Morphology and Magnetic Properties of Sulfonated Poly styrene-(ethylene-co- butylene)-styrene Triblock Copolymer/Iron Oxide Nanocomposites

摘要

Magnetic metal oxides in different forms are considered in applications that involve the phenomenon of electromagnetic (EM) wave absorption in the range of microwave frequencies, in particular, as radar active materials (RAM). As opposed to EM wave absorption in dielectric materials, advantages of magnetic RAM coatings are that they can be thinner and provide low frequency range performance. A macroscopic magnetic material can be divided into smaller regions called magnetic domains. Below a critical domain size, particles do not form domains but are single domain. The critical single domain (SD) sizes for magnetite and maghemite are 128 and 166 nm, respectively. As particle size decreases within the SD range a critical threshold is reached where there is no hysteresis. When this happens, the system becomes superparamagnetic. For iron oxides, the critical superparamagnetic size has been reported to be approximately below ～20 nm.