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Polymerization methods chlorides

Interfdci l Composite Membra.nes, A method of making asymmetric membranes involving interfacial polymerization was developed in the 1960s. This technique was used to produce reverse osmosis membranes with dramatically improved salt rejections and water fluxes compared to those prepared by the Loeb-Sourirajan process (28). In the interfacial polymerization method, an aqueous solution of a reactive prepolymer, such as polyamine, is first deposited in the pores of a microporous support membrane, typically a polysulfone ultrafUtration membrane. The amine-loaded support is then immersed in a water-immiscible solvent solution containing a reactant, for example, a diacid chloride in hexane. The amine and acid chloride then react at the interface of the two solutions to form a densely cross-linked, extremely thin membrane layer. This preparation method is shown schematically in Figure 15. The first membrane made was based on polyethylenimine cross-linked with toluene-2,4-diisocyanate (28). The process was later refined at FilmTec Corporation (29,30) and at UOP (31) in the United States, and at Nitto (32) in Japan. [Pg.68]

Because almost any diacid can be leaddy converted to the acid chloride, this reaction is quite versatile and several variations have been developed. In the interfacial polymerization method the reaction occurs at the boundary of two phases one contains a solution of the acid chloride in a water-immiscible solvent and the other is a solution of the diamine in water with an inorganic base and a surfactant (48). In the solution method, only one phase is present, which contains a solution of the diamine and diacid chloride. An organic base is added as an acceptor for the hydrogen chloride produced in the reaction (49). Following any of these methods of preparation, the polymer is exposed to water and the acid chloride end is converted to a carboxyhc acid end. However, it is very difficult to remove all traces of chloride from the polymer, even with repeated washings with a strong base. [Pg.224]

As a variation on the base-catalyzed nucleopbilic displacement chemistry described, polysulfones and other polyarylethers have been prepared by cuprous chloride-catalyzed polycondensation of aromatic dihydroxy compounds with aromatic dibromo compounds. The advantage of this route is that it does not require that the aromatic dibromo compound be activated by an electron-withdrawing group such as the sulfone group. Details of this polymerization method, known as the Ullmaim synthesis, have been described (8). [Pg.462]

When the reactants involved in a step growth polymerization process are mutually immiscible, we can employ an interfacial polymerization method. Two solutions, each containing one of the monomers, are layered one on top of the other. This creates a phase boundary that forms wth the least dense liquid on top. The different monomers can then meet and polymerize at the interface. A commonly demonstrated example of this is the manufacture of nylon 610 by the interfacial reaction between an aqueous solution of hexamethylenediamine with sebacoyl chloride dissolved in carbon tetrachloride. Because the reaction only occurs at the interface, it is possible to pull the products from this interface to isolate the final product. [Pg.56]

The polymerization method used was a polyeondensation of tereph-thaloyl chloride, propane 1,2-diol, and the appropriate soft block (Figure 1) in a 20% solution in dry 1,2-dichloroethane at 85°C for 48 hours. [Pg.157]

A4 the higher temperatures used in melt polycondensations it is necessary to remove the liberated hydrogen chloride by bubbling inert gas through the reaction medium. Side reactions are common, and this polymerization method is used only rarely. No major kinetic studies have been made. [Pg.519]

With the present series of monomers, described in Table I, the polymerization methods studied were the same as those described in previous work (2). Again, polymerization of concentrated aqueous solutions of the amine hydrochlorides using the titaneous chloride/ hydrogen peroxide initiation system provided the best polymerization method. Where this technique did not yield polymers, other free-radical initiation systems were equally unsuccessful. Table II gives some examples of the results of these polymerization experiments. [Pg.214]

Four commercial methods are used to polymerize vinyl chloride. These are emulsion polymerization, suspension polymerization, bulk polymerization, and solution polymerization. The first two are the only techniques of significance with respect to fluid vinyl systems. [Pg.1207]

Polyanhydrides have been synthesized by the following methods a) bulk melt condensation of activated diadds, b) ring opening polymerization, c) reaction between dibasic acid and diacid chlorides, and d) interfacial polymerization. A detailed study of these polymerization methods and various polymerization conditions for a range of diadds were previously described [25-27],... [Pg.99]

All these developed living cationic polymerization methods for isobutene provide defined tertiary chloride end groups, opening up possibilities for further end-group functionalization. A representative example was reported by Ivan and Kennedy, who described the quantitative conversion of the chloride into allyl-terminated PIB, which was converted into epoxy and hydroxyl-functional PIBs [34]. [Pg.168]

Methods of polymerization of vinyl chloride currently in practice are suspension, emulsion, and bulk polymerization. The suspension polymerization is adopted in most cases. There is a low-temperature polymerization method to obtain crystalline PVC [149]. [Pg.315]

The familiar polymers polyvinyl chloride (PVC), polystyrene (PS), and polymethylmethacrylate (PMMA), which were produced in the 1930s and 1940s in large-scale production plants, are examples of so-called radical chain polymerization. One way of replacing the high-pressure polymerization method used for ethylene (ICI), which involved radical catalysts, with a low-pressure process, was provided by anionic coordinative catalysts, for example titanium tetrachloride plus aluminum triethyl as a cocatalyst in the method according to K. Ziegler (1953). [Pg.21]

Thus, optimization of all of the parameters in one experiment is difficult. In contrast, chemical polymerization does not require any special instruments it is a rather simple and fast process. Chemical polymerization method involves oxidative polymerization of pyrrole monomer by chemical oxidants either in aqueous or non-aqueous solvents or oxidation by chemical vapor deposition in order to produce bulk polypyrrole as fine powders. Fe(III) chloride and water are found to be the best oxidant and solvent for chemical polymerization of pyrrole respectively regarding desirable conductivity characteristics. [Pg.243]

Acrylamide monomer is a white crystal, available commercially as a 50 wt % aqueous solution. Acrylamide monomer can be polymerized to a very-high-molecular-weight (lO -lO g/mole) homopolymer, copolymer, or terpolymer. Polyacrylamide (PAM) is a nonionic polymer. The anionic polyacrylamide species can be obtained from the hydrolysis of the amide (—CONH ) functional group of the homopolymer, or from the copolymerization of acrylamide with an anionic monomer, such as acrylic acid (AA) or 2-acrylamino 2-methyl propane sulfonic acid (AMPS). Acrylamide can be copolymerized with a cationic monomer, such as dimethyl diallylammonium chloride (DMDAAC) or acryloyloxyethyl trimethyl ammonium chloride (AETAC), to form the cationic acrylamide polymer. Acrylamide can simultaneously react with anionic and cationic monomers to form a polyampholyte. The acrylamide homopolymer, copolymers, and terpolymers are synthesized (1-20) by free radicals via solution or emulsion or other polymerization methods. F. A. Adamsky and E. J. Beckman (21) reported the inverse emulsion polymerization of acrylamide in supercritical carbon dioxide. The product classes of acrylamide polymers include liquid, dry, and emulsion. [Pg.249]


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Chloride Polymerization

Polymerization methods

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