Superparamagnetic Polymer Nanocomposites with Uniform Fe₃O₄ Nanoparticle Dispersions

Abstract

Magnetic nanoparticles embedded in polymer matrices are good examples of functional nanostructures with excellent potential for applications such as electromagnetic interference shielding, magneto‐optical storage, biomedical sensing, flexible electronics, etc. Control over the dispersion of the nanoparticle phase embedded in a polymer matrix is critical and often challenging. To achieve excellent dispersion, competition between polymer–polymer and polymer–particle interactions have to be balanced to avoid clustering of particles in polymer nanocomposites. We report the first deposition of magnetic nanocomposite poly(methyl methacrylate)/polypyrrole bilayers from solution using spin‐coating. Fe3O4 nanoparticles have been synthesized using a chemical co‐precipitation route. Using a combination of dissolving the polymer and mixing fatty acid surfactant coated Fe3O4 nanoparticles, we have demonstrated the formation of nanocomposites with uniform nanoparticle dispersion. Cross‐sectional scanning electron microscopy, transmission electron microscopy, and magnetic measurements confirm the excellent dispersion and superparamagnetic response. Low‐frequency impedance measurements on these bilayers are also presented and analyzed.

Morphological Characterization of Graphene Flake Networks Using Minkowski Functionals

“…Morphological parameters of the networks of nanostructures on surfaces and in nanocomposites directly influence many important characteristics of the whole structure such as electric resistance [1], thermal conductivity [2], percolation threshold [3], mechanical strength [4], optical [5] [6], electronic [7] and magnetic [8] [9] properties. Among others, networks of vertically-aligned few-layered graphene flakes [10] and graphene-polymer nanocomposites [11] attract a special interest due to extraordinary mechanical, electrical, magnetic and other properties of these systems [12]- [14], and morphological features of such networks also significantly affect their properties.…”

Magnetic silica:epoxy composites with a nano- and micro-scale control

“…Combining low density polymers with nanoparticles seems to be a good strategy to transfer the properties of the reinforcement (mechanical, electrical, magnetic, thermal, etc) to the global material. For example, improved electrical and mechanical properties have been achieved when introducing small amounts of carbon nanotubes in polymer matrices [1,2], epoxies loaded with nano and micro silica particles have shown enhanced mechanical properties and wear resistance [3,4], and multifunc tional nanostructured coreeshell magnetic nanoparticles having giant magnetoresistance sensing ability or microwave absorption properties [5] could lead to composites with potential applications as magneto optical modulators [6], biocompatible membranes for sensing [7] or as electromagnetic (EMI) shielding materials [8] when embedded in polymer matrices.…”

Self-Assembly and Photopolymerization of Diacetylene Molecules on Surface of Magnetite Nanoparticles

“…Magnetite (Fe 3 O 4 ) nanoparticles were synthesized using a chemical coprecipitation method which was reported elsewhere. [18][19][20] Briefly, ferrous chloride tetrahydrate (3.16 mmol) and ferric chloride hexahydarate (6.78 mmol) were added to deionized water (20 mL) and heated to 80 °C under nitrogen in a threenecked, round-bottomed flask, while magnetically stirring the mixture. Ammonium hydroxide solution (5 mL; 28%) was injected into the mixture.…”