Persulphate as Initiator

A novel graft copolymer of hydrophobically modified inuhn (INUTEC SPl) has been used in the emulsion polymerisation of styrene, MMA, butyl acrylate, and several other monomers [8]. All lattices were prepared by emulsion polymerisation, using potassium persulphate as initiator, and the z-average particle size was determined using PCS electron micrographs were also recorded. 

SiUcone-modified styrene-butyl acrylate copolymer latex was synthesised by emulsion copolymerisation using octamethylcyclotetrasiloxane(D4), styrene and butyl acrylate as raw materials, potassium persulphate as initiator and propylmethacrylate triethoxysilane as crosslinking agent. The IR spectroscopic studies showed that the vinyl monomers were completely copolymerised with D4. The prepared silicone-modified copolymer latex with the IPNs tended to have higher stability and better toluene and water resistance than styrene-butyl acrylate copolymer latex. The glossiness of coated paper was improved with silicone-modified copolymer latex and it was at a maximum when D4 was about 3% of total monomers. 16 refs. 

Copolymer latices of styrene and acrylates (mainly butyl acrylate) were synthesised. Sodium dodecyl sulphate and ethoxylated nonyl phenol containing ten ethylene oxide units were used as surfactants and potassium persulphate as initiator. A coating for paper was made on the basis of the copolymer latices and white pigments. The performance of the coated paper was measured. By varying experimental conditions such as comonomer proportion and amounts of emulsifiers and of initiator, a copolymer latex suitable for paper coating was prepared. Paper coated with latex showed satisfactory properties in... 

Heterogeneous latices were prepared by a two-stage seeded emulsion polymerisation process at 80C using potassium persulphate as initiator and sodium dodecyl sulphate as emulsifier. Styrene-methacrylic acid (MAA) copolymer latices containing varying amounts of MAA were used as seeds. The second stage polymerisation was performed either as a seeded batch process or as a seeded... 

Psyllium gum and methacrylamide polymeric complex using N,N-methylene-bisacrylamide as crosslinker and ammonium persulphate as initiator Tetracycline HCl hydrogel The release profile of tetracycline from psy-cl-poly (MAAm) polymeric matrix followed Fickian type diffusion mechanism. [159]... 

Commercial polymerizations are typically carried out in jacketed glass-lined kettles at about 40 C using potassium persulphate as initiator with the emulsifier being formed in situ using rosin, aqueous caustic soda and the sodium salt of a naphthalene sulphonic acid-formaldehyde condensation product. Monomer conversion is followed by measuring the specific gravity of the emulsion. In the case of sulphur-modified polychloroprenes polymerization may be... 

The liquids used in glass-ionomer cements are acidic polyelectrolytes and are homo- or copolymers of acrylic acid in concentrated aqueous solutions (6,7). These polyacids are generally prepared by the aqueous polymerization of the unsaturated carboxylic acids using ammonium persulphate as initiator and isopropyl alcohol as the chain transfer agent. Tartaric acid is generally added to the liquids to sharpen the setting of their cement (8). Examples of the liquids used in ionomer cement formulations are given in Table 1. 

The most common poly(alkenoic acid) used in polyalkenoate, ionomer or polycarboxylate cements is poly(acrylic acid), PAA. In addition, copolymers of acrylic acid with other alkenoic acids - maleic and itaconic and 3-butene 1,2,3-tricarboxylic acid - may be employed (Crisp Wilson, 1974c, 1977 Crisp et al, 1980). These polyacids are prepared by free-radical polymerization in aqueous solution using ammonium persulphate as the initiator and propan-2-ol (isopropyl alcohol) as the chain transfer agent (Smith, 1969). The concentration of poly(alkenoic add) is kept below 25 % to avoid the danger of explosion. After polymerization the solution is concentrated to 40-50 % for use. 

The monomers get absorbed in micelles resulting in their swelling. Water soluble initiators are used which form free radicals. Inorganic persulphates are commonly used as initiators. The initiator diffuses into a micelle and polymerisation proceeds. As more monomer is polymerised monomers from outside the micelle diffuse inside and the process continues when another radical enters the micelle the polymerisation stops. This technique can give high Molecular weight polymers. 

Polymerization of the gel may be achieved either by ultraviolet photoactivation with riboflavin, or, preferably, using ammonium persulphate as a catalyst. It is necessary to include an initiator for the reaction, TEMED (tetramethylethylene diamine) being commonly used. 

As published by Ferguson and Shah and independently by Bamford and Shiiki, polyethylene imine can be used as template for polymerization of acrylic acid. It was found that polyethylene imine forms water insoluble complex with polyacrylic acid. Polymerization was carried out at 31 C, using potassium persulphate as an initiator. The polymerization was followed by turbimetry and bromometric titration. During polymerization, the precipitation takes place, however, at GO C, degradation of the com-... 

An elegant example of the analysis of colloid surfaces containing covalently attached hydrophilic species has been provided by Brindley et al who studied the surface chemistry of polystyrene colloids with surface grafted polyethylene glycol groups [39]. These colloids were prepared by surfactant-free copolymerization of styrene with PEG using potassium persulphate as an initiator. The XPS analysis of these microparticles is shown in Fig. 11. 

