Dresden 2011 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 43: Nanoparticles and Composite Materials I

CPP 43.11: Vortrag

Donnerstag, 17. März 2011, 17:00–17:15, ZEU 222

(contribution withdrawn) Structure and dynamics of poly ethylene glycol grafted gold nanoparticles studied by neutron scattering — •Marco Maccarini — Institut Laue Langevin, Grenoble, France

Polymer-capped gold nanoparticles (AuNP) have many peculiar aspects like quantum size effects and single electron transitions. Their properties are highly dependent on their size and shape and upon spatial relationship of one particle to another. Coating nanoparticles with polymers tethered to their surface by means of specific ligands stabilizes them, and allows functionalization for specific applications in nanotechnologies, biology and biomedical studies. We studied the structure and the dynamics of a key class of polymer-capped AuNP, those coated with poly ethyleneglycol (PEG). A novel synthesis was developed by ligand exchange procedure, which ensure the production of NP with little excess of functionalizing ligand and high stability. The structure PEG AuNP were studied by combining small angle neutron scattering as a function of temperature, and of the length of the interfacial polymer chains. PEG Au NP functionalized with short (PEG400) and long (PEG2000) polymer reflected substantial differences in the structure of the polymer at the interface. The dynamics of PEG AuNP in the nanosecond timescale was also studied by neutron spin echo (NSE) spectroscopy. NSE experiments showed two dynamical processes, one related to the translational diffusion of the nanoparticles, and a faster due to internal motion of the polymer chains. For comparison, NSE experiments were performed on PEG2000 polymer in solutions. Analogies and differences between free and anchored polymer will be discussed.