Surfactant-free emulsion

B.P. Binks and S.O. Lumsdon Influence of Particle Wettability on the Type and Stability of Surfactant-Free Emulsions. Langmuir 16, 8622 (2000). 

R.M. Pashley Effect of Degassing on the Eormation and Stability of Surfactant-Free Emulsions and Eine Teflon Dispersions. J. Phys. Chem. B 107, 1714 (2003). 

B. P. Binks and S. O. Lumsdon, Influence of particle wettability on the type and stability of surfactant-free emulsions, Langmuir 16, 8622-8631 (2000). 

Organic syntheses, which are usually activated by heat or light, for example, have found an excellent energy source for the acceleration and (or) activation in ultrasound. This application of US has been the subject of specialist books [37,38] or chapters thereof [39]. One case in point is the mediated electrosynthesis of carbon-carbon bonds in totally green surfactant-free emulsion media generated by the application of power ultrasound to a two-phase water-organic medium [40]. The authors called these immiscible media erroneously as mixtures . 

Fig. 5 Hydrogel-coated gold nanoparticles prepared by surfactant-free emulsion polymerization. After coating oleic acids on the gold nanoparticle, polymerization was carried out in the presence of A-isopropylacrylamide, acrylic acid, and ammonium persulfate (initiator). The size of resulting nanoparticles was in the range of 100-230 nm. (Modified from Ref l)...

It is not always necessary to use the stabilizing surfactant with surfactant free emulsion polymerization reported by Goodwin et al.. The particles are stabilized by the surface charge on the particles resulting from fragments of the initiator used. In these cases, the monomer concentration needs to be drastically reduced to less than 5%, and particle sizes of between 100 and 1000 nm are reported. 

Remarkable ordering is possible with highly monodisperse particles. This is demonstrated in Fig. 3, an SEM image of 200 nm radius polystyrene particles that were prepared by surfactant free emulsion polymerization. 

Fig. 7 Mobility versus pH data for polystyrene particles in 1 mM NaCl. The particles were made by surfactant free emulsion polymerization with 2,2-azo-bis(2-methylpropion amidine) dihydrochloride as the initiator.

Ceska GW. The effect of carboxylic monomers on surfactant-free emulsion copolymerization. J Appl Polym Sci 1974 18 427—437. 

Apparent BET surface areas for hypercrosslinked polystyrenic materials can be as high as 2,090 m g in some cases [25] and these materials can be produced as monoliths, powders, suspension polymerized beads, or by surfactant-free emulsion polymerization as spherical particles with diameters of around 500 nm [35]. Some care must be exercised when interpreting gas sorption isotherms for HCPs using sorbates such as nitrogen and argon as they exist in a non-classical [38] physical state and can exhibit unusual swelling characteristics (Fig. 3). 

R. M. Pashley, Effect of degassing on the formation and stability of surfactant-free emulsions and fine teflon dispersions, J. Phys. Chem. B, 2003, 107, 1714—1720. 

Many investigators have studied polymer surfaces for years [74,75] and have been successful in determining combinations of two or more valence states [76,77] by the mathematical process of deconvoluting the peak assignments [78]. It was only recently that latexes were examined by ESCA. Davies et al. [79] prepared a series of homopolymers of poly(methyl methacrylate) (PMMA) and poly(butyl methacrylate) (PBMA), and also poly[(methyl methacrylate)-co-(butyl methacrylate)] (PMMA-PBMA), by surfactant-free emulsion polymerization. It was found that the surface of the latex film was rich in PMMA, which may possibly be explained by the reactivity ratios for the MMA/BMA system (ri = 0.52 and rj = 2.11) [80], Recently, Arora et al. carried out angle-dependent ESCA studies on a series of films prepared from core-shell ionomeric latexes (with a polystyrene core and a styrene/n-butyl acrylate/ methacrylic acid copolymer shell) to determine the distribution of carboxyl groups in the films [81,82]. 

