ISSN:
0449-296X
Keywords:
Physics
;
Polymer and Materials Science
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The steric structure of poly(methyl propenyl ether) obtained by cationic polymerization was studied by NMR spectra. From the analysis of β-methyl and α-methoxyal spectra, it was found that the tacticities of the α-carbon were different from those of the β-carbon in all polymers obtained. In the crystalline polymers obtained from the trans isomer by homogeneous catalysts, BF3·O(C2H5)2 or Al(C2H5)Cl2, and from the cis isomer by a heterogeneous catalyst, Al2(SO4)3-H2SO4 complex, the structure of polymers was threo-di-isotactic. Though the configurations of all α-carbons were isotactic, a small amount of syndiotactic structure was observed in the β-carbon. On the other hand, in the amorphous polymer obtained from cis isomer by the homogeneous catalyst, the configuration of the α-carbon was isotactic, but that of the β-carbon was atactic. These facts suggest that the type of opening of a monomeric double bond is complicated, or that carbon-carbon double bond in an incoming monomer rotates in the transition state. From these experimental results, a probability treatment was proposed from the diad tacticity of α,β-disubstituted polymers. It shows that the tacticity is decided by a polymerization mechanism different from that proposed by Bovey.
Additional Material:
6 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pol.1968.150061106
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