Helical diamagnetism of a polyaniline-based polynitroxyl radical/hydroxypropyl cellulose blend

Abstract

In this study, poly(m-aniline) was synthesized via Pd-catalyzed cross-coupling polycondensation (Buchwald–Hartwig coupling) and oxidized using m-chloroperoxybenzoic acid (Tokumaru reaction) to generate nitroxyl radicals on the mainchains. Furthermore, oxidized poly(m-aniline) was blended with hydroxypropyl cellulose, which is a helical liquid crystal polymer. The obtained blend polymer was characterized using polarizing optical microscopy, scanning electron microscopy, and optical spectroscopy. The magnetic properties of the blend polymer were investigated using electron spin resonance and a superconducting quantum interference device. The mainchain of oxidized poly(m-aniline) in the matrix formed a helical structure because hydroxypropyl cellulose served as a helical template. Consequently, the spins on the mainchain resulted in the formation of a helical structure, and the blend polymer exhibited a helical diamagnetic behavior.