Step-growth polymerization nylon

Step growth polymerization. Important polymers manufactured by step growth are polyamides (nylons), polyesters, and polyurethanes. 

The most common form of step growth polymerization is condensation polymerization. Condensation polymers are generally formed from simple reactions involving two different monomers. The monomers are difunctional, having a chemically reactive group on each end of their molecules. Examples of condensation polymerization are the formation of nylon 66, a polyamide, and of poly(ethylene terephthalate), a polyester. Because condensation poly-... 

Step growth polymerization can also take place without splitting out a small molecule. Ring-opening polymerization, such as caprolactam polymerization to nylon 6, is an example. Polyurethane formation from a diol and a diisocyanate is another step growth polymerization in which no small molecule is eliminated. 

The nylon 66 molecule shown in Fig, 1,11 is a thermoplastic polymer, created by the step growth polymerization of hexamine and adipic acid. The majority of commercial polymers are thermoplastics, which permits us to readily mold them to many useful shapes. 

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. 

The second type of reaction is called a condensation reaction because we condense two monomers into a longer unit, and at the same time we eliminate—expel—a small molecule. This is also called a step growth polymerization reaction. Nylon 6-6 is made of adipoyl chloride and hexamethylene diamine ... 

Free Radical Polymerization Interfacial Step-Growth Polymerization Synthesis of Nylon... 

This experiment is an example of a step-growth polymerization that takes place at the interface of two immiscible solutions. For this reaction, a diamine dissolved in water reacts with a diacid chloride that is dissolved in an organic solvent. Because neither of the monomers is soluble in the solvent containing the others reaction can occur only at die surface4 or interface between the two solutions. The product is a polyamide, either nylon-6,6 or nylon-6,10, depending upon the number of carbon atoms in the diacid chloride chosen. This activity works well either as a laboratory experiment or as a demonstration. 

Interfacial polymerization—A polymerization that takes place at the interface of two immiscible liquids. Usually it is a step-growth polymerization in which one monomer is soluble in one of the liquids, and the other monomer is soluble in the other liquid (e.g., nylon rope ). 

Step-growth polymerization, 22, 24-25, 23, 84-86, 86,90-92,114-115, 261 compared with chain-growth polymerization, 88-89, 88-89 interfacial polymerization, 91-92 laboratory activities on synthesis of nylon, 228-230 synthesis of polyesters in the melt, 231-233 synthesis of polyurethane foam, 234-237 molar mass and, 86, 86 polycondensation of poly ethylene terephthalate), 90-91 polymers produced by, 86 types of monomers for, 90 Stereochemistry, 28, 37-39,41-42, 70 tacticity, 103-105 Stereoisomers, 41 Stereoregularity, 70 Stiffness, 142, 261 Strain, 142-143, 261 Strength... 

Otto Bayer was aware of the work of Staudinger and Carothers. He was particularly impressed with the latter s discovery of polyamides and its implications for the fiber and textile industries. He knew that in the condensation (linear step-growth) polymerization used to prepare nylon and polyesters a small molecule, usually water, is formed and has to be removed. 

Carothers (du Pont) synthesizes the first aliphatic polyesters, establishes the principles of step-growth polymerization, and develops nylon 6,6 Julius Nieuwland develops the synthetic mbber called neoprene Poly(methylmethacrylate) (PMMA) is synthesized Hans von Chain and Sir Frank Whittle file patents for the jet engine Cathode ray tubes (CRTs) are invented by Allen B. Du Mont Ernest Ruska discovers the electron microscope magnification of 12,000 X... 

In step-growth polymerizations of commercial linear polymers the degrees of conversion are clo.se to unity. Thus, for linear nylons and polyesters, Mv//M is close to 2 as indicated by Eq. (5-36) with p =. ... 

Nylons are polyamides formed by step-growth polymerization. In Section 22.16A, we learned that nylon 6,6 can be prepared by the reaction of a diacid chloride and a diamine. Nylon 6,6 can also be prepared by heating adipic acid and 1,6-diaminohexane. A Br0nsted-Lowry acid-base reaction forms a diammonium salt, which loses H2O at high temperature. In both methods, each starting material has two identical functional groups. 

Nylon 6 is another polyamide, which is made by heating an aqueous solution of e-caprolactam. The seven-membered ring of the lactam is opened to form 6-aminohexanoic acid, the monomer that reacts with more lactam to form the polyamide chain. This step-growth polymerization thus begins with a single difunctional monomer that has two different functional groups, NH2 and COOH. 

Problem 30.17 The first synthetic fibers were prepared by the step-growth polymerization of HOOC(CH2)4COOH arxJ HOCH2CH2OH. Draw the structure of this polymer and suggest reasons why it is less suitable than either nylon 6,6 or PET for use in consumer products. 

Step-growth polymers, such as polyamides and polyesters, are prepared by reactions between difunctional molecules. Polyamides (nylons) are formed by step-growth polymerization between a diacid and a diamine polyesters are formed from a diacid and a diol. 

Synthetic polymers are used in a number of areas of life and range from the nylon used in various articles of clothing to the polyvinyl chloride (PVC) used in plumbing and other applications. Synthetic polymerization of organic monomers can take place by addition polymerization or by step-growth (condensation) polymerization. Polystyrene is a common product of addition polymerization, and nylon is a common product of step-growth polymerization. 

As a last point, let us consider how copolymerization relates to the polymer growth mechanism. Eirst, most step-growth polymerizations (e.g., the production of nylon 6/6 by the reaction of hexamethylene diamine with adipic acid) use two monomers to produce the final polymer. One can say that these are inherently copolymerizations. Considering... 

Both polyesters and nylon 6,6 are prepared by step-growth polymerizations. The activation energies for such reactions are of the order of 84 kJ/mol. It is therefore usual to employ elevated temperatures to accelerate these reactions. The step-growth polymerizations shown are characterized by polymeiiza-tion-depolymerization equilibria, with equilibrium constants given by... 

In this chapter, we shall examine the main feamres of step-growth polymerization, beginning with the simpler reactions that produce linear chains exclusively. This type of polymerization is used to produce some of the industrially important fibers such as nylon and terylene. A brief discussion of the more complex branching reactions follows to illustrate how the thermosetting plastics are fonned. 

The second type of step-growth polymerization involves the use of monomers with different functional groups in the same molecule, A-B type monomers. An example of this reaction is the production of nylon 11 from 11-aminoundecanoic acid. 

In bulk polymerization, the only components of the formulation are monomers and the catalyst or initiator. When the polymer is soluble in the monomer, the reaction mixture remains homogeneous for the whole process. Examples of homogeneous bulk polymerization are the production of low-density polyethylene (LDPE), general purpose polystyrene and poly(methyl methacrylate) produced by free-radical polymerization, and the manufacture of many polymers produced by step-growth polymerization including poly(ethylene terephthalate), polycarbonate and nylons. In some cases (e.g., in the production of HIPS and acrylonitrile-butadiene-styrene (ABS) resins), the reaction mixture contains a preformed... 

An entirely different procedure can be used to form graft copolymers by a step-growth polymerization [347]. Formaldehyde is condensed with either phenol, p-cresol, orp-nonyl phenol and the resin is attached to either nylon 6, nylon 6,6, nylon 6,10, or nylon 11 backbones. Initially, the formaldehyde... 

Step-growth polymerization A polymerization in which chain growth occurs in a stepwise manner between difunctional monomers, for example, between adipic acid and hexamethylenediamine to form nylon 66. Also referred to as condensation polymerization. 

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