Regensburg 2013 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 36: Poster: (Hydro)gels and Elastomers
CPP 36.2: Poster
Mittwoch, 13. März 2013, 16:30–18:30, Poster C
Poly(N-isopropylacrylamide) chains adsorbed on silica nanoparticles: A dielectric study of the phase transition of interfacial pNIPAM — •Marieke Füllbrandt1,2, Sarah T. Turner1, Regine von Klitzing1, and Andreas Schönhals2 — 1Stranski-Laboratorium für Physikalische und Theoretische Chemie, Technische Universität Berlin, Strasse des 17. Juni 124, D-10623 Berlin — 2BAM Bundesanstalt für Materialforschung und -prüfung, Unter den Eichen 87, D-12205 Berlin
Poly(N-isopropylacrylamide)(pNIPAM) is adsorbed on silica nanoparticles. In bulk phase linear pNIPAM shows a lower critical solution temperature (LCST) at about 32°C. In general the physical properties of constrained polymers differ from those of the bulk phase. Adsorbed pNIPAM on surfaces can have interesting applications in functionalized interfaces with thermosensitive properties. Such applications require fundamental knowledge of the transition behaviour and mobility of adsorbed pNIPAM chains.
Dielectric Relaxation Spectroscopy (DRS) is applied in a frequency range of 10^-1 to 10^6 Hz. By using charges as probes the phase transition of pNIPAM can be monitored by both the temperature dependence of the DC conductivity and the frequency dependence of the complex conductivity spectra [1]. The formation of a Si/pNIPAM core/shell particle where charges are trapped/ blocked at the interface evokes a Maxwell/Wagner/Sillars polarization. For structural information DLS measurements and TEM images are added. [1] M. Füllbrandt, R. von Klitzing and A. Schönhals, Soft Matter, 2012, 8, 12116-12123.