Particle Nucleation Using Different Initiators in the Miniemulsion Polymerization of Styrene

Ronco, Ludmila Irene; Minari, Roque Javier; Gugliotta, Luis Marcelino

doi:10.1590/0104-6632.20150321s00003150

Cited by 19 publications

(20 citation statements)

References 23 publications

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“…The solubility of the initiator also affects the properties of the resulting particles as it governs where the initiator radicals are generated [4, 7]. M2 and M4 particles, made via emulsion polymerisation and surfactant-free emulsion polymerisation, respectively, have water-soluble initiators which decompose in the water phase before entering the monomer micelles.…”

Section: Resultsmentioning

confidence: 99%

“…Firstly, the initiator is responsible for functional groups on the particles. During polymerisation, free radicals from the initiator become incorporated into the end groups of the polymer chains and hence any functional or polar groups on the initiators will lead to functionalized or polar particles [4–6]. Nair [5] made microgel particles using two different initiators, 4,4 ′ -azobis(4-cyanovaleric acid) (ACVA) and potassium persulfate (KPS) and found that particles made with ACVA could be redispersed in low polarity solvents, whereas KPS particles could only be redispersed in higher polarity solvents.…”

Section: Introductionmentioning

confidence: 99%

“…The solubility of the produced initiator radicals also affects the particle properties as it determines where the polymerisation occurs and where on the particle the functional groups will reside [4, 7]. If the particle surface is covered in functional polar groups from the initiator molecules, then the overall particle dispersibility will be affected whereas, if the initiator molecules are hidden within the particles, then the particle dispersibility will be less dependent on the initiator functionality.…”

Section: Introductionmentioning

confidence: 99%

“…Mori and Kawaguchi [7] made magnetic polymer particles using a miniemulsion polymerisation and found that both the size of the particles and the location of the magnetite depended on the solubility of initiator used [7]. The polymerisation kinetics, droplet nucleation mechanism [4] and interactions with surfactants [6] are also affected by the type of initiator.…”

Section: Introductionmentioning

confidence: 99%

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The role of initiator on the dispersibility of polystyrene microgels in non-aqueous solvents

et al. 2017

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Non-aqueous microgel particles are commonly synthesised in water, dried, and then redispersed in non-aqueous solvents. An important factor to consider when synthesising such particles is the initiator, which can determine how well the particles disperse in solvents. Polystyrene microgel particles were made with three different initiators. When a neutral, oil soluble initiator (azobisisobutyronitrile) was used the particles dispersed in toluene as well as cyclohexane and decalin. In contrast, anionic, water-soluble initiators (potassium persulfate or azobis(4-cyanovaleric acid)) created particles that only redispersed in toluene and not the other two solvents. Of the three considered, toluene is the best solvent for polystyrene and also has the highest polarizability, making it most effective at redispersing particles with polar or ionisable functional groups. Zeta potential and conductivity measurements, however, did not detect a direct relationship between particle charging and redispersibility. Oil soluble initiators result in “inside out” polymerisation where the initiator groups are buried inside the growing particle, whereas water-soluble initiators result in “outside in” polymerisation, with the polar initiator groups residing on the particle surface. By tailoring the ratio between water and oil soluble initiators, it may be possible to synthesise microgel particles with uniform or designed charge profiles from the core to the surface.Electronic supplementary materialThe online version of this article (doi:10.1007/s00396-017-4023-y) contains supplementary material, which is available to authorized users.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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The role of initiator on the dispersibility of polystyrene microgels in non-aqueous solvents

et al. 2017

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“…Similar results have been reported in the literature. [7] The monitoring of droplet/particle size during the miniemulsion polymerization process would allow to detect and quantify these changes, thus shedding light on the possible nucleation phenomena that are effective under these conditions. Spectroscopic techniques such as NIR (near-infrared) and Raman spectroscopy have been shown to be very effective for monitoring different chemical and polymerization processes.…”