Badran et al. [4] explored the effects of otho- bisulfite adducts with potassium persulfate through the addition of sodium bisulfite to the carbonyl functionality on boizaldehyde, acetaldehyde, octyl aldehyde, methyl propyl keteme and acetone. The rate of polymerization, Rp, in the presence of these bisulfite adducts was a function of initiahn ctHicentration, [I], to the 0.54,0.66,0.95,1.0, and 1.1 powers reqrectivefy for surfactant-free emulsion polymerization at 40 °C where ... 

Sheibat-Othman N, Bourgeat-Lami E (2009) Use of siUca particles for the formation of organic-inorganic particles by surfactant-free emulsion polymerization. Langmuir 25(17) 10121-10133... 

Using a similar procedure, smaller magnetic particles (400-700 nm in diameter) were produced by Lindlar et al. [175], Polymer particles of poly(MMA-co-GMA) were first synthesized by surfactant-free emulsion polymerization. Ethylene diamine, was then the added to obtain internal anchor groups able to favor the subsequent impregnation and hydrolysis of iron salts inside the particles. The final composite particles were monodisperse in size and the magnetic loading was close to 25 wt%. 

Another strategy consists in the use of QDs coated with a cysteine acrylamide, a polymerizable stabilizer [304]. Successful incorporation of hydrophilic cysteine-acrylamide-stabilized QDs into 80-200 nm fluorescent latexes was achieved via emulsion polymerization, as reported by Sherman et al. [308], using two different procedures. In the first, a two-step shot growth surfactant-free emulsion polymerization of styrene and NaSS was performed in the presence of a solution of hydrophilic cysteine-acrylamide-stabilized CdS or CdSe/CdS QDs. In the second approach, CdSe/CdS QDs were first electrostatically modified by vinylbenzyl(trimethyl)-ammonium chloride and subsequently copolymerized with styrene in the presence of SDS. A third approach was also described in this paper coating of cationic PS particles with anionic poly(cysteine acrylamide)-coated QDs through electrostatic-driven interactions. 

Particles of poly(styrene-co-DMAEMA) have also been reported for the effective synthesis of luminescent CdS/polymer composite particles [320], The difference in this case was that surfactant-free emulsion copolymerization was performed in the presence of Cd + ions that were coordinated to DMAEMA. 

Fig. 16 Overall conversion versus (a) time and (b) number-average molar mass, M , and poly-dispersity index, A/w/Afn (the line represents the theoretical M ) for the nitroxide-mediated surfactant-free emulsion copolymerizations of methyl methacrylate and styrene in the presence of poly(PEGMA-ct>-MAA-co-styrene)-SGl macroalkoxyamines of different molar masses triangles 9400, and squares 44(X)gmol ) [145]...

Maeda, N., Rosenberg, K.J., Israelachvili, J.N., Pashley, R.M. Further studies on the effect of degassing on the dispersion and stability of surfactant-free emulsions. Langmuir 20, 3129-3137 (2004)... 

Kuehn, I. and Tauer, K. (1995) Nucle-ation in emulsion polymerization a new experimental study. 1. Surfactant-free emulsion polymerization of styrene. Macromolecuks, 28, 8122. 

Surfactant-free emulsion polymerkation are carried out in the absence of a surfactant [321], The technique requires the use of initiators that yields initiating species with surface-active properties and imparts them to the polymer particles. Examples of such initiators are persulfates. The lattices that form are stabilized by chemically bound sulfate groups that are derived from persulfate ions. Because the surface-active groups are chemically bound, the lattices are easier to purify and free the product from unreacted monomer and initiator. Generally, the particle number per milliliter from a surfactant-free emulsion polymerization is smaller than the particle number from typical emulsion polymerization. 

Describe a surfactant-free emulsion polymerization, and inverse emulsion polymerization and a miniemulsion polymerization. 

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