Polymerization by condensation

The fate of silicic acid is of some interest. Silicic acid polymerizes, by condensation, and finally a silica gel is formed (Wilson Mesley, 1968). The insolubilization of silicic acid has been observed to parallel closely the precipitation of phosphate (Wilson Batchelor, 1967b) and is related to an increase of pH within the cement (Kent Wilson, 1969). A low concentration of silicic acid must remain in the matrix. All this is in accord with the known aqueous chemistry of silica. 

The thermal polymerization of /3-carboxymethyl caprolactam results in a novel polyimide which has been identified as a poly(2,6-dioxo-l, 4-piperidinediyl)trimethylene. The formation of this structure is explained by a mechanism that consists in an initial isomerization of the caprolactam derivative to 3-(3-aminopropyl)glutaranhydride or its linear dimer and subsequent polymerization by condensation involving the terminal amino group and the anhydride moiety. Suggested reaction schemes and corresponding kinetic equations are based upon the premise that the extent of polymerization is represented by the concentration of imide linkages. Results of rate studies carried out at 210°-290°C. support the proposed mechanism. 

Sol-gel processing describes a type of solid materials synthesis procedure, performed in a liquid and at low temperature (typically T< 100 °C). The development of sol-gel techniques has long been known for preparations of metal oxides and has been described many times [30-38, 40-46, 65]. The process is typically used to prepare metal oxides via the hydrolysis of reactive precursors, usually alkoxides in an alcoholic solution, resulting in the corresponding hydroxide. It is usually easy to maintain such hydroxide in a dispersed state in the solvent. Condensation of the hydroxide molecules with loss of water leads to the formation of a network When hydroxide species undergo polymerization by condensation of the hydroxy... 

Adipic acid and 1,6-diamino-hexane are the monomers that polymerize by condensation to iform nylon-6,6. You are probably familiar with nylon fabrics, such as those used to make tents, but nylon can be molded into solid objects too. 

Monosaccharides can be synthesized stereoselectively by sequences of Wittig reactions and Sharpless epoxidations (see Scheme 4.3.1). This is, however, usually not necessary, because a large selection of monosaccharides is commercially available. Carbohydrate reactions then only involve introduction of protecting groups and polymerization by condensation, e.g., formation of oligosaccharides (see Sec. 4.3.4) or polymeric phosphodiesters (nucleotides see Secs. 8.4.1 and 8.4.2). In all cases the condensation depends on the nucleophilic-ity of amino or hydroxyl functions and the electropositive character of carboxyl carbon or phosphate or phosphite phosphor atoms. 

Polymerizations were conducted, as shown in Scheme 2, by condensing the dialdehydes with p-phenylene diamine under toluene reflux, in which the water formed was removed out of the polymerization system. One monomer Cg-M was additionally polymerized by condensation in hexamethyl phosphoramide(HMPA)/N-methyl pyrrolidone(NMP) mixture without removing the water. Polymerization yields were practically quantitative. 

Another example of polymerization by condensation is the formation of polyamide (in our case Nylon 6-6) by reacting a di-acid with a diamine. 

It is also possible to polymerize by condensation a single monomer with two opposing groups at its ends. In the case of a polyamide. Nylon 6 can be polymerized from the monomer H2N(CH2)sCOOH... 

It is well known that phenol is polymerized by condensation with formaldehyde, as shown in Figure 3.15. Aldehyde is quite reactive with phenol by condensation. Similarly, m-methoxyphenol is reacted with 1,5-pentanediol to form noria, as shown in Figure 3.16. Details of the experimental method of noria formation are given below. ... 

Formaldehyde polymerizes by condensation with phenol and urea to form phenol— and urea— formaldehyde resins which are popular and inexpensive adhesives. They are paint and coatings often used in coatings when combined with alkyds, epoxides, polyesters, or acrylic to give strong flexible films. 

Epoxy coatings are two-part systems which, similar to the adhesive, polymerize by condensation to form a thermosetting film. There are basically three types of epoxy resins used in coatings ... 

The tendency for an oxoacid to polymerize by condensation is most marked in the less acidic (more highly hydroxylated) acids. There are many stable condensed forms of silicic and boric acid, whereas the condensed forms of phosphoric acid are unstable towards hydrolysis. 

