Potassium persulfate polymerization

O Polymerization initiated by potassium persulfate Polymerization initiated by cumene hydroperoxide A Calculated from (55)... 

Polymerization takes place, in the following manner in the presence of suitable peroxide catalyst these compounds polymerize with themselves (homopolymerizatiOn) in aqueous emulsion. When the reaction is complete, the emulsified polymer may be used directly or the emulsion coagulated to yield the solid polymer (312). A typical polymerization mixture is total monomer (2-vinylthiazole), 100 sodium stearate, 5 potassium persulfate, 0.3 laurylmercaptan, 0.4 to 0.7 and water, 200 parts. 

The most common water-soluble initiators are ammonium persulfate, potassium persulfate, and hydrogen peroxide. These can be made to decompose by high temperature or through redox reactions. The latter method offers versatility in choosing the temperature of polymerization with —50 to 70°C possible. A typical redox system combines a persulfate with ferrous ion ... 

Propagation. The rate of emulsion polymerization has been found to depend on initiator, monomer, and emulsifier concentrations. In a system of vinyl acetate, sodium lauryl sulfate, and potassium persulfate, the following relationship for the rate of polymerization has been suggested (85) ... 

Free-Radical Polymerization. The best method for polymerising isoprene by a free-radical process is emulsion polymerisation. Using potassium persulfate [7727-21-1] as initiator at 50°C, a 75% conversion to polyisoprene in 15 h was obtained (76). A typical emulsion polymerisation recipe is given as follows (77). 

Water-soluble free radical initiators (i.e., potassium persulfate, K2S2O8) are used in the emulsion polymerization process. Upon heating, the persulfate ion decomposes into two sulfate ion free radicals according to the following reaction ... 

The polymerization reaction is conducted at the desired temperature with a slow stirring regime for a certain period. A typical recipe for the emulsion polymerization of styrene is exemplified in Table 1 [40]. As seen here, potassium persulfate and sodium dodecyl sulfate were used as the initiator and the stabilizer, respectively. This recipe provides uniform polystyrene particles 0.22 /Lim in size. 

Normally, persulfate (41) can only be used to initiate polymerization in aqueous or part aqueous (emulsion) media because it has poor solubility in most organic solvents and monomers. However, it has been reported that polymerizations in organic solvent may be initiated by crown ether complexes of potassium persulfate.234 237 Quaternary ammonium persulfates can also serve as useful initiators in organic media. 4 The rates of decomposition of both the crown ether complexes and the quaternary ammonium salts appear dramatically... 

Vinyl monomers may be polymerized at favorable rates in an aqueous medium containing an emulsifier and a water-soluble initiator. A typical simple Tecipe would consist of the following ingredients with their proportions indicated in parts by weight 100 of monomer, 180 of water, 2 to 5 of a fatty acid soap, and 0.1 to 0.5 of potassium persulfate. Cationic soaps (e.g., dodecylamine hydrochloride) may be used instead of the fatty acid soap, and various other initiators may replace the persulfate (e.g., hydrogen peroxide and ferrous ion, or a water-soluble organic hydroperoxide). 

Radical polymerization of styrene was carried out in the presence of bare silica particles, and of the HPC-coated silica particles in water by using potassium persulfate as an initiator. Table 2 gives the typical ingredients used for these polymerizations. The HPC-coated silica particles were prepared under the same conditions as in the adsorption experiments. The polymerization temperature was kept at 1+5 °C to protect the adsorption layer of HPC, and polymerized for 2l+ hrs in the same manner as that... 

DVB (purity > 98 %) was polymerized using sodium dodecyl sulfate (SDS) as emulsifier in the presence of various initiators, such as potassium persulfate (PPS) [51,77-82], 2,2 -azobisisobutyronitrile (AIBN) [83] and also by thermal initiation [84]. 

Rasmussen and co-workers. Chapter 10, have shown that many free-radical polymerizations can be conducted in two-phase systems using potassium persulfate and either crown ethers or quaternary ammonium salts as initiators. When transferred to the organic phase persulfate performs far more efficiently as an initiator than conventional materials such as azobisisobutyronitrile or benzoyl peroxide. In vinyl polymerizations using PTC-persulfate initiation one can exercise precise control over reaction rates, even at low temperatures. Mechanistic aspects of these complicated systems have been worked out for this highly useful and economical method of initiation of free-radical polymerizations. 

A critical survey of the literature on free radical polymerizations in the presence of phase transfer agents indicates that the majority of these reactions are initiated by transfer of an active species (monomer or initiator) from one phase to another, although the exact details of this phase transfer may be influenced by the nature of the phase transfer catalyst and reaction medium. Initial kinetic studies of the solution polymerization of methyl methacrylate utilizing solid potassium persulfate and Aliquat 336 yield the experimental rate law ... 