Section: Introductionmentioning

confidence: 99%

Miniemulsion Polymerization Monitoring Using Off‐Line Raman Spectroscopy and In‐Line NIR Spectroscopy

Ambrogi

Colmán

Giudici

2016

Macro Reaction Engineering

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by water-borne latex, increasing the importance of conventional emulsion and miniemulsion polymerization.In comparison with conventional emulsion polymerization processes, miniemulsion polymerization presents clear advantages because polymerization takes place inside the monomer droplets, which allows using monomers and other highly hydrophobic components in the formulation. Therefore, these components do not need to diffuse in the aqueous medium as in emulsion polymerization. [1][2][3][4] The miniemulsion polymerization process starts with the preparation of the monomer miniemulsion and, after that, the addition of an initiator starts the polymerization. A standard miniemulsion formulation uses water as continuous phase, monomer as disperse phase, surfactant to stabilize the particles droplets, costabilizer to avoid diffusional degradation (Oswald Ripening), and buffer to stabilize the pH of the medium. [5] Constant particle size, use of costabilizers, use of surfactant below the critical micellar concentration, and inexistence of mass transport through the aqueous phase are Miniemulsion polymerization has been extensively studied in the last decade due to its advantages when compared with conventional emulsion polymerization. In this work, monomer conversion and particle size are monitored during miniemulsion polymerization of styrene using in-line near-infrared (NIR) spectroscopy and at-line Raman spectroscopy. Gravimetric analysis and dynamic light scattering have been used as off-line reference measurements. Good agreement has been found between off-line data and the values predicted by NIR and Raman spectroscopy for conversion. The values of average particle size are well predicted from the NIR spectra with the respective calibration model, but the predictions from Raman spectra present some slight discrepancies for particle size. The results show a decrease of the average particle size during the initial period of the polymerization, indicating the occurrence of nucleation mechanisms other than the classical droplet nucleation. These results indicate that insightful information can be obtained by monitoring miniemulsion polymerizations with the use of spectroscopic techniques.

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Preparation of Thermochromic Films from Latexes Made by Miniemulsion Polymerization

Colmán

Valdez

George

et al. 2019

Macro Reaction Engineering

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The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/mren.201900009. Thermochromic FilmsThermosensitive-thermochromic pigments are classified as smart materials capable of detecting and/or responding to environmental stimuli, and specifically in this study, changes in temperature that induce a change in the color of the material. This study aims to obtain nanoparticles of poly(styrene-co-butyl acrylate) and poly(styrene-co-methyl methacrylate), containing thermosensitivethermochromic pigments that are incorporated into the monomer droplets in miniemulsion polymerization. Miniemulsion polymerization has the advantage that the pigment particles can be dispersed directly in the monomer droplets and are encapsulated when the miniemulsion droplets are polymerized. Using controlled/living radical polymerization (or Reversible Deactivation Radical Polymerization), it is possible to produce polymers with better control of microstructure and narrower molecular weight distributions. Nitroxide-mediated polymerization (NMP) is conducted using the BlocBuilder initiator, as well as a conventional free radical polymerization (FRP) using potassium persulfate (KPS) and 2,2-azobis(2-methylpropionitrile) (AIBN). Stable latexes containing the thermosensitive-thermochromic pigments are obtained by both NMP and FRP. Films are made from the latexes and shown to exhibit thermochromic behavior.

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Particle Nucleation Using Different Initiators in the Miniemulsion Polymerization of Styrene

Cited by 19 publications

References 23 publications

The role of initiator on the dispersibility of polystyrene microgels in non-aqueous solvents

The role of initiator on the dispersibility of polystyrene microgels in non-aqueous solvents

Miniemulsion Polymerization Monitoring Using Off‐Line Raman Spectroscopy and In‐Line NIR Spectroscopy

Preparation of Thermochromic Films from Latexes Made by Miniemulsion Polymerization

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