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a well characterized material which makes it ideal for a dielectric and thermal comparative study. The effect that isothermal crystallization exerts on the behavior of relaxation processes α and δ by cooling the isotropic liquid below the nematic phase or through the process of cold crystallization by heating it from the supercooled state is explored by comparing the DRS and DSC. Furthermore, by employing the Avrami equation, we compare the ability to probe the crystallization with each technique.

Core-shell structured nanocomposites of polydimethylsiloxane with different polymerization degree (PMS100 and PMS50) and polymethylphenylsiloxane (PMPS4) immobilized onto fumed silica nanoparticles were studied by means of differential scanning calorimetry. The polysiloxanes were attached to the particles' surface using thermally stimulated binding and modification in the presence of depolymerization activator-dimethyl carbonate (DMC). Single-and multi-stage processes were applied in order to obtain a different architecture of polymeric layer on the silica nanoparticles surface. The effect of polysiloxane/DMC ratio on phase transitions of obtained polymeric layers was evaluated. The grafting of polydimethylsiloxane at the presence of chain scissor resulted in cross-linking of the attached polymeric layers. When using a multi-step modification with PMPS, a dense crosslinked layer was formed on the silica surface. Unlike the samples obtained by one-step modification with different polymer content, for which the amount of polymer attached to silica surface changes the parameters of the relaxation process in polymeric layer, for composites synthesized using multi-stage modification, a greater influence has the length of the oligomer introduced on first stage. The best results were achieved for composite with PMPS when using on the first stage of modification the PMPS/DMC mixture with low content of depolymerization agent (oligomers with long chain, respectively). A notable increase in the mobility of the polymeric layer was detected due to the formation of isotactic macromolecular chains.

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