Radiofrequency characterization of polydimethylsiloxane – iron oxide based nanocomposites

Goethite nanorods as a cheap and effective filler for siloxane nanocomposite elastomers

“…This is a different approach from that recently published in which spherical iron oxide NPs were prepared and incorporated within a matrix consisting in a commercial silicone kit. 9 We used a polydimethylsiloxane-α-ω-diol (PDMS) of high molecular mass as matrix in which the goethite form of iron oxide as well-defined nanorods (size <100 nm) was incorporated by mechanical mixing as a disperse phase. The crosslinking of the composites was performed using high temperature peroxide radical initiator, which leads to chemically homogeneous samples.…”

GHz Properties of Magnetophoretically Aligned Iron-Oxide Nanoparticle Doped Polymers

“…The RF properties in the range 0.5−2.5 GHz of IONPs/ PDMS PNCs were tested by means of a reflection/transmission method based on coplanar waveguides (CWG). 21 Briefly, an electromagnetic wave at a given frequency was guided in a section of bare CWG and let impact on a second CWG covered with the PNC under investigation. The implemented RF setup is sketched in Figure 3a and more details on the measurement procedure have been given in the Supporting Information and in ref 21.…”

“…Promising filler materials to achieve these goals are represented by ferromagnetic and superparamagnetic NPs, namely iron-oxide NPs (IONPs), ,,− NiZnFe 2 O 4 NPs, core/shell Fe/SiO 2 NPs or Fe/ZnO NPs, Co x Ni 1– x NPs, and SnO 2 NPs . The peculiarity of these materials is that magneto-dielectric properties of the realized PNC depend on NPs intrinsic properties: doping of polymers with superparamagnetic NPs does not affect polymers’ μ r and induces an increase of ε r , whereas doping with ferromagnetic NPs acts on both ε r and μ r .…”

“…Here we report the RF properties in the GHz frequency range of PNCs based on a polydimethylsiloxane (PDMS) matrix doped with magnetically assembled arrays of colloidal IONPs. PDMS has been chosen as host material by virtue of its low dielectric and magnetic loss tangents, its compatibility with flexible electronics even in presence of NPs and its suitability as a support for pliable, conformal and stretchable RF devices. ,− The magnetic behavior of the IONPs allows the generation of ordered domains through exposition to static magnetic fields, with the assembly being more effective for bigger IONPs. Remarkably, the aligned IONPs regions are found to have an important role in increasing the PNC dielectric permittivity compared to pure polymer and to polymeric films containing randomly dispersed IONPs.…”

Magnetically active polymeric nanocomposites for two-photon stereolithography

“…Polymeric nanocomposites (PNCs) can also be exploited as a resist for optical or electron-beam lithography, allowing the fabrication of hybrid micro-structures having magnetic [2], high-luminescence [3,4], or conductive [5] features depending on the encapsulated NPs. In particular, iron oxide nanoparticles (IONPs) are very useful for PNCs synthesis by virtue of their biocompatibility and magnetic properties related to their type, size and shape [6][7][8][9]. Incorporating metallic NPs in a polymeric host matrix, however, lead to a reduced quality of the fabricated structures and lower optical transparency with respect to the blank polymer, mainly due to due to particles aggregation and their stochastic distribution [10].…”