Electron microscopy studies on the coil-to-globule transition of a polyelectrolyte in a water–acetone mixture
✍ Scribed by Vladimir O. Aseyev; Jyrki Juhanoja; Heikki Tenhu; Stanislav I. Klenin
- Publisher
- John Wiley and Sons
- Year
- 1999
- Tongue
- English
- Weight
- 274 KB
- Volume
- 37
- Category
- Article
- ISSN
- 0887-6266
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✦ Synopsis
A high molar mass polycation poly(methacryloylethyl trimethylammonium methylsulphate), PMETMMS, dissolved in mixtures of water and acetone, was studied using light scattering during the reversible coil-to-globule transition. When the mass fraction of acetone in the solvent mixture, ␥, is higher than 0.80, PMETMMS adopts a globular state but does not aggregate. The collapse of PMETMMS can also be induced by the dilution of the polymer solution, if 0.70 Յ ␥ Ͻ 0.80, and the solvent composition is kept constant. The results obtained by light scattering have been confirmed using a transmission electron microscope with which the collapse of PMETMMS has been observed. At high polymer concentration and 0.70 Յ ␥ Ͻ 0.80, a transient network is formed: coils strongly interact with each other via dipole-dipole interactions in a thermodynamically poor solvent. At low concentration regime when 0.70 Յ ␥ Ͻ 0.80, or in solutions with the mass fraction of acetone higher than 0.80, all the PMETMMS molecules are collapsed. In the intermediate region, the collapse of PMETMMS is gradual and coils, globules, as well as fragments of the network coexist in the solution.