Polymerization anionic ring opening

The ring-opening polymerization of oxiranes, thiiranes, and thietanes can be initiated by both cationic and anionic methods, but thrae are some heterocycUc compounds such as lactones and lactams that are more suited to the anionie technique. 

FIGURE 4.2 Behavior of the experimental propagation rate constant as a function of the concentration [E] of living ends for various salts of living polystyrene in tetrahydrofuran at 298 K. (From Szwarc, M., Carbanions, Living Polymers and Electron Transfer Processes, Interscience Publishers, 1968. With permission.) 

Polyethylene oxide is readily prepared by the reaction of ethylene oxide with the potassium salt of an alcohol, and the chain is terminated by a transfer reaction to excess alcohol present. 

Lactones can be used to prepare polyesters, but the ring size is an important consideration, e.g., the five-membered ring y-butyrolactone will not polymerize, whereas the six-membered ring 5-valerolactone reacts. 

Certain lactams will undergo ring-opening polymerizations to give polyamides, and nylon-6 can be prepared from the water-catalyzed reaction of caprolactam. 

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PA-5 can be synthesized by die anionic ring-opening polymerization of a-piperidone.12 First the catalyst, A -acetyl piperidone, is prepared. Then the polymerization is performed anionically, well below its melting temperature. 

Poly (dimethyl siloxane) obtained by anionic ring-opening polymerization of hexamethylcyclotrisiloxane (D3) can also be end-capped with vinylbenzyl bromide or other electrophiles, such as p. (chlorodimethylsilyl)styrene80). 

Suzuki, M. Kotani, J. Gyobu, S. Kaneko, T. Saegusa, T. 1994. Synthesis of sequence-ordered polysilane by anionic ring-opening polymerization of phenylno-namethycyclopentasilane. Macromolecules 27 2360-2363. 

Ring opening polymerization of hexasila[6](2,5)thiophenophane 49 was examined (46). Anionic ring opening polymerization of 49 with... 

As the first, and perhaps the most well-studied form of living polymerizations, anionic procedures have attracted considerable attention both academically and industrially [2, 3], While numerous examples of living procedures have been developed, they can be classified into two main families carbanionic polymerization of vinyl monomers and anionic ring opening polymerizations. 

For example, see Slomkowski, S. and Duda, A. Anionic ring-opening polymerization, In Ring-Opening Polymerization, Mechanisms, Catalysis, Structure, and Utility, Brunelle, D. J. (Ed.), Hanser-Verlag, New York, pp. 87-128, 1993. 

The first example of a catalytic reaction at the core of dendrimers was provided by Frechet (79) using dendritic alcoholates such as 86 as macro-initiators for anionic ring-opening polymerization of a-caprolactone. Usually the alkali... 

Mingotaud A-F, Dargelas F, Cansell F (2000) Cationic and anionic ring-opening polymerization in supercritical CO2. Macromol Symp 153 77-86... 

Kudoh R, Sudo A, Endo T (2009) Synthesis of eight-membered lactone having tertiary amine moiety by ring-expansion reaction of 1,3-benzoxazine and its anionic ring-opening polymerization behavior. Macromolecules 42 2327-2329... 

Barbaud C, Fay F, Abdillah F, Randriamahefa S, Guerin P (2004) Synthesis of new homopolyester and copolyesters by anionic ring-opening polymerization of a, a , P-trisubstituted P-lactones. Macromol Chem Phys 205 199-207... 

The typical anionic ring-opening polymerization involves the formation and propagation of anionic centers. Reaction proceeds by nucleophilic attack of the propagating anion on monomer ... 

Boileau, S., Anionic Ring-Opening Polymerizations Epoxides and Episulfides, pp. 467 487 in Comprehensive Polymer Science, Vol. 3, G. C. Eastmond, A. Ledwith, S. Russo, and P. Sigwalt, eds., Pergamon Press, London, 1989. 

Slomkowski, S. and A. Duda, Anionic Ring-Opening Polymerization, Chap. 3 in Ring-Opening Polymerization. Mechanism, Catalysis, Structure, Utility, D. J. Brunelle, eds., Hanser, Munich, 1993. 

Chemistry of Anionic Ring Opening Polymerization of Lactams. 8... 

Among the more common thermoplastics from ring opening polymerization of interest in composite processing are polylactams, polyethers, polyacetals, and polycycloolefins. It has also been shown that polycarbonates can be produced from cyclic carbonates [22], Anionic ring opening polymerization of caprolactam to nylon 6 is uniquely suited to form a thermoplastic matrix for fiber-reinforced composites, specifically by the reaction injection pultrusion process [23-25]. The fast reaction kinetics with no by-products and the crystalline... 

Anionic ring opening polymerization of lactams to generate polyamides has been studied quite extensively by Sebenda [8-10], Sekiguchi [11], and Wichterle [12-13], among others, in academia, and by Gabbert and Hedrick [14] and by us [23-25] in industry. By far, caprolactam is the most studied lactam and the nylon 6 prepared by this route compares favorably in properties with that prepared by conventional hydrolytic polymerization. 

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