Nylon A class of synthetic fibres and plastics, polyamides. Manufactured by condensation polymerization of ct, oj-aminomonocarboxylic acids or of aliphatic diamines with aliphatic dicarboxylic acids. Also rormed specifically, e.g. from caprolactam. The different Nylons are identified by reference to the carbon numbers of the diacid and diamine (e.g. Nylon 66 is from hexamethylene diamine and adipic acid). Thermoplastic materials with high m.p., insolubility, toughness, impact resistance, low friction. Used in monofilaments, textiles, cables, insulation and in packing materials. U.S. production 1983 11 megatonnes. 

The polymerization of j3-carboxymethyl caprolactam has been observed to consist of initial isomerization via a second-order kinetic process followed by condensation of the isomer to polymer ... 

Unsaturated polyester resins prepared by condensation polymerization constitute the largest industrial use for maleic anhydride. Typically, maleic anhydride is esterified with ethylene glycol [107-21-1] and a vinyl monomer or styrene is added along with an initiator such as a peroxide to produce a three-dimensional macromolecule with rigidity, insolubiUty, and mechanical strength. 

At equihbrium, the specific composition of a concentrated phosphoric acid is a function of its P2 s content. Phosphoric acid solutions up to a concentration equivalent of about 94% H PO (68% P2O5) contain H PO as the only phosphoric acid species present. At higher concentrations, the orthophosphoric acid undergoes condensation (polymerization by dehydration) to yield a mixture of phosphoric acid species (Table 5), often referred to genericaHy as polyphosphoric or superphosphoric acid, H20/P20 = - 3, or ultraphosphoric acid, H20/P20 = - 1. At the theoretical P2O5 concentration for orthophosphoric acid of 72.4%, the solution is actually a mixture containing 13% pyrophosphoric acid and about 1% free water. Because the pyrophosphoric acid present is the result of an equihbrium state dependent on the P2 5 content of the solution, pure orthophosphoric acid can be obtained because of a shift in equihbrium back to H PO upon crystallization. 

The molecular chains of plastics are formed by condensation or addition polymerization,. V condensation polymer forms by stepwise reacting molecules with each other and eliminating small molecules such as water. Addition polymer forms chains by the linking without elimin.ating small molecules,... 

Hydroxy-containing polymers such as poly(methyl-methacrylate-co-hydroxyethyl methacrylate) [65,66] or secondary cellulose acetate [67,68] were used for this purpose. Vanadium (V) 8-hydroxy quinoline-hydroxy-ethyl methacrylate adduct, prepared by condensation of the latter with a VOQ2OH complex, is polymerized to... 

Although no small molecule gets eliminated, the reaction can be considered a condensation polymerization. Monomers suitable for polymerization by ring opening condensation normally possess two different functional groups within the ring. Examples of suitable monomers are lactams (such as caprolactam), which produce polyamides, and lactons, which produce polyesters. 

Most big-volume thermoplastics are produced by addition polymerization. Other thermoplastics are synthesized by condensation. Table 12-1 shows the major thermoplastics. ... 

Thermoplastic polyesters are among the large-volume engineering thermoplastics produced by condensation polymerization of terephthalic... 

This group includes many plastics produced by condensation polymerization. Among the important thermosets are the polyurethanes, epoxy resins, phenolic resins, and urea and melamine formaldehyde resins. 

Polymerization involves the chemical combination of a number of identical or similar molecules to form a complex molecule of high molecular weight. The small units may be combined by addition polymerization or condensation polymerization. 

The well-known condensation between 2-furaldehyde and acetone in a basic medium yields what is usually called furfurylidene acetone monomer composed of a mixture of 2-furfurylidene methyl ketone, di-2-furfurylidene ketone, mesityl oxide and other oligomers derived from further condensation reactions135. This mixture is then polymerized by the action of an acidic catalyst in the first phase of the reaction a polymer of low molecular weight is produced which on further treatment cross-links to a black insoluble and heat-resistant material136. ... 

Reacts with acids to neutralize them. Prepn is. by reacting NaOH with Na in a nickel crucible at 320° under high vacuum. Yield is 96%. The oxide is stored under anhyd benz. It is also the product of the ignition of many of the sodium compds found in pyrots. It is used as a chemical reagent for organic polymerization or condensation reactions... 

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