Copolymers condensation polymerization

Most of the compounds in this class have been prepared from preexisting crown ether units. By far, the most common approach is to use a benzo-substituted crown and an electrophilic condensation polymerization. A patent issued to Takekoshi, Scotia and Webb (General Electric) in 1974 which covered the formation of glyoxal and chloral type copolymers with dibenzo-18-crown-6. The latter were prepared by stirring the crown with an equivalent of chloral in chloroform solution. Boron trifluoride was catalyst in this reaction. The polymer which resulted was obtained in about 95% yield. The reaction is illustrated in Eq. (6.22). 

All monomers (Petrarch) used in this study were carefully fractionally distilled prior to use. The condensation polymerization was carried out at approximately 110°C and allowed to reflux for 4 hours after the addition of the sodium metal was completed. The high molecular weight copolymers were obtained after two precipitations from toluene into ethyl acetate. 

More recently, we have extended the use of the condensation polymerization method to include many other combinations of alkyl and aryl groups in both homopolymers as well as copolymers. Future systematic studies of these materials should provide valuable information on the structure/property relationships which are applicable to this class of polymers. 

Alternating copolymers, as illustrated in Fig. 5.8 b), are generally made by condensation polymerization of two different monomers. Such copolymers display regularity and are capable of crystallizing under the appropriate conditions. Examples of such copolymers include nylons 66 and 610, and various types of polyurethane. 

There are numerous bifunctional monomers used in condensation polymerization. Some of the more popular signature groups that turn up frequently are shown in Figure 22-3. Important copolymers made by condensation include epoxies, nylon, polyesters, polycarbonate, and polyimides. As always, there are exceptions, and one is Nylon 6 made by a ring opening reaction of caprolactam. All of these will be covered in the next two chapters. 

For the synthesis of block copolymers chain addition polymerization (ionic or radical) as well as condensation polymerization and stepwise addition polymerization can be used. 

A high molecular weight organic compound, natural or synthetic, whose structure can be represented by a repeated small unit, the monomer (e.g., polyethylene, isoprene and cellulose). Synthetic polymers are formed by the addition or condensation polymerization of monomers. If two or more different monomers are involved, a copolymer is obtained. Some polymers can be rubbers and some can be plastics. Plastics which are also high polymers can include both natural, or synthetic products but exclude rubber whether natural or synthetic. At some stage in its manufacture every plastic is capable of flowing under heat and pressure into the desired final shape. 

In summary, the acid-catalyzed condensation polymerization of sugars in methyl sulfoxide results in the formation of copolymers of the sugars with formaldehyde. The glycosyl residues probably occur in blocks, instead of being evenly separated by methylene bridges. The polymers are highly branched, and the glycosyl residues appear to be substituted in a random fashion. 

Synthesis, The first Fully alkyl/aryl-subsiiluted polymers were reported in 1980 via a condensation-polymerization route. In addition lo providing fully alkyl/aryl-Mihsiiuiled poly pliospha/enes. the versatility of ihe process has allowed the preparation of various functionalized polymers and copolymers. 

Block copolymers may also be made by condensation polymerization. Elastomer fibers are produced in a three-step operation. A primary block of a polyether or polyester of a molecular weight of 1000-3000 is prepared, capped with an aromatic diisocyanate, and then expanded with a diamine or dihydroxy compound to a multiblock copolymer of a molecular weight of 20,000. The oxidative coupling of 2,6-disubstituted phenols to PPO is also a condensation polymerization. G. D. Cooper and coworkers report the manufacture of a block copolymer of 2,6-dimethyl-phenol with 2,6-diphenylphenol. In the first step, a homopolymer of diphenylphenol is preformed by copper-amine catalyst oxidation. In the second step, oxidation of dimethylphenol in the presence of the first polymer yields the block copolymer. 

Another approach to block copolymers of the aromatic polyamide and coil polymer is the macroinitiator method the chain-growth condensation polymerization of 22a from a macroinitiator derived from coil polymer. A diblock... 

After the development of catalyst-transfer condensation polymerization of polythiophene, the block copolymer of polythiophene and PMA could be prepared more easily. As mentioned above, the vinyl-terminated polythiophene was first prepared. The vinyl group was converted to the 2-hydroxyethyl group by hydroboration, followed by esterification with 2-bromopropionyl bromide to give a macroinitiator for ATRP (Scheme 101)... 

Block copolymers were developed rapidly in the 1960s when living anionic polymerization was first utilized to synthesize triblock thermoplastic elastomers or elastoplastics. At the same time, step or condensation polymerization to produce thermoplastic polyurethanes, urea-urethane spandex fibers, and later more specialized materials, such as the semicrystalline polyester-polyether copolymers were developed [10]. Imide block or segmented copolymers utilizing... 

The alternating copolymers (PPOX-CAR and PMOX-CAR) are easily prepared by the Wittig condensation polymerization between the oxadiazole containing salt monomers and the carbazole dialdehyde. The copolymer, PPOXPV, composed of oxadiazole unit and phenylenevinylene unit, can be prepared by the same way as shown in Scheme 10. But the kinked PPOXPV copolymer is prepared in different synthetic pathway. Reaction of bis(2-bromo-5-hexyloxyben-zyl)-l,3,4-oxadiazole with p-divinyl benzene results in the formation of POOX-PV copolymer [69]. 

Segmented copolymers are usually synthesized by condensation polymerization reactions (5, 7, 9). The reaction components consist of a difunctional soft segment, the basic hard segment component, and a chain extender for the hard segment. 

Another common type of polymerization is condensation polymerization, in which a small molecule, such as water, is formed for each extension of the polymer chain. The most familiar polymer produced by condensation is nylon. Nylon is a copolymer, since two different types of monomers combine to form the chain a homopolymer is the result of polymerizing a single type of monomer. One common form of nylon is produced when hexamethylenediamine and adipic acid react by splitting out a water molecule to form a C—N bond ... 

Siloxane-containing block copolymers are often prepared by step-growth or condensation polymerization of preformed diftmctionalized siloxane oligomers with other diftmctionalized monomers or oligomers. Our current work (3, 4, 6-8) on siloxane chemistry includes the preparation of a number of functionalized oligomers, with emphasis on equilibration processes with the commonly available cyclic tetramer, octamethylcyclotetrasiloxane (D4), in the presence of a functionalized disiloxane or end blocker. 

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