Disperse Synthesis

Nasrullah MJ, Bahr JA, G lagher-Lein C, Webster DC, Roesler RR, Schmitt P (2009) Automated parallel polyurethane dispersion synthesis and characterization J Coatings Tech Res 6 1-10... 

Caviion. The same precautions outlined in the preparation of sodium dispersions (synthesis 2) must be observed. 

Dispersions of sodium hydride in oil are white or light gray and have roughly the same viscosity characteristics as sodium dispersions (synthesis 2). Such dispersions are useful as safe and convenient means of adding sodium hydride in such reactions as Claisen or Stobbe condensations, in preparations of complex hydrides, and in reductions of metal salts. 

Method of Hybrid Dispersion Synthesis and Kind of Initiating System... 

The results of investigations of the effect of method of hybrid dispersion synthesis (la, lb, 2 or 3 - see Section 3.2) on the properties of dispersions as well as of films and coatings made from them are presented in Tables 6.9 to 6.11 (dispersions prepared using water-soluble initiator) and in Tables 6.12 to 6.14 (dispersions prepared using redox initiating system). In all dispersions the chemical structure of the polyurethane-urea and acrylic/styrene polymer component was the same (see relevant tables in Section 6.5.2). All the dispersions contained a similar low level (2-3.6%) of NMP. 

The chemical structure of the acrylic/styrene part of the hybrid has a substantial effect on the properties of films made from hybrid dispersions (see Table 6.24). When the monomers that form polymers of high Tg (styrene or MM) are used and the synthesis is carried out according to method la, no film is obtained. For the same monomers but a different method of dispersion synthesis (method 3), a film was obtained only for styrene and only when a high level of coalescent was applied. In this case, the mechanical properties, water and solvent resistance of the film were quite good, but the film was not transparent, which... 

Lu Y, Larock RC. Soybean oil-based, aqueous cationic polyurethane dispersions synthesis and properties. Prog Org Coat 2010 69(l) 31-7. 

Manna A et al 1997 Synthesis and oharaoterization of hydrophobio, approtioally-dispersible silver nanopartioles in Winsor Type II mioroemulsions Chem. Mater. 9 3032... 

The derivatives are hydroxyethyl and hydroxypropyl cellulose. AH four derivatives find numerous appHcations and there are other reactants that can be added to ceUulose, including the mixed addition of reactants lea ding to adducts of commercial significance. In the commercial production of mixed ethers there are economic factors to consider that include the efficiency of adduct additions (ca 40%), waste product disposal, and the method of product recovery and drying on a commercial scale. The products produced by equation 2 require heat and produce NaCl, a corrosive by-product, with each mole of adduct added. These products are produced by a paste process and require corrosion-resistant production units. The oxirane additions (eq. 3) are exothermic, and with the explosive nature of the oxiranes, require a dispersion diluent in their synthesis (see Cellulose ethers). 

Another compound of interest is adenine [73-24-5] or 6-aminopurine (53) derived from pheny1a 2oma1ononitri1e (92). The introduction of the dicyanostyryl moiety has led to the industriali2ation of several methine dyes such as the Cl Disperse Yellow [6684-20-4] (54) (93). The Cl Disperse Blue 354 [74239-96-6] (55) also represents a new class of anTinoarylneutrocyariine dyes with a brilliant blue shade (94). The dimer of malononitrile is also used for the synthesis of new dyes (95). 

These smaU molecules are ideal for penetrating dense fibers such as polyester, and are therefore used as disperse dyes for polyester. AU the important dyes are yeUow in (75) X = H is Cl Disperse YeUow 14 [961-68-2], X = OH is Cl Disperse YeUow 1 [119-15-3], and X = NH2 is Cl Disperse YeUow 9 [6373-73-5]. Although the dyes are not terribly strong (e ax 20,000), they are cost-effective because of their easy synthesis from inexpensive intermediates. Cl Disperse YeUow 42 [5124-25-4] and Cl Disperse YeUow 86 are important lightfast dyes for automotive-grade polyester. 

