Stabile polyphenoxyle, 5. Sterisch gehinderte vinylphenole zur spinmarkierung von polymeren
✍ Scribed by Braun, Dietrich ;Törmälä, Pertti ;Wittig, Wolfgang
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1981
- Weight
- 384 KB
- Volume
- 182
- Category
- Article
- ISSN
- 0025-116X
No coin nor oath required. For personal study only.
✦ Synopsis
Abstract
Polystyrene chains containing different amounts of 2,6‐di‐tert‐butyl‐4‐vinylphenylacetat repeating units were deacetylated and dehydrated by means of lead dioxide or potassium hexacyanoferrate(III) to obtain polystyrene molecules containing different amounts of phenoxyl spin‐label radicals. The inter‐ and intramolecular interactions between radical moieties were studied by varying the concentrations of polymer molecules in benzene and toluene solutions and the amounts of radical units in polymer chains. The source of information of these interactions was linewidth analysis of electron spin resonance (ESR) spectra which was carried out by spectral simulations. It was shown that the linewidths of ESR spectra of spin‐labelled polystyrenes in benzene and toluene solutions practically did not change when T > 40°C. It was found that intermolecular interactions are excluded if the polymer concentration is below 250 mg/l. The intramolecular interactions were first observed when the radical concentration in polymer chains was 0,7 mole‐%. This corresponds to a mean distance of 125 repeating units between the radical moieties or a nominal distance of radical units along the polymer chains of about 400 Å. However, the spin‐spin interaction shows that the distance between radicals is at the most about 100 Å under the studied conditions. This is a consequence of random coil conformation of polymer chains in solution.