Monomer ring-opening polymerization

Cyclic method, selenium and tellurium purification via, 22 86 Cyclic molecules, synthetic, 24 35 Cyclic monomers, ring-opening polymerization of, 14 271 Cyclic monoterpenes, aroma chemicals,... 

The polymeric phosphazenes are treated in chapter (see Polyphosphazenes) A recent monograph covers the chemistry of polyphosphazenes (nomenclature, synthesis of cyclic monomers , ring opening polymerization, condensation polymerization, substitution, polymer properties, and applications more than 1000 literature citations). Other reviews have also been published recently. Sulfur-containing polyphosphazenes have also been described. ... 

Figure 24.1 Internal subunits of hyper-branched polymers obtained from (a) ABy monomers (ring-opening polymerization of 2-(3,5-dihydroxyphenyl)-l,3-oxazoline DBprey = 40-50% increasing with M )...

Scheme 6.2 Anionic, cationic chain-end and cationic activated-monomer ring-opening polymerization mechanisms for ethylene oxide.

The key initiation step in cationic polymerization of alkenes is the formation of a carbocationic intermediate, which can then interact with excess monomer to start propagation. We studied in some detail the initiation of cationic polymerization under superacidic, stable ion conditions. Carbocations also play a key role, as I found not only in the acid-catalyzed polymerization of alkenes but also in the polycondensation of arenes as well as in the ring opening polymerization of cyclic ethers, sulfides, and nitrogen compounds. Superacidic oxidative condensation of alkanes can even be achieved, including that of methane, as can the co-condensation of alkanes and alkenes. 

Table 5.8 Values for AH and AS for the Ring-Opening Polymerization, Reaction (5.FF), for Monomers with the Indicated Values of 1...

Nylon-6 is the polyamide formed by the ring-opening polymerization of S-caprolactam. The polymerization of S-caprolactam can be initiated by acids, bases, or water. Hydrolytic polymerization initiated by water is often used in industry. The polymerization is carried out commercially in both batch and continuous processes by heating the monomer in the presence of 5—10% water to temperatures of 250—280°C for periods of 12 to more than 24 h. The chemistry of the polymerization is shown by the following reaction sequence. 

HO—R—COOH, or an amino acid, H2N—R—COOH. In some cases, such monomers self-condense to a cycHc stmcture, which is what actually polymerizes. For example, S-caprolactam (1) can be thought of as the self-condensation product of an amino acid. Caprolactam undergoes a ring-opening polymerization to form another... 

The ring-opening polymerization of is controUed by entropy, because thermodynamically all bonds in the monomer and polymer are approximately the same (21). The molar cycHzation equihbrium constants of dimethyl siloxane rings have been predicted by the Jacobson-Stockmayer theory (85). The ring—chain equihbrium for siloxane polymers has been studied in detail and is the subject of several reviews (82,83,86—89). The equihbrium constant of the formation of each cycHc is approximately equal to the equihbrium concentration of this cycHc, [(SiR O) Thus the total... 

Pencek, S., Kubisa, P. and Matyjaszewski, K. Cationic Ring-Opening Polymerization of Heterocyclic Monomers. Vol. 37, pp. 1 —149. 

Much of the interest in ring-opening polymerizations stems from the fact that the polymers formed may have lower densities than the monomers from which they are derived (i.e. volume expansion may accompany polymerization).168-171 This is in marked contrast with conventional polymerizations which typically involve a nett volume contraction. Such polymerizations are therefore of particular interest in adhesive, mold filling, and other applications where volume... 

The ring-opening polymerization of ketene acetals (45, X=0) provides a novel route to polyesters and many examples have now been reported (Scheme 4.27). " "7 A disadvantage of these systems is the marked acid sensitivity of the monomers which makes them relatively difficult to handle and complicates characterization. This area is covered by a series of reviews by Bailey ct a/.177 228 ... 

Various methylene derivatives of spiroorthocarbonates and spiroorthocstcrs have been reported to give double ring-opening polymerization e.g. Scheme 4.36). Like the parent monocyclic systems, these monomers can be sluggish to polymerize and reactivity ratios are such that they do not undergo ready copolymerization with acrylic and styrenic monomers. Copolymerizations with VAc have been reported.170 These monomers, like other acetals, show marked acid sensitivity. 

A new form of template polymerization based on ring-opening polymerization of 4-methylcncdioxalane has been reported by Endo and coworkers (Scheme 8.15).220,221 For this system, the monomer is covalently bound and the daughter polymer is released from the template as a consequence of the polymerization process. 

ATRP has been widely used for the polymerization of methacrylates. However, a very wide range of monomers, including most of those amenable to conventional radical polymerization, has been used in ATRP. ATRP has also been used in cyclopolymerization (e.g. of 16flm364) and ring opening polymerization or copolymerization e.g. of 16T 115 366 and 162 67). ... 

Heterochain polymers produced by ring-opening polymerization contain the hetero-atoms in the main chain as well as in the monomer and the polymer chain competes with the monomer for the reaction with the propagating species. This competition leads to polymer transfer and back-biting reactions during the polymerization. Heterochain polymers are also susceptible to depolymerization by the ionic active species which are easily formed during processing. 

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