Persulfate as initiator

The ionic nature of the radicals generated, by whatever technique, can contribute to the stabilisation of latex particles. Soapless emulsion polymerisations can be carried out usiag potassium persulfate as initiator (62). It is often important to control pH with buffets dutiag soapless emulsion p olymerisation. 

Grafting and networking may modify the mechanical, chemical, and functional properties of polymers and enhance their utilization for some purposes, such as for water treatment (Kumar and Verma, 2007 Mishra et al., 2003). Psyllium derivatives were prepared by grafting acrylonitrile onto psyllium molecules using a ceric ammonium nitrate and nitric acid system (Mishra et al., 2003). The resulted grafted psyllium samples were not soluble in commonly used solvents or their combinations. In 2007, methacrylic acid derivatives of psyllium were prepared using ammonium persulfate as initiator and cross-linked using N,N-methylenebisacryla-mide as the crosslinker (Kumar and Verma, 2007). The modified psyllium... 

In this study, mechanical properties of emulsion copolymers of viityl acetate and butyl aciylate, which consisted of a nonionic emulsifier (30 mol ethoxylated nottyl-phenol), an oligomeric stabilizator, and ammonium persulfate or potassium persulfate as initiators by changing monomer ratios from 90 10 to 10 90 for VAc BuA, were determined by differential scanning calorimeter. 

Very recently, Ghosh and Mandal have reported (20) a thorough kinetic investigation of the polymerization of styrene in the two phase system water/o-dichiorobenzene using potassium persulfate as initiator and tetrabutylammoniurn bromide These studies were conducted at and pH, and found that the rate showed a square root dependence... 

Characterization of the polymer indicates that an application of sodium dodecyl sulfonate as anionic surfactant and sodium persulfate as initiator for both stages leads to a hemisphere particle... 

Imaz et al. [56] reported surfactant-free synthesis of PVCL microgels in aqueous phase in the presence of persulfate as initiator. The authors reported that the microgel particles possessed a size of 350 nm in swollen state below VPTT. 

In the polymerization of styrene, using potassium persulfate as initiator. Roe ( ) observed that the total number of particles in latices depended on the composition of the mixed surfactants and not on the total number of micelles. Therefore, he devaluated the micellar nucleation mechanism for emulsion polymerization as proposed by Harkins( ) -Smith-Ewart(j). 

The purpose of this paper is first to clarify the detailed characteristics of the emulsion polymerization of vinyl acetate using sodium laiiryl sulfate as emulsifier and potassium persulfate as initiator, and second to propose a new reaction model, based on our theory relating to the role of polymer particles, which enedsle vis to predict the number of polymer pcurticles produced and consequently, the progress of vinyl acetate emulsion polymerization. 

The usual combination of components in the polymerisation mixture, and the only one for which we shall give experimental details comprises buffer salts acrylamide monomer, methylene N,N -bisacryl-amide (Bis), tetramethyl ethylenediamine (TEMED) as catalyst and ammonium persulfate as initiator. Variants are possible as mentioned in the previous chapter other catalysts may be used and also there may in some cases be advantages in eschewing the use of the persulfate, for example, when it is important to avoid too rapid setting of the gel in the course of more than usually complex... 

For the emulsion polymerization of vinyl acetate without seed polymer imder purified nitrogen, using sodium laiuyl sulfate as surfactant and potassium persulfate as initiator, at 50°C, with agitation at 400 rpm in a resin kettle of 500 ml capacity, the same research group made the following observations [143]. 

Batch miniemulsion polymerizations aiVAc/BA were investigated using SO/50 and 25/75 molar ratios of the two monomers, SHS/HD as the surfactant/ cosurfactant system and anunonium persulfate as initiator [6]. The polymeriza-ticxis were conducted at 60°C with 25% solids fiamulations. The miniemulsion droplets were created using ultrasonificatioiL The polymerizations were c iarac-terized their reaction kinetics, copolyma compositions and propoties. and final particle size distributions. Parallel conventional emulsion polymmzations (i.e. no cosurlactant, no high shear) were conducted for comparison. 

