Engineering the mobility in hydrogel films

• Applicant: Kaloian Koynov, Ph.D.
• Subject Area: Experimental and Theoretical Physics of Polymers
• Term: from 2010 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 175622145

Stimuli-responsive hydrophilic gels have attracted considerable interest since they exhibit abrupt volume changes and phase separation in response to external stimuli. In particular, the thermoresponsive poly-N-isopropylacrylamide (PNIPAAm) hydrogel is one of the most promising candidates for several applications. Their realization requires a thorough understanding of structure and dynamics of hydrogels often in the form of thin films. In the previous project, we have established a synthesis protocol (aiming at DNA sensoring) (Langmuir 23, 2231 (2007)) and developed a new light scattering technique (Soft Matter 4, 1443 (2008)) (possessing spatiotemporal resolution) and successfully applied Fluorescence Correlation Spectroscopy (FCS) (J.Phys. Chem.C. 111,13205 (2007)) (enabling single tracer detection) to investigate ancored hydrogels with micrometer thickness. These achievements create the appropriate platform for a thorough study of the penetration and mobility of various tracers (different size and shape) inside the PNIPAAm hydrogel layers with different crosslinking density and temperatures covering the swollen and collapsed regime. This study will include penetrants with different size/shape and interactions with the hydrogel matrix. A complementary structural characterization of the hydrogels is also planned by SANS (P. Mueller-Buschbaum and C. Papadakis in TUM) whereas access to the density profiles will be enabled by surface plasmon resonanse and waveguide mode techniques.

• DFG Programme: Priority Programmes
• Subproject of: SPP 1259: Intelligent Hydrogels
• Participating Person: Professor Dr. Georg Fytas