Initiation of cationic polymerization via oxidation of free radicals using pyridinium salts

Böttcher, Artur; Hasebe, Kiyoshi; Hızal, Gürkan; Yaǧcı, Yusuf; Stellberg, Peter; Schnabel, W.

doi:10.1016/0032-3861(91)90061-m

Cited by 89 publications

(62 citation statements)

References 7 publications

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“…The different free radical sources, such as ␣-radicals of vinyl ethers and epoxides, have been generated thermally, photochemically, and ionizing-radiatively. 1,4,11,12 In most of the earlier studies on ionizing radiation-induced cationic polymerization enhanced by various onium salts, the monomer and the onium salt are all dissolved in a polar or nonpolar solvent, and the experiments are carried out at very low temperature. Obviously, solvent effect is important to the cationic polymerization.…”

Section: Introductionmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10] Some iodoniums and sulfoniums irradiated with UV light were discovered not only to get Bronsted acids by direct photodecomposition but also to obtain carbenium via an electron transfer process to initiate cationic polymerization. This is because the many onium salts with a relative higher reduction potential can oxidize the ␣-free radical of vinyl ethers and epoxides with a lower oxidation potential.…”

Section: Introductionmentioning

confidence: 99%

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Radiation curing of collagen/divinyl ether enhanced by pyridinium salts

Jiang

Zhou

Zheng

et al. 2005

J of Applied Polymer Sci

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ABSTRACT:The radiation curings of collagen/divinyl ether enhanced by several nitrogenous onium salts having relatively stable nonnucleophilic anion (PF 6 Ϫ ) have been investigated. Results of glass transformation temperature (T g ) measurements and IR spectroscopy analysis and solvent extractions to the crosslinked polymer networks demonstrate that the curing reactions have been initiated by electron beam irradiation in the mixture system of collagen/ divinyl ether and onium salts under different atmosphere conditions. The experimental data show the presence of an approximating linear relationship between double bond conversion and gel fraction after the calculation of conversion from IR spectra in oligomer and the measure of gel content at different total radiation doses. Practical values approximate theoretical values in applying gelation theory of the relationship of gel fraction and double bond conversion. In comparison with the influence of different inhibitors, the curing reaction with pyridinium salts is a polymerization and crosslinking of cationic mechanism, but radicals play an important role in initiation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Radiation curing of collagen/divinyl ether enhanced by pyridinium salts

Jiang

Zhou

Zheng

et al. 2005

J of Applied Polymer Sci

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“…33 The pyridinyl radical formed in this way is very short lived. 12 Its decomposition according to following reaction occurs very rapidly.…”

Section: Characterizationsmentioning

confidence: 99%

“…This salt is not capable of initiating the free radical promoted cationic polymerization; this can be explained in terms of the quite different redox potentials (relative to SEC) of the three salts: À1:2 V (Ph 3 S þ ), 34 À0:2 V (Ph 2 I þ ), 35 and À0:7 V (EMP þ ). 12 Bromine-terminated poly(cyclohexene oxide) was characterized in detail by IR and 1 H NMR spectral measurement. The IR spectrum of PCHO-Br contains characteristic CO ester band and ether group of PCHO at 1733 and 1086 cm À1 , respectively.…”

Section: Characterizationsmentioning

confidence: 99%

“…[1][2][3][4][5][6][7][8][9][10] N-alkoxy pyridinium salts are effective initiators for the cationic polymerization of cyclic ethers such as cyclohexene oxide and vinyl ethers such as n-butyl vinyl ether. 11 Their photoactivity can be tuned to a broad wavelength range by the use of free radical sources, 12 charge transfer complexes 13 and photosensitizers. 14 Photosensitized cationic polymerization has attracted particular interest since the triggering of the initiation may be extended to much longer wavelengths, where pyridinium salts are transparent and photosensitizers such as benzoin and its derivatives, benzophenon, and acylphosphin oxides absorb the light.…”

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confidence: 99%

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Synthesis of Block Copolymers by Transformation of Free Radical Promoted Cationic Polymerization to Atom Transfer Radical Polymerization

Degirmenci

Toprak

2005

Polym J

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ABSTRACT:The transformations of free radical promoted cationic polymerization to atom transfer radical polymerization (ATRP) to form the block copolymers of cyclohexene oxide (CHO) with styrene (St) were performed. In the first step, bromine terminated poly(CHO)s (PCHO-Br) were prepared by free radical promoted cationic polymerization of CHO monomer in the presence of 2-oxo-1,2-diphenylethyl-2-bromopropanoate, shortly bromo benzoin, (B-Br) and an onium salt namely 1-ethoxy-2-methylpyridinium hexafluorophosphate (EMP þ SbF 6 À ) as the initiating system. The bromine functionalized polymers thus prepared were used as initiators in ATRP of St, in bulk, in conjunction with CuBr/2,2 0 -bipyridine as catalyst gave well-defined block copolymer of CHO and St. Block copolymer formations were evidenced by 1 H NMR and gel permeation chromatography (GPC) measurements.

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Formation of triphenylmethyl cation during the photolysis of phenylazotriphenyl methane: a laser flash photolysis study

1998

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The photolysis of phenylazotriphenyl methane (PAT) in dichloromethane and acetonitrile solution at and at 23¡C results in the j inc \ 347 nm formation of triphenyl methyl (trityl) radicals and trityl ions. The quantum yields in dichloromethane solution are and Trityl '(Ph. ions are assumed to be formed by electron transfer between radicals formed by the photodecomposition of PAT. The yield of trityl ions is signiÐcantly increased upon irradiation of PAT solutions containing also an onium salt (N-ethoxy-2methyl pyridinium hexaÑuorophosphate ; This is due to the oxida-(EMP`PF 6 ). tion of trityl radicals by EMP`ions. Trityl ions generated in this way were found to be capable of initiating the cationic polymerization of cyclohexene oxide.1998 SCI.

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Initiation of cationic polymerization via oxidation of free radicals using pyridinium salts

Cited by 89 publications

References 7 publications

Radiation curing of collagen/divinyl ether enhanced by pyridinium salts

Radiation curing of collagen/divinyl ether enhanced by pyridinium salts

Synthesis of Block Copolymers by Transformation of Free Radical Promoted Cationic Polymerization to Atom Transfer Radical Polymerization

Formation of triphenylmethyl cation during the photolysis of phenylazotriphenyl methane: a laser flash photolysis study

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