Polystyrene beads (PS) are employed as physical templates for macropore. The emulsifier-fiee emulsion polymerization mediod used here allows for the synthesise of nearly monodisperse latex beads of PS in the size of ca 100 nm [10], PS beads were prepared using 700 ml degassed water, 54 ml styrene monomer, 0.65 g potassium persulfate as initiator, and 20 ml divinylbenzene as cross-linking agent. PS beads were obtained at 70°C and 350 rpm, and dried under ambient condition. Aluminum fec-butoxide and stearic acid were separately dissolved in patent alcohol, sec-butyl alcohol, at room tempature, and then the two solutions were mixed. Appropriate amount of HNO3 solution was dropped into the mixture at a rate of 1 ml/min to acidify and hydrolyze the aluminum precursor. PS beads were added into aluminum hydroxide solution after stirring for 10 h. The final pH of the reactant was approximately 7. Organic templates, both stearic acid and PS bead, were easily removed from dried aluminum hyc xide by calcination. The overall synthetic procedure is as shown in Fig. 1. 

The polymerization is guided as a radical polymerization using dibenzoylperoxide, 2,2 -azobisisobutyronitrile or ammonium persulfate as initiator. The backbone can be modified by the reaction of 4-vinylpyTidine with benzyl chloride to get N-benzyl-4-vinylpyrid-ine monomers (41). 

Poly(butyl methacrylate) latex nanoparticles have been synthesized by emulsion polymerization sodium dodecyl sulfate as a surfactant and potassium persulfate as initiator. Nanoparticles of various sizes could be synthesized in separate runs, with sizes of 100-300 nm. 

The emulsion polymerization reaction was accompHshed in conventional manner using potassium persulfate as initiator and sodium dodecyl sulfate as surfactant Stable composite latexes with diameters in the range of 50 to 150 nm were successfully produced, provided that the original clay suspension was stable enough. 

Consider that a 10,000 L semibatch reactor must process vinyl acetate monomer with ammonium persulfate as initiator and sodium lauryl sulfate as a stabilizing agent, with the problem statement given in subsection 3,2 and the following values ... 

A more recent development is template polymerization [520 522]. When acrylic acid was polymerized in aqueous solution using potassium persulfate as initiator, the polymerization proceeded very slowly. In the presence of poly(vinylpyrrolidone) but under otherwise identical reaction conditions, the rate of polymerization increased dramatically, depending on the amount of PVP. At nearly equimolar concentrations of PVP and monomer, the rate of polymerization reaches a maximum value, because of the strong interaction between poly(vinylpyrrolidone) and acrylic acid in aqueous solution (Scheme 40) [523]. 

It is well-established that emulsion polymerization systems which contain carboxylic-acid monomers polymerize more rapidly than do similar reaction systems which do not contain acid. The results shown in Pig.1 show the effect of increasing levels of methacrylic acid upon the conversion-time curve for the surfactant-free emulsion copolymerization of styrene with small amounts of methacrylic acid using potassium persulfate as initiator. The ability of a given molar amount of a carboxylic-acid monomer to enhance the rate of polymerization increases as the acid becomes... 

Recently, a novel graft copolymer of hydrophobically modified inulin (INUTEC S PI) has been used in emulsion polymerization of styrene, methyl methacrylate, butyl acrylate and several other monomers. All lattices were prepared by emulsion polymerization using potassium persulfate as initiator. The z-average particle size was determined by photon correlation spectroscopy (PCS) and electron micrographs were also taken. 

Manickham, et al. [11] reported similar orders with respect to monomer and initiator for polymerization in aqueous solution with persulfate as initiator. They also determined that the rate of polymerization increased with an increase in ionic strength of the reaction medium. 

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