The synthesis of an anthraquinone dye generally involves a large number of steps. For example. Cl Disperse Red 60 [17418-58-5] (10) (Cl 60756) (a typical disperse red dye) requites five steps starting from anthraquinone, and Cl Disperse Blue 56 [31810-89-6] (11) (Cl 63285) requites six steps. 

Azetidine, 7V-bromo-, 7, 240 Azetidine, AT-r-butyl- N NMR, 7, 11 Azetidine, AT-t-butyl-3-chloro-transannular nucleophilic attack, 7, 25 Azetidine, 3-chloro-isomerization, 7, 42 Azetidine, AT-chloro-, 7, 240 dehydrohalogenation, 7, 275 Azetidine, 7V-chloro-2-methyl-inversion, 7, 7 Azetidine, 3-halo-synthesis, 7, 246 Azetidine, AT-halo-synthesis, 7, 246 Azetidine, AT-hydroxy-synthesis, 7, 271 Azetidine, 2-imino-stability, 7, 256 Azetidine, 2-methoxy-synthesis, 7, 246 Azetidine, 2-methyl-circular dichroism, 7, 239 optical rotatory dispersion, 7, 239 Azetidine, AT-nitroso-deoxygenation, 7, 241 oxidation, 7, 240 synthesis, 7, 246 Azetidine, thioacyl-ring expansion, 7, 241 Azetidine-4-carboxylic acid, 2-oxo-oxidative decarboxylation, 7, 251 Azetidine-2-carboxylic acids absolute configuration, 7, 239 azetidin-2-ones from, 7, 263 synthesis, 7, 246... 

Hazardous chemicals or mixtures may be replaceable by safer materials. These may be less toxic per se, or less easily dispersed (e.g. less volatile or dusty). Substitution is also applicable to synthesis routes to avoid the use of toxic reactants/solvents or the production, either intentionally or accidentally, of toxic intermediates, by-products or wastes. 

The waterborne prepolymer process is similar to the prepolymer synthesis described earlier, except that most of the waterborne prepolymers are based on aliphatic isocyanates and contain an internal emulsifier. There are several types of internal emulsifiers, both anionic and cationic. A good summary of these stabilizers is found elsewhere [56], The majority of the waterborne urethanes are anionic dispersions. An internal surfactant, such as dimethylolpropionic acid, is often incorporated into the prepolymer ... 

The chain extension step may then take place in the water phase. Hydrazine and ethylene diamine are commonly used chain extenders for waterborne urethane dispersions. The isocyanates react with the diamine chain extenders much faster than with the water, thus forming polyurea linkages and building a high molecular weight polymer. More detailed information regarding the synthesis and process of making waterborne polyurethane dispersions is found in Dieterich s review article [58]. 

Beaded acrylamide resins (28) are generally produced by w/o inverse-suspension polymerization. This involves the dispersion of an aqueous solution of the monomer and an initiator (e.g., ammonium peroxodisulfates) with a droplet stabilizer such as carboxymethylcellulose or cellulose acetate butyrate in an immiscible liquid (the oil phase), such as 1,2-dichloroethane, toluene, or a liquid paraffin. A polymerization catalyst, usually tetramethylethylenediamine, may also be added to the monomer mixture. The polymerization of beaded acrylamide resin is carried out at relatively low temperatures (20-50°C), and the polymerization is complete within a relatively short period (1-5 hr). The polymerization of most acrylamides proceeds at a substantially faster rate than that of styrene in o/w suspension polymerization. The problem with droplet coagulation during the synthesis of beaded polyacrylamide by w/o suspension polymerization is usually less critical than that with a styrene-based resin. 

In this chapter, the polymerization methods used for the production of uniform latex particles in the size range of O.I-lOO /Ltm are described. Emulsion, swollen emulsion, and dispersion polymerization techniques and their modified forms for producing plain, functionalized, or porous uniform latex particles are reviewed. The general mechanisms and the kinetics of the polymerization methods, the developed synthesis procedures, the effect of process variables, and the product properties are discussed. 

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