ISSN:
0887-624X
Keywords:
Chemistry
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The radical polymerizations of diallylsilanes such as diallyldimethylsilane (1) and diallylmethylphenylsilane (2) have been conducted. Both poly(diallyldimethylsilane) (3) and poly(diallylmethylphenylsilane) (4) are soluble in benzene, methyl ethyl keton (MEK), and chloroform, slightly soluble in acetone, and insoluble in methanol and ethanol. No insoluble fraction of either polymer was obtained. Very little evidence of vinyl protons in the 1H-NMR spectra can indicate that both polymerizations predominantly proceed with intramolecular cyclization. In order to study the ring size of cyclic structure in the repeating unit of the polymers, a model compound, allyl(2-chloropropyl)dimethylsilane (5), was synthesized and cyclized with Bu3SnH in the presence of azobisisobutyronitrile (AIBN) in benzene, under similar condition of those for the cyclopolymerizations. The product was analyzed with GC-MS which showed that the five-membered ring compound, 1,1,3,4-tetramethylsilacyclopentane, was not formed. From the result of the cyclization of the model compound, it can be suggested that the polymerizations undergo with only h-t intramolecular cyclization to form a six-membered ring in the repeated unit. The 13C-NMR spectra of 3 and 4 were measured to study the ring size and the configuration of the cyclic structures. The two peaks at -1.6 and -3.4 ppm of the spectrum of 3 show that there are two kinds of methyl carbons in the repeating unit. From consideration of the model reaction and the number of the peaks of the NMR spectrum, it can be considered that the polymer main chain is assembled with the six-membered ring in cis-form, and the two signals are assigned to equatorial and axial methyl carbons, respectively. The two peaks at -1.5 and -5.1 ppm of the 13C-NMR spectrum of 4 can be assigned similarly. The radical cyclopolymerizations of triallylsilanes such as methyltriallylsilane (6) and phenyltriallylsilane (7) were conducted. The 1H-NMR spectra of poly(methyltriallylsilane) (8) and poly(phenyltriallylsilane) (9) show broad peak around 5 ppm for vinyl protons and around 2 ppm for alkyl protons. Comparisons of the relative intensities of the peaks indicate that both polymerizations undergo with single ring closure to form a polymer with monocyclic structure moiety, cyclosilahexane, and an allyl group in a repeating unit of 8 and 9.
Additional Material:
7 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pola.1988.080260808
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