Anomaly in magnetic properties of poly(3-alkylthiophene)s depending on alkyl chain length

The influence of the alkyl side-chain length exerted on the magnetic properties of poly(3-alkylthiophene)s, i.e. poly(3-dodecylthiophene) (PDDT) and poly(3-hexadecylthiophene) (PHDT), has been studied. The temperature dependences of the magnetic susceptibility and EPR signal have shown that PDDT displays some antiferromagnetic properties at the Néel temperature of 237 K. However, these properties were unnoticed for PHDT. The anomaly in the magnetic properties of PDDT and PHDT is discussed within the scope of differences in the crystalline phase of polymer derivatives brought about by a different alkyl side-chain length.