Chromatographic investigations of polyacetals in the critical range of liquid chromatography, 2. Determination of functionality and molecular weight distributions in α,ω-bis(9-anthrylmethylpoly(1,3,6-trioxacyclooctane))s obtained by “active chain-end mechanism”
✍ Scribed by Valeria B. Gancheva; Nikolai G. Vladimirov; Rumiana S. Velichkova
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 487 KB
- Volume
- 197
- Category
- Article
- ISSN
- 1022-1352
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✦ Synopsis
Abstract
The fractions obtained by cationic active chain‐end polymerization of 1,3,6‐trioxacylooctane initiated with (CF~3~SO~2~)~2~O (I), CF~3~SOOCC~6~H~4~CO^⊕⊖^O~3~SCF~3~( II) and (C~6~H~5~)~3~C^⊕^PF (III) were investigated using high‐performance liquid chromatography (HPLC) at the “critical point” of adsorption. The propagating species were converted into 9‐anthrylmethyl groups by suitable reactions of termination of transformation. Their incorporation made the chain ends detectable in the ultraviolet spectrum. The samples were separated at conditions specified for poly(1,3,6‐trioxacyclooctane)s (polyTOCs) obtained with (CF~3~SO~2~)~2~O as initiator. The functionality and molecular weight distribution of polyTOCs obtained with mono‐ and bifunctional initiators and with different counterions were compared and discussed. In the reaction mixtures oligomers of undesired functionality were detected irrespective of the usage of mono‐ or even bifunctional initiators. A correct method was used to determine the completeness of the separation and to calculate the percentages of the individual fractions. The order of initiators depending on the amount of the undesired end‐functionality fractions in the products obtained has been established. Attempts were made to elucidate the reactions complicating the cationic chain‐end polymerization of cyclic acetals and leading to a mixture of cyclic, dead, monofunctional and bifunctional oligomers and polymers. The results were summarized and compared with functionality and molecular weight distributions of oligo(1,3,6‐trioxacyclooctane)s obtained by “activated monomer mechanism” which have been discussed in the first paper of this series.