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Breakthrough in Conducting Polymers: Polyaniline Shows Perfect Diamagnetism
Research into conducting polymers has unveiled a range of unique properties beyond their ability to conduct electricity. These materials are being investigated for a variety of applications, including light-emitting devices, electromagnetic interference (EMI) shielding, and anticorrosion coatings. Among their intriguing characteristics is the phenomenon of paramagnetism.
A research team at the University of Tsukuba has successfully synthesized a conducting polymer known as polyaniline, which exhibits perfect diamagnetic properties. This development allows the material to negate external magnetic fields, a trait commonly associated with superconductors rather than typical conducting polymers.
Traditionally, conducting polymers are characterized by their paramagnetic nature, which means they are only weakly attracted to magnetic fields. The discovery of diamagnetism in this case is significant, representing a crucial advancement in the pursuit of materials that fundamentally oppose the common paramagnetic behaviors of most conducting polymers. These findings have been documented in a paper published in The Journal of Physical Chemistry B.
In earlier research, the team at Tsukuba devised techniques for synthesizing a variety of conducting polymers. In their latest study, polyaniline was synthesized with iron sulfate, resulting in the manifestation of perfect diamagnetism—the capacity to entirely exclude external magnetic fields. This behavior is distinctive compared to the more typical paramagnetism observed in other conductive materials.
Using Superconducting Quantum Interference Device (SQUID) measurements, the researchers confirmed that the polyaniline’s magnetic susceptibility showed a gradual negative shift from about 100 K (-173°C), and it displayed perfect antiferromagnetism below 24 K (-249°C).
Unlike conventional conducting polymers that typically demonstrate pronounced temperature-dependent behaviors, where electrical conductivity decreases and resistance increases at lower temperatures, the polyaniline synthesized in this study displayed remarkably consistent resistance regardless of temperature fluctuations. Only under extreme low temperatures did a substantial decline in electrical conductivity become evident.
The revelation of perfect diamagnetism in polyaniline suggests a rare occurrence not found in standard organic or inorganic conductive materials. This sensation hints at the possibility of an unconventional mechanism driving this perfect diamagnetic state, potentially paving the way for innovative developments in the realm of conductive polymers.
More information: Hiromasa Goto et al, Perfect Diamagnetism of Polyaniline, The Journal of Physical Chemistry B (2024). DOI: 10.1021/acs.jpcb.4c05317
Citation: Successful development of a perfect diamagnetic conducting polymer (2024, October 28) retrieved 28 October 2024 from Phys.org
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