Impedance spectroscopy characterization of relaxation mechanisms in gold–chitosan nanocomposites
Alexandra Neagu, Lavinia Curecheriu, Mirela Airimioaei, Ana Cazacu, Adrian Cernescu , Liliana Mitoseriu
Composites: Part B 71 (2015) 210–217 (2014)
Au–Chi nanocomposites with different AuNPs additions were investigated. The dispersion of AuNPs in
polymer matrix was observed using s-SNOM analysis. The dielectric properties as a function of temperature
show two relaxation processes: (1) a primary a-relaxation process, at low temperatures; (2) a second
low frequency relaxation at temperatures between 70 C and 150 C identified as the r-relaxation
often associated with short range ion mobility. In nanocomposite films, the r-relaxation process overcomes
the a-relaxation process so that the glass transition is no longer detected. The dielectric nonlinear
properties (tunability) shown an increase of dipolar moment with AuNPs additions and this results are in
good correlation with matrix modification in FTIR investigation.