Low Loss Polymer Nanoparticle Composites for Radio Frequency (RF) Applications

The aim of this research is to develop novel polymer nanocomposites with desired magneto-dielectric properties including high dielectric permittivity, high magnetic permeability, and low energy loss at radio frequencies. Block copolymer-templated and surface-modified magneto-dielectric nanoparticles were utilized because of their ability of uniform dispersion and ordering within the polymer matrices. The influence of intrinsic chemical composition and characteristic lengths (shape and size) of the doped nanoparticles on the resultant composites' magneto-dielectric properties was investigated. Well-dispersed high-dielectric-permittivity titanium dioxide nanoparticles were synthesized utilizing a block copolymer as a template. The nanoparticles were confined within microphase separated domains of sulfonated styrene-b-(ethylene-ran-butylene)-b-styrene block copolymers. A crosslinker (vinyltrimethoxysilane) was incorporated into the block copolymer matrices in order to decrease the dielectric loss from the free sulfonic acid groups. Dynamic mechanical analysis experiments confirmed that nanoparticles and crosslinker were confined within the crosslinked sulfonated styrene blocks and had no effect on the chain relaxation behavior of [ethylene-ran-butylene] blocks. Dielectric experiments showed that higher dielectric permittivity composites can thus be obtained with a significant decrease in loss tan delta (