Polymerization telomerization

This review summarizes different synthetic methods of obtaining either molecular or maeromolecular fluorinated telechelic compounds. These compounds may be obtained either by direct synthesis or by syntheses which need many steps. Thus, reactions of polycondensation, polymerization, telomerization, fluorination of oligomers or the use of functional initiators are described in detail. On the other hand, the emphasis is also focussed on the interest of each method of preparation. Specific properties (solubility, thermal stability, surface properties. ..) of the obtained fluorinated telechelic products are discussed with regard to modern industrial requirements. We can observe that the compounds obtained by recently developed methods may be listed in two classes those which exhibit better surface properties and those which have better thermal stability. 

Four chapters in this volume are addressed to the uses of chelated alkali metal complexes in various polymerizations, telomerizations, and polymer grafting applications. They fully cover all of the published work in these areas. There are, however, several general features based on our unpublished results which warrant a general discussion. These include the effect of catalyst ion pair structure on polymerization activity and polybutadiene microstructure, the effect of steric hindrance on catalyst activity, and the mechanisms for chain transfer. 

Chain-transfer polymerizations (telomerizations), which were developed to produce polymers of narrower molecular weight distributions than in conventional free-radical polymerization, of poly-N-isopropylacrylamide (PNIPAM), poly-N,N-dimethylacrylamide (PNDMAM), and poly-N- 3-(dimethylamino)propyl acrylamide... 

Telomerization. Polymerization of DAP is accelerated by telogens such as CBr, which are more effective chain-transfer agents than the monomer itself (65) gelation is delayed. The telomers are more readily cured in uv than DAP prepolymers. In telomerizations with CCl with peroxide initiator, at a DAP/CCl ratio of 20, the polymer recovered at low conversion has a DP of 12 (66). 

The history of iodine transfer polymerization may be traced back to telomerization experiments carried out in the 1940fs.26"3" Iodine-transfer... 

Although sulfonyl chlorides add readily to unactivated olefins, with vinylic monomers telomeric and/or polymeric products were observed. This difficulty has been overcome by carrying out the addition in the presence of catalytic amounts of CuCl2, so as to provide a general and convenient synthesis of /5-chlorosulfones (Asscher-Vofsi reaction)63. For the copper-catalyzed system a redox-transfer mechanism has been suggested in which the... 

Amiduri, B Boutevin, B. and Gramain, P Synthesis of Block Copolymers by Radical Polymerization and Telomerization. VoL 127, pp. 87-142. 

Multiphase homogeneous catalysis (continued) hydroformylation, 42 483-487, 498 hydrogenations, 42 488-491 metal salts as catalysis, 42 482-487 neutral ligands, 42 481 82 organic reactions, 42 495 0X0 synthesis, 42 483-487 ring-opening metathesis polymerization and isomerization, 42 492-494 telomerizations, 42 491-492 diols as catalyst phase, 42 496 fluorinated compounds as catalyst phase, 42 497... 

Although not a telomerization, it is mentioned here, that syndiotactic 1,2-polybutadienes were prepared in aqueous emulsions with a 7t-allyl-cobalt catalyst [33]. Similarly, chloroprenes were polymerized using aqueous solutions of [PdCl2(TPPMS)2] and [RhCl(TPPMS)3] as catalysts at 40 °C in the presence of an emulsifier and a chain growth regulator (R-SH, R=Cio-Cis) [35]. Despite the usual low reactivity of chlorinated dienes, these reactions proceeded surprisingly fast, leading to quantitative conversion of 10 g chloroprene in 2 hours with only 50 mg of catalyst (approximate TOP = 3500 h- ). 

Fluorinated radicals play a significant role in synthetic organo-fluorine chemistry, for example, in electrophilic radical addition to alkenes, single-electron transfer reactions (SET), telomerization of fluoroalkenes with perfluoroalkyl iodides, polymerization to fluoropolymers and copolymers, and thermal, photochemical and radiation destruction of fluorocarbons. Furthermore, such free radicals are of interest for studying structures, reaction kinetics and ESR spectroscopic parameters.38... 

Photolysis of this polymer gives radicals on which side chains can be formed, giving graft polymerization 122, 123, 153). Similarly the polymerization of styrene (152) or vinyl acetate (157) in the presence of bromotrichloromethane gives telomers carrying terminal bromine atoms and trichloromethyl groups. By ultraviolet irradiation (3500 A) in the presence of methyl methacrylate the carbon-bromine links are broken and block copolymers are formed. The telomerization of acrylonitrile and acrylic acid with bromoform is based on the same technique the end groups of both polyacrylonitrile and polyacrylic acid were photolyzed in the presence of acrylamide and afforded polyacrylamide blocks linked to polyacrylonitrile or polyacrylic acid blocks (164, 165). 

Combes, J. R. Guan, Z. DeSimone, J. M. Homogeneous Free-Radical Polymerizations in Carbon Dioxide. 3. Telomerization of 1,1-Difluoroethylene in Supercritical Carbon Dioxide. Macromolecules 1994, 27, 865-867. 

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