the hardness and elastic modulus of the latex films increased, while the elongation at break and water absorption decreased, together with the increased glass transition temperature and surface hydrophilicity. This work aims to provide new theoretical guidance for the preparation of silicone-modified hybrid latexes, enabling their safe and stable production and storage.
Gradual Morphological Tuning in Polymer Microspheres via Pickering Emulsion Synthesis: Architecture-Controlled Dye Adsorption and Encapsulation
Polymeric microspheres synthesized via Pickering emulsion polymerization offer structural tunability, making them attractive platforms for dye adsorption. This study investigates the adsorption behavior of methylene blue onto two classes of polymeric microspheres—poly(methacrylic acid) crosslinked with ethylene glycol dimethacrylate (PM), containing both micro- and nanopores, and poly(methacrylic acid) crosslinked with divinylbenzene (PD), containing only nanopores. The adsorption kinetics were modeled using a dual-process approach that distinguishes between diffusion-controlled transport and surface-controlled kinetic adsorption. We quantified the relative contributions of these mechanisms and correlated them with particle architecture. In the PM particles, diffusion plays a significant role in smaller particles with larger macropores, enabling methylene blue to penetrate the interior. As the particle size increased and macroporosity decreased, adsorption becomes increasingly dominated by surface kinetics. In contrast, PD particles —which lack macropores—showed the opposite trend: smaller particles were primarily governed by fast surface adsorption, while in larger particles, diffusion through nanopores became increasingly relevant. Correlation analysis between adsorption rate constants and structural parameters such as particle diameter and pore sizes revealed strong, opposing trends. In PD particles, a near-perfect inverse correlation was observed between the diffusion and kinetic components, indicating competitive suppression, where the dominance of one mechanism limited the contribution of the other. These results demonstrated that internal pore architecture played a central role in controlling the adsorption mechanism. Tuning particle size and porosity allowed deliberate control over the balance between diffusion and surface kinetics, enabling the rational design of microparticle adsorbents with tailored uptake behavior for water purification and dye removal applications.
Hydrolytic Degradation of Porous Crosslinked Poly(ε-Caprolactone) Synthesized by High Internal Phase Emulsion Templating
Porous poly(ε-caprolactone) (PCL) scaffolds were fabricated using the high internal polymerization emulsion (HIPE) technique. Bis(ε-caprolactone-4-yl) (BCY) was utilized as crosslinker. The crosslinking density and the volume fraction of the dispersed phase were varied in order to study the potential effect of these parameters on the hydrolytic degradation at 37 °C and 60 °C. After different hydrolysis times the remaining solid samples were analyzed by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM), while the degradation products in the aqueous aging solutions were analyzed by laser desorption ionization-mass spectrometry (LDI-MS). The effect of temperature on the degradation process and release of degradation products was, as expected, significant. The temperature effect was also shown by FTIR analysis that displayed a pronounced increase in the intensity of the hydroxyl-group absorption band after 70 days of hydrolysis at 60 °C indicating significant cleavage of the polymer chains. LDI-MS analysis proved the release of oligomers ranging from dimers to hexamers. The product patterns were similar, but the relative m/z signal intensities increased with increasing time, temperature and crosslinking density, indicating larger amounts of released products. The latter is probably due to the decreasing degree of crystallinity as a function of amount of crosslinker. The porous structure and morphology of the scaffolds were lost during the aging. The higher the crosslinking density, the longer the scaffolds retained their original porous structure and morphology.
One-pot synthesis of organic-inorganic hybrid hollow latex particles via Pickering and seeded emulsion polymerizations
Hybrid hollow latex (HL) particles possessing poly(styrene- co -acrylic acid) (P(St/AA)) as the inner shell, poly(divinyl benzene) (PDVB) as the outer shell, and silica nanoparticles (SiNPs) as the stabilizer were conveniently prepared via the combined Pickering and seeded emulsion polymerizations. P(St/AA) particles (435 nm) were used as seeds, DVB as a swollen and crosslink monomer, 2,2′-azobis(2-methylpropionamidine) dihydrochloride as initiator, and SiNPs as Pickering stabilizer. Without core removal, solvent evaporation, and surface modification steps, the spherical, monodisperse, and non-collapsed HL-SiNPs particles (722 nm) with double shell polymer layer and a large void cavity (400 nm) were obtained. The presence of large cavity and double shell may enable these hybrid HL-SiNPs particles to be used as lightweight filler and/or white pigment in coatings.