From Single-Chain Nano-Particles to All-Polymer Nano-Composites

Single-Chain Nano-Particles (SCNPs) obtained by intra-molecular cross-linking of linear macromolecules (precursors) are emerging soft nano-objects showing unique and remarkable physicochemical, rheological, and sensing properties as a result of their locally collapsed structure and ultrasmall size. During last years, we have studied the properties of systems based on SCNPs, including dilute and crowded solutions, bulks and all-polymer nano-composites with SCNPs as fillers (see, e. g. [1]). Diverse techniques have been combined, including small angle scattering, quasielastic neutron scattering and coarse-gained molecular dynamics simulations. Here we present the results on the properties of SCNPs in solution and how they develop upon crowding their environment, with the all-polymer nano-composite as limit. In solution, SCNPs obtained through standard synthesis routes adopt sparse morphologies. Crowding induces compaction of the SCNPs and in the limit case of the nano-composite, the observed conformation of the SCNP resembles that of a crumpled globule. Furthermore, the impact of the presence of SCNPs on the dynamics of an entangled polymer matrix is addressed. In the dynamically asymmetric system investigated, we observe a slowing down of the Rouse-like dynamics as well as a pronounced increase of the explored volume of the (faster) matrix linear chains. The latter effect is attributed to the particular topology (internal compartmentation) of the slow SCNP filler component.

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