In 1981 we reported (2, 3) the first examples of free radical polymerizations under phase transfer conditions. Utilizing potassium persulfate and a phase transfer catalyst (e.g. a crown ether or quaternary ammonium salt), we found the solution polymerization of acrylic monomers to be much more facile than when common organic-soluble initiators were used. Somewhat earlier, Voronkov and coworkers had reported (4) that the 1 2 potassium persulfate/18-crown-6 complex could be used to polymerize styrene and methyl methacrylate in methanol. These relatively inefficient polymerizations were apparently conducted under homogeneous conditions, although exact details were somewhat unclear. We subsequently described (5) the... 

Takeishi, et. al, have described the redox polymerization of methyl methacrylate in the absence of solvent (6). With 18-crown-6 as the phase transfer catalyst and potassium persulfate/sodiurn bisulfite as the redox couple, polymerization was observed at temperatures <50 C whereas little or no polymerization occurred under these conditions in the absence of bisulfite. Above 55 C, however, polymerization occurred even in the absence of bisulfite. From the limited kinetic data reported (6), one can estimate (13) that the rate of polymerization (Rp) is approximately proportional to the square root of crown concentration (Equation 1) ... 

In our initial studies of the polymerization of butyl acrylate by solid potassium persulfate in acetone solution (2), we attempted to relate the rate of polymerization to the ability of various crown ethers to complex the potassium cation. A reasonable correlation was discovered between log Rp and log K, where K represents the binding constant of the crown ether for in methanol solution (Figure 1). This finding provided some support for the idea that a typical phase transfer process was occurring in these reacti ons. 

Polymerization of butyl acrylate was also studied by us in ethyl acetate/water two phase systems (3) using potassium persulfate/quaternary ammonium salts as the initiator system. Under these conditions (a minimum amount of water was used to dissolve the persulfate), it was found that symmetrical quat salts were more efficient than surfactant type quat salts. Also, the more lipophilic quat salts were more efficient. These results prompted us to propose formation of an organic-soluble quaternary ammonium persulfate via typical phase transfer processes. 

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... 

Our kinetic studies have concentrated on the polymerization of MMA in organic solution using solid potassium persulfate and a phase transfer catalyst. 

Case 1 appears to accurately predict the observed dependence on persulfate concentration. Furthermore, as [Q]+otal approaches [KX], the polymerization rate tends to become independent of quat salt concentration, thus qualitatively explaining the relative insensitivity to [Aliquat 336]. The major problem lies in explaining the observed dependency on [MMA]. There are a number of circumstances in free radical polymerizations under which the order in monomer concentration becomes >1 (18). This may occur, for example, if the rate of initiation is dependent upon monomer concentration. A particular case of this type occurs when the initiator efficiency varies directly with [M], leading to Rp a [M]. Such a situation may exist under our polymerization conditions. In earlier studies on the decomposition of aqueous solutions of potassium persulfate in the presence of 18-crown-6 we showed (19) that the crown entered into redox reactions with persulfate (Scheme 3). Crematy (16) has postulated similar reactions with quat salts. Competition between MMA and the quat salt thus could influence the initiation rate. In addition, increases in solution polarity with increasing [MMA] are expected to exert some, although perhaps minor, effect on Rp. Further studies are obviously necessary to fully understand these polymerization systems. 

The synthetic methods and chemical characterization data for the various polymeric materials to be discussed in this work have been reported elsewhere [6-8]. In some cases copolymerization of the unchlorinated oxazolidinone monomer with other common monomers such as acrylonitrile, vinyl chloride, styrene, and vinyl acetate, using potassium persulfate as an initiator, was performed. In other cases the unchlorinated oxazolidinone monomer was grafted onto polymers such as poly(acrylonitrile), poly(vinyl chloride), poly(styrene), poly(vinyl acetate), and poly(vinyl alcohol), again using potassium persulfate as an initiator. 

The unsulfonated random copolymers are reportedly synthesized at 50 °C over a period of 48 h using emulsion polymerization with dodecylamine hydrochloride surfactant in water as the reaction system and potassium persulfate as the initiator. The copolymer is then dissolved in an appropriate solvent such as dichloroethane or chloroform and sulfonated using reagents such as chlorosulfonic acid or a sulfur trioxide complex. It has been reported that this generation of BAM membranes exhibited some su-... 

