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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 51: Poster Session III-2

CPP 51.9: Poster

Dienstag, 17. März 2020, 14:00–16:00, P2/EG

Hydrodynamics and Response of PNIPAM Microgel Aqueous Solution Subjected to Acoustic Waves — •Amin Rahimzadeh and Regine von Klitzing — Physics department, Technical University of Darmstadt, Germany

The poly(N-isopropylacrylamide)(PNIPAM) stimuli-responsive microgels were the subject of studies so far where their reaction to changes in temperature in aqueous solutions has been systematically investigated. Microgels shrink in the solution above their volume phase transition temperature(VPTT) due to the breaking of hydrogen bonds between PNIPAM and the solvent. Acoustic waves, on the other hand, can transfer a certain amount of energy by penetrating into a liquid solution. Depending on the wave frequency and amplitude, flow patterns inside of the liquid affected by the propagating waves can result in microstreaming to atomization and micro drop ejection. We transfer acoustic waves into a sessile water droplet containing PNIPAM microgels to study their response by carefully tuning the ultrasonic power. Therefore, the amount of energy enough for breaking the hydrogen bonds-that is not high to deteriorate the polymer chains-is a crucial parameter in this context. The shrinking/swelling behavior, dynamic stiffness, as well as streaming pattern of microgels, are subjected to analyze in this work.