High Magneto-Crystalline Anisotropic Core–Shell Structured Mn_0.5Zn_0.5Fe₂O₄/Polyaniline Nanocomposites Prepared by in Situ Emulsion Polymerization

Abstract

ferrite particles were synthesized by a reverse microemulsion reaction process. Core−shell nanocomposites composed of Mn 0.5 Zn 0.5 Fe 2 O 4 nanocrystals and conjugated polymer polyaniline were successfully synthesized from a simple and inexpensive process, and in situ chemical oxidative polymerization of aniline occurs. Mn 0.5 Zn 0.5 Fe 2 O 4 nanocrystals are in the micellar solution of dodecyl benzene sulfonic acid (DBSA). It acts as both a surfactant and a dopant. These nanocomposites were subsequently investigated for structural, morphological magnetic, and electromagnetic properties. Transmission electron microscopy (TEM) studies reveal the formation of core−shell type morphology with ferrite nanocrystals (∼9−11 nm) as the center, while the polymer (PANI) formulates the outer shell of the composite. A decrease in the blocking temperature of Mn 0.5 Zn 0.5 Fe 2 O 4 nanocrystals after coating with PANI has been recorded, attributing that the polymer matrix allows each ferrite nanoparticle to behave independently, indicating a decrease in the dipole−dipole interactions that will decrease the anisotropy energy barrier. Magnetic properties of the synthesized nanoferrite exhibit a very high magneto-crystalline anisotropy energy value of 31.3 × 10 5 erg/cm 3 at a blocking temperature of 90 K. The complex permittivity, permeability, and microwave absorption properties of the composites were explored in the 8.2−12.2 GHz (X-band) frequency range. The nanocomposites are observed to show high shielding effectiveness (SE A = 31.2 dB) as compared to pure PANI, which strongly depends on dielectric loss, magnetic permeability, and volume fraction of Mn 0.5 Zn 0.5 Fe 2 O 4 nanocrystals. The high value of SE A suggests that these composites can be used as a promising electromagnetic absorbing material.

Binary polyamide hybrid composites containing carbon allotropes and metal particles with radiofrequency shielding effect

“…This effect is usually achieved by the simultaneous incorporation of conductive, magnetic and/or dielectric fillers into a matrix that can be also polymeric . Novel structural RAM or EMI materials are attracting increasing interest from academia and industry due to their diverse applications in military stealth technologies, in aircraft and ship transports as well as in television for image interference reduction , and in medical diagnostic equipment , among others.…”

In Situ Doped Polyaniline Nanotubes for Applications in Flexible Conductive Coatings

“…Appearance and subsequent increase in the absorption peak at 1 194 cm −1 is associated with the vibration modes of NQN. The increased absorption is ascribed to the increase in PANI content with enhanced doping . The peak at 1 276 cm −1 is attributed to CH in‐plane bending mode.…”

“…Polyaniline (PANI) is one of the most promising electrically conductive polymers in various fields of electronics, such as sensors, electromagnetic interference shielding, super‐capacitors, diodes, and transducers . This polymer exhibits metallic behavior in terms of electrical, magnetic, and optical properties and retains the properties of conventional polymers such as flexibility and temperature‐dependent viscosity.…”

“…Different forms of PANI, such as nanoparticles, nanotubes, and nanowires, have been prepared by various physical and chemical synthesis methods. Physical methods include electro‐spinning and various deposition techniques, while chemical routes include interfacial polymerization, electrochemical polymerization, and emulsion polymerization …”

Magnetic and conducting composites of cobalt ferrite nanorods in a polyaniline matrix

“…Composites formed by magnetic nanoparticles (MNPs) embedded in a conducting polymer matrix are very interesting due to the capability of combine electrical conduction with magnetic properties . MNPs are very interesting materials, due to their many potential applications .…”