Berlin 2024 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 42: Gels, Polymer Networks and Elastomers III

CPP 42.4: Vortrag

Donnerstag, 21. März 2024, 15:45–16:00, H 0106

Restricted mobility of Ni nanorods in agarose hydrogels — •Nils Boussard and Andreas Tschöpe — Universität des Saarlandes, Experimentalphysik, Campus E2 6, 66123 Saarbrücken

The three-dimensionally linked polymer network in an agarose hydrogel has large pore sizes in a range comparable to the typical length of Ni nanorods (⟨ L ⟩ = 100−600nm). The liquid that fills the interstices of the network provides a medium for the movement of embedded particles and the aim of the present study was to investigate how the rotational motion of the magnetic nanorods in agarose hydrogels (0.3-1.0 wt.%) is constrained by the scaffold. To quantify the microstructure of the agarose hydrogels a correlation length ξ was obtained from spectrophotometric turbidity measurements. Due to a magnetic field during gel formation, the ferromagnetic nanorods could be aligned in parallel for the initial state and after switching off this field, the rods relaxed into a stationary orientation distribution. This state could be quantified via optical transmission measurements by an alignment parameter which correlated qualitatively with the ratio ⟨ L ⟩/ξ. For the combinations of nanorod length and agarose concentration of this study, the Ni nanorods showed the transition from nearly free mobility to fixation and a quantitative model was derived by adapting the Edwards tube model. The topological constraint on the rotational motion of the nanorods was approximated by a confining tube with a diameter proportional to the correlation length.

Keywords: Ni nanorods; agarose hydrogels; rotational motion; tube model