Materials. The polystyrene latex, with a mean diameter of 0.42 fim, was synthesized by emulsifier-free emulsion polymerization. Potassium persulfate was used as initiator and the surface charge that stabilizes the latex particles thus originates from sulfate radicals. The synthesis was carried out at the Department of Polymer Technology at Abo Akademi, Finland. 

The thermal initiator system. This system is made up of water-soluble materials that produce free radicals at a certain temperature to initiate polymerization. The most commonly used i materials for such thermal emulsion polymerizations are potassium persulfate, sodium persulfate, or ammonium persulfate. 

The need for increased stabilities and for controllable permeabilities and morphologies led to the development of polymerized surfactant vesicles [55, 158-161]. Vesicle-forming surfactants haw been functionalized by vinyl, methacrylate, diacetylene, isocyano, and styrene groups in their hydrocarbon chains or headgroups. Accordingly, SUVs could be polymerized in their bilayers or across their headgroups. In the latter case, either the outer or both the outer and inner surfaces could be polymerized separately (Fig. 38). Photopolymerization links both surfaces selective polymerization of the external SUV surface is accomplished by the addition of a water-soluble initiator (potassium persulfate, for example) to the vesicle solution. 

Polymerization. Poly (methyl methacrylate) was obtained commercially. The polymers of other methacrylates and their copolymers were prepared in toluene with 2,2 -azobisisobutyronitrile (AIBN) at 60 °C. All the polymers prepared free radically were syndiotactic or atactic. Isotactic poly(a,a-dimethylbenzyl methacrylate) was obtained using C6H5MgBr as the initiator in toluene at 0°C. Poly(methacrylic acid) was prepared in water using potassium persulfate at as the initiator 60 °C. The molecular weights, glass transition temperatures and tacticities of the polymethacrylates are summarized in Table I. 

On the other hand, chemicals might be chosen as agents for generation of active centers in the polymeric backbone and grafting of monomer in the vapor phase. Ammonium persulfate and styrene (189), acrylic acid (190), butyl acrylate (191), potassium persulfate and n-butyl maleate or 2-ethyl hexyl acrylate (55,134) and ammonium ceric nitrate and methacrylic add (192) are examples of this method. Benzoyl peroxide deposited on polycaprolactam fibers initiates the grafting of styrene in vapor phase (193). 

Formulas for emulsion polymerization also include buffers, free radical initiators, such as potassium persulfate (KiSiOs), chain transfer agents, such as dodecyl mercaptan (G sSTT). The system is agitated continuously at temperatures below 100°C until polymerization is essentially complete or is terminated by the addition of compounds such as dimethyl dithiocarbamate to prevent the formation of undesirable products such as cross-linked polymers. Stabilizers such as phenyl Beta-naphthylamine are added to latices of elastomers. 

Emulsions may be polymerized by use of a water-soluble catalyst (initiator), such as potassium persulfate, or a monomer-soluble catalyst, such as benzoyl peroxide, lauroyl peroxide or azobisisobutyronitrilc. Suspension and solution polymerizations employ the monomer soluble catalysts only. In addition to the above-mentioned initiators, diisopropyl pcroxydi-carbonatc may also be employed, where lower-temperature polymerization may be desired, e.g., to reduce branching and minimize degradation. 

Grafting by chain transfer initiation has been carried out not only in homogenous medium but also by emulsion polymerization techniques, where the monomer and the catalyst are added to a latex containing the original backbone polymer (99). The efficiency of grafting increases with an increase of temperature of polymerization and with an increase of initiator concentration (generally potassium persulfate) these results indicate not only that the chain transfer reaction has a higher activation... 

The first report of the polymerization of tetrafluoroethylene was by Plunkett in 1941, who had a cylinder of tetrafluoroethylene cut open to see why the expected amount of gas was not released when the valve was opened. His perspicacity led to the discovery of an inert, white, opaque solid with a waxy feel. Various methods of polymerization were tried after the adventitious discovery and the preferred methods for polymerization now involve aqueous media and super-atmospheric pressures. Suitable initiators (Hanford and Joyce) include ammonium, sodium, or potassium persulfate, hydrogen peroxide, oxygen, and some organic peroxy compounds. Oxidation-reduction initiation systems involving the use of persulfate with either ferrous ion or bisulfite or the use of bisulfite with ferric ion are also useful and have been discussed by Berry and Peterson. 

In 1952 W. J. Priest, in an important paper, laid out all of the basic qualitative features of the theory of homogeneous nucleation in emulsion polymerization as it is known today (12). This was based upon his studies of particle size distributions in vinyl acetate polymerization initiated by potassium persulfate (K2S20g) in the presence of varying amounts of different stabilizers and inhibitors at several temperatures. Priest proposed that (1) "polymerization in solution is the initial process" ... 

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