A new class of conducting polymers: fully conjugated gels of poly(octylthiophene).

Two categories of fully conjugated poly(octylthiophene) gels have been prepared from well-characterized small molecules for various crosslink ratios, R, and for different crosslink functionalities, f. These gels swell and can be doped. Their statistical structure is determined by the variable α= f.R. Gel fraction, swelling ratio and proton-NMR specific structural parameter display master curves of variations versus α. The state of deformation of gels swollen at equilibrium has been described. At temperatures lower than 170°C, the gels are weakly semi-crystalline. The states of crystallinity, observed at various temperatures depend on α. The conductivity of doped dry gels is governed by intermolecular hopping processes (model of hopping between conducting clusters) and is found to also depend on α. At room temperature, crystalline domains size, conducting domains size and macroscopic conductivity show a maximum for the gel prepared at α= 0.003, disclosing that these quantities are correlated.