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Interfacial condensation, polymerization

Interfacial or solution polycondensation, with or without stirring, was the general procedure utilized for the preparation of the polyamides and polyureas.l a Details are given in Table I. An important point to be noted is that, in the unstirred interfacial condensation polymerization of 1 with sebacoyl chloride or tere-phthaloyl chloride in the organic phase and triethylamine as the proton acceptor, immediate film formation took place at the interface. The polyamide films were removed after 1 h, dried, and utilized for taking electron micrographs. [Pg.438]

The ultrathin dense barrier layer and the thick porous underlayer can be separately fabricated from various materials and laminated together to give an asymmetric membrane. Thus a thin barrier membrane can be formed on the porous matrix by casting from a polymer solution, in-situ polymerization, or in-situ-interfacial condensation polymerization. [Pg.86]

Some all-aromatic poly (thiol esters) have also been prepared by this method (34). There is also a continuous process for interfacial condensation polymerization by which poly (thiol esters) with high inherent viscosities have been produced (27). [Pg.133]

The polymeric material is derived from the interfacial condensation polymerization between titanocene dichloride and 2-nitro-p-phenylenediamine (Figure 1). This product was initially synthesized by us in 1975 employing both the interfacial and solution polymerization techniques. [19]... [Pg.140]

The condensation polymerization process, employed recently by Skourlis et al. (1993) and Duvis et al. (1993), involves immersion of carbon fibers in a solution containing hexamethylenediamine and sodium carbonate. Dried carbon fibers are then immersed in a dipolychloride solution in carbon tetrachloride where the interfacial polycondensation reaction takes place. The result is that a thin layer of polyamide (nylon 6,6) coating is deposited on the continuous carbon fiber, whose thickness is controlled though by varying the diamine concentration. [Pg.295]

A second classical method for making capsules from emulsions is to form the shell polymer in situ using interfacial polymerization (Morgan and Kwolek 1959 Wittbecker and Morgan 1959). This method is similar to the nylon rope trick often used as a demonstration, where a solution of diacid chloride in organic solvent (such as adipoyl chloride in hexanes) is layered in a beaker with a diamine aqueous phase (such as 1,6-hexadiamine in water Friedli et al. 2005). Because the two monomers meet only at the interface of the two phases, the condensation polymerization to form the polyamide occurs only at the interface. [Pg.182]

In contrast to the interfacial oxidative condensation polymerization, where discharge of anions occurs at the growing end through the conductive polymer, a new cathodic process of formation of unstable monomers has been developed, followed by polymerization. [Pg.391]

Bis(hydroxymethyl) furan and 5-hydroxymethyl furfural (available from C6 sugars) have been oxidized to furan-2,5-dicarboxylic acid (44)- Linear polyesters, polyurethanes, and polyamides containing these monomers have been described in the literature (45-43) and have been made via condensation polymerization techniques including bulk, solution, and interfacial mixing procedures. Gandini (5,34) reviewed the poly condensation reactions up to 1986 and... [Pg.413]

Interfacial polycondensations can also be carried out in vapor-liquid systems. Reaction takes place at the interface between an aqueous solution of a bifunctional active hydrogen compound and the vapor of diacid chloride. Interfacial condensation is commercially important in the synthesis of polycarbonates (1-52). Polymerizations based on diacids are always less expensive than those that use diacid chlorides. In the polycarbonate case, however, the parent reactant, carbonic acid, is not suitable and the derived acid chloride, phosgene (COCI2), must be used. [Pg.183]

Encapsulation. Immobilization of enzymes by encapsulation within semipermeable structures dates back to the 1970s. There are three fundamental variations of this approach. In coacervation, aqueous microdroplets containing the enzyme are suspended in a water-immiscible solvent containing a polymer, such as cellulose nitrate, polyvinylacetate, or polyethylene. A solid film of polymer can be induced to form at the interface between the two phases, thereby producing a microcapsule containing the enzyme. A second approach involves interfacial polymerization in which an aqueous solution of the enzyme and a monomer are dispersed in an immiscible solvent with the aid of a surfactant. A second (hydrophobic) monomer is then added to the solvent and condensation polymerization is allowed to proceed. This approach has been used extensively with nylons, but is also applicable to polyurethanes, other polyesters, and polyureas. [Pg.1372]

Aliphatic or aromatic structure, as weU as liner or branched structure of the reactants, can give the microcapsule shell different porosity and permeability, which can greatly inflnence the release performances. Multifunctional reactants can help to achieve more thermal mechanical stable microcapsules since the wall is a three-dimensional cross-linked polymer network. Experiments have shown that dichlorides with less than eight carbon atoms do not prodnce qnahty polyamide microcapsules. The reason behind this is the competition between interfacial condensation and the hydrolysis reaction of dichlorides. More hydrophobic dichlorides can favor the polymerization and slow the hydrolysis. Similarly, for polyurethane and polyurea type microcapsules, polymeric isocy-nates are preferred because they might favor the formation of less permeable miCTocapsnles for the hydrolysis of isocynate groups are limited, which consequently reduced the COj release that contribute to the porosity increase of the polymer wall." ... [Pg.299]

