Molecular dynamics
The structure-properties relationship in polymers, amorphous and semicrystalline, and in polymer nanocomposites (PNCs) is under extensive investigation over the last decades. The role of polymer chemistry, inter- and intra- chain interactions, the presence of nanofillers imposing attractive or repulsive interfacial interactions to the hosting polymer matrix and the presence of crystals of various morphologies, induce serious alternations on the materials performance. Except for the structural characteristics of the synthesized materials, extremely useful has been proved the understanding of effects imposed on the molecular mobility. The latter exhibits homogeneous characteristics within areas of a few nanometers, i.e. the range of static and dynamic grass transition, as well as within smaller areas, i.e. the range of more localized molecular motions (sub-nano). The presence of polymer crystals and/or nanometric inclusions (nanoparticles, NPs) introduce various direct and indirect effects on dynamics, for example either hindering (e.g. strong interactions) or favoring (increase in free volume, nanometric spatial confinement) polymer chains diffusion and cooperativity. Among these effects, the role of crystals and interfacial polymer (RAF) due to crystals and to filler/polymer interfaces [1, 2, 3] has been revealed, in accordance with findings from the literature.
Broad Dielectric Spectroscopy
The basic tool to experimentally assess molecular dynamics is the sophisticated technique of Broad Dielectric Spectroscopy (BDS), or else called Dielectric Relaxation Spectroscopy (DRS), which supplemented by the widely known differential scanning calorimetry (DSC, TMDSC) and other structural characterization techniques (FTIR, NMR, XRD, SEM, AFM, PLM/POM), is able to provide quite detailed insight directly on polymer dynamics and indirectly on the filler- and crystal- induced effects.
During the last years, our Lab in close collaboration with the Dielectrics Group of NTUA (http://dielectricsgroup.physics.ntua.gr/) has presented a significant number of experimental results on polymer dynamics in bulk, amorphous and in the presence of crystals, as well as in nanocomposites. Our results have been published in International peer reviewed journals , whereas our reports have received quite fast significant numbers of citations from groups worldwide.
Our main efforts have been dedicated on the macroscopic materials performance (mechanical performance [4, 5], thermal diffusion [6], electrical conductivity), which are of practical importance considering the envisaged applications in the everyday life, the industrial scale and the bio-medical scale.
