Electrical properties of nanocomposites based on comb-shaped nematic polymer and silver nanoparticles

A nematic comb-shaped copolymer and its nanocomposites containing 0.063-0.54 in vol % of silver nanoparticles were studied by broadband dielectric spectroscopy. The frequency dependence of specific alternating current (ac) conductivity was used to estimate the temperature-frequency intervals of charge transfer by long and short distances, respectively. With increasing the concentration of nanoparticles, specific ac conductivity increases. The concentration dependence of dielectric permittivity suggests that distribution of nanoparticles is homogeneous, and conducting channels are not formed. With increasing the concentration of silver nanoparticles, the glass transition temperature of the nanocomposites, described in terms of the strength/fragility concept, increases, whereas the strength parameter D decreases (i.e., "fragility" increases).