Conformational transitions of conjugated annealed polyelectrolytesP. 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 collapsed 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