Structure-Magnetic Property Relationships in Radical Polymers

Interest in open-shell polymers capable of magnetic interactions has increased in recent years due to fundamental and applied efforts. Specifically, radical polymers present new opportunities as a novel class of macromolecules with a high number of open-shell groups along a single polymer chain. To this end, the magnetic behavior of poly(4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl) (PTEO) and its precursor materials, 4-hydroxy-2,2,6,6-tetramethylpiperidin-N-oxy (TEMPO-OH) and 4-glycidyloxy-2,2,6,6-tetramethylpiperidine-1-oxyl (TEO), were quantified. Magnetic susceptibility (X_m) measurements highlighted that TEMPO-OH, TEO, and PTEO had a X_m of  1.8×10^-2, 4.6×10^-2, and 1.3×10^-1 emu mol^-1, respectively at T = 2 K. Furthermore, all three materials showed antiferromagnetic interactions between the spins. Due to its amorphous nature, PTEO had weak antiferromagnetic interactions. However, thin films of PTEO doped with TEMPO-OH showed increased antiferromagnetic interactions between the open-shell sites. In this way, this effort elucidates the magnetic structure-property relationship of radical polymers.