Berlin 2024 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 24: Responsive and Adaptive Systems I

CPP 24.5: Talk

Wednesday, March 20, 2024, 10:45–11:00, H 0110

Dynamic Light Scattering for Characterization of PNIPAM Microgels Subjected to Ultrasound — Sebastian Stock, Leila Sahebmohammadi, Regine von Klitzing, and •Amin Rahimzadeh — Soft Matter at Interfaces, Technical University of Darmstadt, Darmstadt, Germany

Dynamic Light Scattering (DLS) is a widely employed technique for characterizing particles and molecules in solutions/dispersions, offering insights into their size, size distribution, and conformational changes. This study leverages DLS to explore the ultrasound-induced Volume Phase Transition (VPT) of poly(N-isopropylacrylamide) (PNIPAM) microgels. By innovatively integrating ultrasound with a conventional DLS system, we conducted experiments to characterize compact silica particles and microgels under ultrasound influence. Essential parameters, including particle size, frequency, and amplitude of particle vibration, were successfully extracted through analysis of the correlation function of the scattered light intensity. Notably, studies involving non-responsive silica particles demonstrated that ultrasound did not compromise size determination, establishing them as suitable reference systems. Our findings reveal the acousto-responsive nature of PNIPAM microgels, showcasing their ability to undergo VPT over the time of actuation. Microgels exposed to ultrasound exhibit comparable swelling/shrinking behavior to that induced by temperature, albeit with markedly accelerated kinetics. The outcomes of this investigation hold promise for diverse industrial and biomedical applications.

Keywords: PNIPAM microgels; dynamic light scattering; ultrasound