Influence of the Supramolecular Organization on the Magnetic Properties of Poly(3-alkylthiophene)s in Their Neutral State

The influence of the supramolecular behavior on the magnetic properties of head-to-tail coupled poly(3-alkylthiophene)s (P3AT) is reported. Samples with a different molar mass were prepared, and differences in their behavior were illustrated by UV-vis and CD spectroscopy. In addition, tuning of the supramolecular organization was also accomplished by applying thermal annealing. ESR spectroscopy was performed on powder samples. From the line features, information on the nature of the unpaired spins, the mobility, and the supramolecular order of the sample was derived. These spins are paramagnetic. SQUID magnetometry, in contrast, shows for all samples a ferromagnetic behavior at 5 K and superparamagnetism at 300 K. The coercivity does not depend on the degree of supramolecular order but is inherent to the molecular structure and, related to this, the a-interactions. The saturation magnetization, on the contrary, seems to be mainly influenced by the fraction of planarized polymer chains.status: publishe