@article{KofodRisseStoyanovetal.2011, author = {Kofod, Guggi and Risse, Sebastian and Stoyanov, Hristiyan and McCarthy, Denis N. and Sokolov, Sergey and Kr{\"a}hnert, Ralph}, title = {Broad-spectrum enhancement of polymer composite dielectric constant at ultra low volume fractions of silica-supported copper nanoparticles}, series = {ACS nano}, volume = {5}, journal = {ACS nano}, number = {3}, publisher = {American Chemical Society}, address = {Washington}, issn = {1936-0851}, doi = {10.1021/nn103097q}, pages = {1623 -- 1629}, year = {2011}, abstract = {A new strategy for the synthesis of high permittivity polymer composites is demonstrated based on well-defined spatial distribution of ultralow amounts of conductive nanoparticles. The spatial distribution Was realized by immobilizing Cu nanoparticles within the pore system of Alia microspheres, preventing direct contact between individual Cu particles. Both Cu-loaded and unloaded silica microspheres were-then used as fillers in polymer composites prepared with thermoplastic SEBS rubber is the matrix. With a metallic Cu content of about 0.26 vol \% In the compoilte, a relative increase of 94\% In real permittivity was obtained. No Cu-induced relaxations were observed in the dielectric spectrum within the studied frequency range of 0.1 Hz to 1 MHz. When related to the amount of conductive nanoparticles, the obtained composites achieve the highest broad spectrum enhancement of permittivity ever reported for a polymer based composite.}, language = {en} } @misc{SchimkaLomadzeRabeetal.2017, author = {Schimka, Selina and Lomadze, Nino and Rabe, Maren and Kopyshev, Alexey and Lehmann, Maren and von Klitzing, Regine and Rumyantsev, Artem M. and Kramarenko, Elena Yu. and Santer, Svetlana}, title = {Photosensitive microgels containing azobenzene surfactants of different charges}, series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, journal = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe}, number = {461}, issn = {1866-8372}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-413528}, year = {2017}, abstract = {We report on light sensitive microgel particles that can change their volume reversibly in response to illumination with light of different wavelengths. To make the anionic microgels photosensitive we add surfactants with a positively charged polyamine head group and an azobenzene containing tail. Upon illumination, azobenzene undergoes a reversible photo-isomerization reaction from a trans- to a cis-state accompanied by a change in the hydrophobicity of the surfactant. Depending on the isomerization state, the surfactant molecules are either accommodated within the microgel (trans-state) resulting in its shrinkage or desorbed back into water (cis-isomer) letting the microgel swell. We have studied three surfactants differing in the number of amino groups, so that the number of charges of the surfactant head varies between 1 and 3. We have found experimentally and theoretically that the surfactant concentration needed for microgel compaction increases with decreasing number of charges of the head group. Utilization of polyamine azobenzene containing surfactants for the light triggered remote control of the microgel size opens up a possibility for applications of light responsive microgels as drug carriers in biology and medicine.}, language = {en} } @misc{TheteRojasNeumeyeretal.2013, author = {Thete, Aniket and Rojas, Oscar and Neumeyer, David and Koetz, Joachim and Dujardin, Erik}, title = {Ionic liquid-assisted morphosynthesis of gold nanorods using polyethyleneimine-capped seeds}, url = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-95196}, pages = {14294 -- 14298}, year = {2013}, abstract = {Seed-mediated gold nanorods with tunable lengths are prepared using new polyethyleneimine-capped gold nanoparticles synthesized in ionic liquid. The effect of polyethyleneimine and ionic liquid during nanorod growth is investigated and shows a marked effect on their final aspect ratio.}, language = {en} }