Water-soluble initiators used in emulsion polymerization are preferentially sodium, potassium or ammonium persulphate operating at 50-80°C. Redox systems use hydrogen peroxide or a persulphate as the oxidizing moiety and sodium metabisulphite, sodium hydrosulphate (also known as hyposulphite or dithionite), sodium thiosulphate and sodium formaldehyde sulphoxylate as the reductant. 

Polyacrylamide gels are prepared by copolymerisation of acrylamide monomer (CH2=CHCO NH2) with a cross linking agent, usually N, N-methylene bisacrylamide, CH2(NHCOCH = CH2)2, in the presence of a catalyst accelerator-chain initiator mixture. This mixture may consist of freshly prepared ammonium persulphate as catalyst (0.1 to 0.3% w/v) together with about the same concentration of a suitable base, for example, dimethylamino propionitrile (DMAP) or N, N, N, N tetramethylene diamine (TEMED) as initiator. TEMED is most frequently used and proportional increases in its concentration speed up the rate of gel polymerisation. Photochemical polymerisation may be brought about by riboflavin in the presence of UV radiation. Gelation is due to vinyl polymerisation as shown below ... 

Those cores have been eopolymerized under miniemulsion conditions using sodium dodecyl sulphate (SDS) as surfactant and potassium persulphate (KPS) as initiator with styrene as matrix monomer... 

Nanosized PS latexes with high polymer contents were obtained by the copolymerisation of styrene with an ionic comonomer (sodium styrenesulphonate), a non-ionic comonomer (2-hydroxyethyl methacrylate), or both in the absence of an emulsifier and with potassium persulphate as an initiator at 70C. The maximum polymer content was up to 25 wt% with only 0.6 wt% of sodium styrenesulphonate or 2-hydroxyethyl methacrylate. The controlled addition of monomer(s) to the primary particles formed in an emulsion yielded smaller latex particles of a rather uniform size. The results showed that the surface of the latex particles was enriched in the comonomers. 25 refs. 

The above latices were prepared by batch precipitation polymerisation of N-isopropylmethacrylamide using methylenebisacrylamide, as crosslinker, and potassium persulphate, as polymerisation initiator. The effect of the crosslinker on total conversion of polymer, latex particle size and morphological properties and colloidal properties of the final microgel particles were investigated. The relationship between the amount of water-soluble polymer and amount of crosslinker and the influence of temperature on the electrophoretic mobility of the latex are considered. 11 refs. 

The encapsulation of seed polymer particles coated by anionic iron oxide nanoparticles is investigated using N-isopropylacrylamide as a main monomer, N,N-methylene bisacrylamide as a crosslinking agent, itaconic acid as a functional monomer and potassium persulphate as an anionic initiator. The magnetic latexes obtained are... 

Persulphates (inorganic diperoxysulphates of ammonium, potassium, and sodium, and triple salt potassium monopersulphate) are used as initiators in the polymer and fibre industry, as well as other applications in other industrial sectors. 

Details of the processes used to produce vinylidene fluoride-hexafluoropropylene copolymers have not been disclosed but the copolymers may be prepared by emulsion polymerization under pressure using a persulphate-bisulphite initiator system. Highly fluorinated surfactants, such as ammonium perfluorooctoate, are most commonly used in order to avoid chain transfer reactions. The preferred vinylidene fluoride content for commercial copolymers is about 70% mole. The structure of such a copolymer might be represented as follows ... 

When redox compounds are used, either as initiators or as a means of reducing remaining monomer, the natural tendency is for a small amount of residual reducing agent to be present. It was eventually realised that to prevent the destabilisation of BIT such a net reducing state needs to be present in protected products. In dispersions where the residual redox agent was an oxidiser, especially persulphate, rapid and, on several occasions, catastrophic degradation of BIT occurred. 

In the process of emulsion polymerization as initiating system one uses often a mixture of potassium persulphate and sodium thiosulfate ... 

Such reactions can be initiated by free radicals, derived from compounds (initiators) such as benzoyl peroxide, ammonium persulphate or azobis-isobutyronitrile or by ionic mechanisms... 

Since poly(vinyl acetate) is usually used in an emulsion form, the emulsion polymerisation process is commonly used. In a typical system, approximately equal quantities of vinyl acetate and water are stirred together in the presence of a suitable colloid-emulsifier system, such as poly(vinyl alcohol) and sodium lauryl sulphate, and a water-soluble initiator such as potassium persulphate. 

To produce the Type 2 polymers, styrene and acrylonitrile are added to polybutadiene latex and the mixture warmed to about 50°C to allow absorption of the monomers. A water-soluble initiator such as potassium persulphate is then added to polymerise the styrene and acrylonitrile. The resultant materials will be a mixture of polybutadiene, polybutadiene grafted with acrylonitrile and styrene, and styrene-acrylonitrile copolymer. The presence of graft polymer is essential since straightforwsird mixtures of polybutadiene and styrene-acrylonitrile copolymers are weak. In addition to emulsion processes such as those described above, mass and mass/suspension processes are also of importance. 

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