Berlin 2008 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 13: Colloidal and Nanoparticles
CPP 13.3: Vortrag
Dienstag, 26. Februar 2008, 15:30–15:45, C 264
Temperature, pH, and ionic strength induced changes of the swelling behavior of PNIPAM-Poly(Allylacetic-Acid) copolymer microgels. — •Thomas Hellweg1 and Matthias Karg2 — 1Universität Bayreuth, Physikalische Chemie I, Universitaetsstr. 30, 95447 Bayreuth, Germany — 2TU Berlin, Institut f. Chemie, Stranski-Lab. f. Theoretische und Physikalische Chemie, Strasse des 17.Juni 124, 10623 Berlin, Germany
The volume transition of colloidal microgels made of N-isopropylacrylamide (NIPAM) can be affected by copolymerization. Therefore, a series of poly(N-isopropylacrylamide-co-allylacetic acid) copolymers with different contents of allylacetic acid (AAA) was synthesized by means of emulsion polymerization. The thermo-responsive behavior of these particles was studied using dynamic light scattering (DLS). Further characterization was done employing transmission electron microscopy (TEM) and zeta potential measurements. The measured zeta potentials provide information about the relative surface charge. Since these copolymers are much more sensitive to external stimuli such as pH and ionic strength than their pure PNIPAM counterparts the volume phase transition was investigated at two different pH values and various salt concentrations. At pH 10 for some of the copolymer microgels a significant shift of the volume phase transition temperature towards higher temperatures is found. For higher AAA contents a change in pH from 8 to 10 can induce a change in radius of 100 nm making the particles interesting as pH controlled actuators.