The dynamics of polymers on the molecular scale is of paramount importance for their macroscopic performance, e.g. mechanical stability, transport properties or even advanced functionalities like self-healing. This presentation will demonstrate how broadband dielectric spectroscopy can be used to unravel dynamical features in nano-structured materials and how the combination with complementary methods advances our understanding of the molecular characteristics. The first example will be a semi-crystalline star-polymer with a polyhedral oligomeric silesquioxane (POSS) molecule in its center [1]; due to the unusual architecture of this molecule, the partial crystallization constrains the conformation in the amorphous regions and results in an accelerated segmental relaxation – in stark contrast to the common slowing down in semi-crystalline polymers [2]. A detailed analysis of the dielectric spectra reveals three separate amorphous regions of different dynamics. Complimentary infrared spectroscopy measurements reveal a complex conformational evolution in the amorphous regions during the crystallization.<br/>In a second example, the impact of meso-phase separation in associating telechelc polymers will be shown. The hydrogen-bonding end groups in these polydimethylsiloxane based materials phase separate and, by that, establish conformations different from the unperturbed melt [3]. As a result, the segmental dynamics is constrained as reflected in broadened dielectric relaxation processes. Additionally, distinct features in complimentary shear modulus measurements can be linked to these conformational changes which indicate a strongly improved mechanical performance [4]. This demonstrates the relevance of these investigations also for the macroscopic properties of polymeric materials.<br/>

Polymer dynamics in nano-structured surroundings: Structure-property relations unraveled by broadband dielectric spectroscopy

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.