Ring-opening polymerization cyclic amide

In addition to step and chain polymerizations, another mode of polymerization is of importance. This is the ring-opening polymerization (ROP) of cyclic monomers such as cyclic ethers, acetals, amides (lactams), esters (lactones), and siloxanes. Ring-opening polymerization is of commercial interest in a number of systems, including the polymerizations of ethylene oxide... 

Ring-Opening Polymerization of Cyclic Amides (Lactams)... 

Tam et al. (1). Ring-opening polymerization of cyclic amides using this agent are also reported by Tam et al. (2). 

Cyano compounds liquid crystals, 12, 278 in silver(III) complexes, 2, 241 Cyanocuprates, with copper, 2, 186 Cyano derivatives, a-arylation, 1, 361 Cyanosilanes, applications, 9, 322 Cyclic acetals, and Grignard reagent reactivity, 9, 53 Cyclic alkenes, asymmetric hydrosilylation, 10, 830 Cyclic alkynes, strained, with platinum, 8, 644 Cyclic allyl boronates, preparation, 9, 196 Cyclic allylic esters, alkylation, 11, 91 Cyclic amides, ring-opening polymerization, via lanthanide catalysis, 4, 145... 

Ring-opening polymerization of cyclic esters and amides... 

Besides cyclic esters and carbonates, six-membered cyclic depsipeptides and a five-membered cyclic phosphate were subjected to lipase-catalyzed ring-opening polymerizations, yielding poly (ester amide)s190 and polyphosphate,191 respectively. High temperatures (100—130 °C) were required for the polymerization of the former monomers. 

H. Sekiguchi, Lactams and Cyclic Amides, Chap. 12 in Ring Opening Polymerization, Vol. 2, (K. J. Ivin and T. Saegusa, eds.), Elsevier, London (1984). 

Lactams are cyclic amides formed by the intramolecular amidation of amino acids. The ring-opening polymerization of lactams [Eq. (10.34)], especially caprolactam (m = 5), provides a valuable noncondensation route to the synthesis of nylons q... 

With the development of polymer science and synthesis of newer polymers, this definition of condensation polymer was found to be inadequate. For example, in polyurethanes, which are classified as condensation polymers, the repeat unit has the same net composition as the two monomers-that is, a diol and a diisocyanate, which react without the elimination of any small molecule. Similarly the polymers produced by the ring-opening polymerization of cyclic monomers, such as cyclic ethers and amides, are generally classified as condensation polymers based on the presence of fimctional groups, such as the ether and amide linkages, in the polymer chains, even though the polymerization occurs without elimination of any small molecule. 

T. Fey, H. Keul, H. Hbcker, Ring-opening polymerization of the cyclic ester amide derived from adipic anhydride and l-amino-5-pentanol. Macromolecules 36 (2003) 3882-3889. 

Figure 2. In situ generation of a calcium alkoxide from bis(tetrahydrofuran)calcium, bis[bis(trimethylsilyl)amide] and an alcohol, for the ring Opening polymerization of cyclic esters...

Class 1 nylons are usually polymerized from a stoichiometrically balanced condensation reaction of a diacid with a diamine. Nylon 6,6 is the most common and is used in fiber, specialty plastic, and electrical applications. Class 2 nylons are usually synthesized from the ring-opening polymerization of cyclic amides or lactams. For instance, nylon 6 is polymerized from -caprolactam. Cyclic aliphatic polyamides normally have better thermal stability than their linear counterparts. 

Cationic and anionic polymerizations of heterocyclic monomers provide many examples in which the concurrent formation of cyclics of various sizes is observed during the ring-opening polymerization. As illustrated in Scheme 1, in these systems active species follow three pathways they can react with a functional group of the monomer, of its own polymer chain, or of other chains. When the function / involved belongs to a linear polymer chain, intramolecular chain saambling or intermolecular macrocycle formation takes place, as observed in the cationic polymerization of cyclic ethers, acetals, esters, amides, siloxanes, and so forth. 

The third method of polymer preparation involves a ring-opening polymerization (ROP) of cyclic monomers to polymeric chains. Thus, monomers such as ethylene oxide, propylene oxide or even tetrahydrofu-ran can be used as monomers for ROP. Cyclic amides (lactams) and cyclic esters (lactones) can also be polymerized. It is important to note that all cyclic organic compounds cannot be converted into linear chains. For example, well-known organic molecules such as benzene, cyclohexane, di-oxane, tetrahydropyran etc., cannot be polymerized to the corresponding... 

Production of poly(alkylene hydrogen phosphates) can be accomplished by ring-opening polymerization of cyclic hydrogen phosphonates, followed by oxidation (for example by chlorination and hydrolysis). The intermediate chloride can also be converted to esters or amides (111). 

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