Volume 82, Number 2, April 2008
Article Number 28009
Number of page(s) 6
Section Interdisciplinary Physics and Related Areas of Science and Technology
Published online 11 April 2008
EPL, 82 (2008) 28009
DOI: 10.1209/0295-5075/82/28009

Conformational transitions of conjugated annealed polyelectrolytes

P. Vallat, J.-M. Catala, M. Rawiso and F. Schosseler

Institut Charles Sadron, ULP-CNRS, UPR22 - 23 Rue du Loess, BP 84047, F-67034 Strasbourg cedex 2, France, EU

received 21 December 2007; accepted in final form 2 March 2008; published April 2008
published online 11 April 2008

We study the collapse of hydrophobic annealed polyelectrolytes with a conjugated polythiophene backbone as a function of pH. The evolution of UV-visible absorption spectra suggests the existence of two conformational transitions: extended $\rightarrow$ collapsed $\rightarrow$ densely collapsed, and we measure the fraction of monomers in the three states as a function of neutralization degree. The first transition displays the qualitative features of the first-order transition predicted for hydrophobic annealed polyelectrolytes. The second transition is tentatively associated with the increase of H-bonding in the collapsed chains at low pH.

82.35.Rs - Polyelectrolytes.
78.40.-q - Absorption and reflection spectra: visible and ultraviolet.
05.70.Fh - Phase transitions: general studies.

© EPLA 2008