Structure and Dynamics of Biobased Polyester Nanocomposites.

The structure and the dynamics of two bio-based polyester polyols are investigated in the bulk and close to surfaces in polymer/layered silicate nanocomposites. The morphology of the neat polymers as well as the structure of the nanohybrids are investigated with X-ray diffraction and their thermal properties are studied by differential scanning calorimetry. One of the investigated polyesters is amorphous, whereas the second one is a semicrystalline polymer with intriguing thermal behavior. Hybrids have been synthesized over a broad range of compositions and intercalated structures are always obtained. The thermal transitions in the nanocomposites are observed only when the polymers are in excess outside the completely filled galleries. The glass transition, whenever it can be resolved, appears insensitive to the presence of the inorganic material, whereas the way the crystallization takes place depends on the composition of the nanohybrid. Dielectric relaxation spectroscopy was utilized to study the polymer dynamics. It revealed multiple relaxation processes for the neat polymers both below and above their glass transition temperatures, whereas in the nanocomposites, similarities and differences are observed depending on the specific mode of the dynamic process.