Yan, L. Jiang, J. Zhang, Y. Liu, J. Preparation and characterization of large-size halloysite nanotubes particles by a combined technique of interfacial polymerization and condensation polymerization. Journal of Nanoparticle Research (2011), 13(12), 6555-6561. [Pg.303]

The most serious complication of conventional condensation polymerization is that only oligomers and very low polymers can be produced unless the reaction goes essentially to completion. One modification that suggests itself is that of interfacial polymerization 117). In such systems it is possible to obtain high molecular weight condensation polymers... [Pg.184]

The polymerization step is chosen appropriate to the monomers used and products produced. Solution pol3nnerization, interfacial condensation, and ester interchange can be used to produce polyesters for example. References 27 and 29 should be consulted to locate specific reaction conditions and methods for a given polymer class. [Pg.17]

Morgan,P.W. Condensation Polymeres By Interfacial and Solution Methods (Interscience Publishers,... [Pg.610]

Carraher recently reviewed these s3mtheses, emphasizing polymerizations employing the interfacial condensation technique. For the synthesis of poly-phosphonate and polyphosphate esters and amides Carraher, Millich and others have reported that hydrolysis of the acid chloride typically limits the product yield and molecular weight.The synthesis of polyesters ... [Pg.188]

Microcapsule Preparation by Interfacial Polymerization. The polymer forming the wall of the microcapsule can be made by addition or condensation polymerization or by in situ condensation polymerization. Addition polsrmerization using unsaturated monomers and free-radical-generating catalysts may start with the monomer in the pesticide-containing dispersed oil phase and the water-soluble catalyst in the aqueous phase. Other combinations of monomer and catalyst distributed between the two phases are possible but less practical. Pesticide impurities can interfere with the polymerization producing unsatisfactory capsules (26). [Pg.1839]

Condensation Polymerization of Phosphonyl Dihalides or Phosphoryl Dihalides with Diamines. Polyphosphonamides have been prepared by interfacial reaction of phenylphosphonic dichloride with diamines (99,144) these products have apparently not been commercialized. Polyphosphonic amides have been shown to have useful flame-retardant efficacy in polyolefin formulations with other phosphorus additives (145). [Pg.5574]

Purpose. The polyamide, nylon, is prepared by the step-growth condensation polymerization of adipoyl chloride with 1,6-hexanediamine. An interfacial (emulsion) polymerization technique is used to generate nylon... [Pg.464]

An important application in agrochemicals is that of controlled-release formulations. Several methods are used for controlled release, of which microcapsules (CS) are probably the most widely used. These are small particles with size range 1-1000 pm consisting of a core material and an outer wall. The latter isolates the core material from the environment and protects it from degradation and interaction with other materials. The core active ingredient is designed to be released in a controlled manner as required. Microencapsulation of agrochemicals is usually carried out by interfacial condensation, in situ polymerization or coacervation, all of which are determined by the interfacial properties. [Pg.167]

Microencapsulation of agrochemicals is mainly carried out by interfacial condensation, in situ polymerization and coacervation. Interfacial condensation [126,127] is perhaps the most widely used method for encapsulation in industry. The a.i., which... [Pg.261]

Effects of the solvent, polymerization time, intrinsic viscosity and pH on the degree of the specific rotation of polyhexamethylene-c -tartaramide were investigated. From the results of hydrolysis of the polymer, it was found that c/-tartaric acid is not racemized during condensation polymerization. Interfacial polycondensation of diamines with r/-tartaric acid derivatives failed. [Pg.29]

Morgan, P. M., Condensation Polymers By Interfacial and Solution Methods , Interscience, New York, 1965. A review of the field of condensation, polymerization and hydrogen transfer polymerizations carried out below 100 °C Polym, Rev., vol. 10). [Pg.1409]

The next approach used the int acial polycondensation reaction to form a vay thin polymeric layer onto a substrate. Morgan first proposed this approach (Morgan, 1965), and then Scala et al. (1973) and Van Heuven (1976) actually applied this approach to obtain an RO membrane. But it was Cadotte who invented the high-performance membrane using the in situ interfacial condensation method (Cadotte, 1985). In his method, interfacial condensation reactions between polymeric polyamine and monomeric polyfimctional acid halides or isocyanates takes place on a substrate material to deposit a thin film barrier onto a substrate. Some of the composite membranes were succeeded in industrial fabrication by another method, which was designated as PA-300 or RC-100. [Pg.7]

Polymerization may be carried out with monomer alone (bulk), in a solvent (solution), as an emulsion in water (emulsion), or as droplets, each one comprising an individual bulk polymerization, suspended in water (suspension). All four methods are commercially applied to radical-initiated chain polymers such as polystyrene. Most ionic and coordination complex systems are inactivated by water, so that only bulk or solution methods can be used. Also, rather few condensations are carried out in emulsion or suspension. However, ethylene dichloride and sodium polysulflde are condensed to give ethylene polysulflde rubber and sodium chloride in an aqueous emulsion. Gas-phase polymerization and interfacial condensation are special techniques, which are mentioned in Section 5.3. [Pg.190]


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See also in sourсe #XX -- [ Pg.435 , Pg.449 , Pg.451 , Pg.453 ]




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