Esters polymerization

The most important side reactions are disproportionation between the cobalt(ll) complex and the propagating species and/or -elimination of an alkcnc from the cobalt(III) intermediate. Both pathways appear unimportant in the case of acrylate ester polymerizations mediated by ConTMP but are of major importance with methacrylate esters and S. This chemistry, while precluding living polymerization, has led to the development of cobalt complexes for use in catalytic chain transfer (Section 6.2.5). 

Methacrylate double bond, 16 238 Methacrylate esters, polymerization of, 14 258... 

Methyl acrylate in methyl alcohol is available from Rohm and Haas Company, Philadelphia, Pa. Since the ester polymerizes in the presence of peroxides, it is necessary to add some hydroquinone as an inhibitor. The ester should not be stored for long periods of time, even when it contains hydroquinone. Storage should be in a refrigerator. 

Kowalski A, Duda A, Penczek S (1998) Kinetics and mechanism of cyclic esters polymerization initiated with tin(II) octoate, 1 Polymerization of e-caprolactone. Macromol Rapid Commun 19 567-572... 

Trollsas M, Lowenhiehn P, Lee VY, Mbller M, Miller RD, Hedrick JL (1999) New approach to hyperbranched polyesters self-condensing cyclic ester polymerization of bis (hydroxymethyl)-substituted e-caprolactone. Macromolecules 32 9062-9066... 

Tin(II) 2-ethylhexanoate is an important industrial initiator for cyclic ester polymerization [Duda and Penczek, 2001 Kricheldorf et al., 2001 Storey and Sherman, 2002]. Metal car-boxylates are useful initiators only in the presence of alcohols. The polymerization rate is very slow in the absence of alcohol, less than 1% of the rate in the presence of alcohol. The actual initiator is the metal alkoxide formed by the reaction between metal carboxylate and alcohol. 

An interesting exception reported by Rogovin and Tsaplina concerns vinyl acetate which when exposed to the influence of nitric esters, polymerizes very slowly. The ester radicals -N02, -ONC>2 and ions NO , ONO , do not seem to influence appreciably the rate of polymerization and the catalytic action of nitric esters is not produced by the presence of O—N02 groups. 

Fadner (42) reported preliminary results of electrically initiated polymerization experiments where liquid vinyl monomers are isolated from the electrodes. Liquid ethyl acrylate, for example, absorbed on a filter paper was polymerized in an alternating electric field. The filter paper was sandwiched between two layers of 1.5-mil Mylar film and placed between flat, parallel aluminum electrodes. Conversions of monomer to polymer ranged from 10 to 85% in the range between 20 and 240 sec at up to 25 kcps power. Acrylic acid and its ester polymerized most readily, others, such as styrene and vinyl chloride, resulted only in low yields in the same condition. 

Duda A Penczek S (2001) Thermodynamics, kinetics, and mechanisms of cyclic esters polymerization. In Polymers from renewable resources, vol 764. American Chemical Society, pp 160-198... 

The influence of a surface on the course of a polymerization reaction was discussed by Carothers (69) in 1936. He pointed out that in bulk solution the amino acids or their esters polymerize mainly to the cyclic dimers, the diketopiperazines. In living cells, however, these cyclic compounds are evidently not formed reaction is exclusively intermolecu-lar leading to the formation of linear polyamides. Carothers suggested that adsorption at a fat-water interface may well be responsible for this, since here the reactant monomer molecules will be oriented to lie flat in the plane of the surface. As an example, the molecule NH2 CH2-CO-NH-CHs COOH is anchored to the interface through the polar groups at each end and in the middle of the molecule. Under these conditions the difficulty of bending may prevent cyclization. 

The methods applied for the synthesis of 8-lactones are very similar to those described for y-lactones. In general, the tendency to form a six-membered ring is slightly lower than that for y-lactonization. This is illustrated by equation (114) 8-hydroxy esters polymerize on acid treatment. Depolymerization takes... 

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