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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 35: Poster Session II

CPP 35.44: Poster

Wednesday, March 29, 2023, 11:00–13:00, P1

Effect of type of initiator and purification on the properties of thermo-responsive PNIPAM microgels — •Joanne Zimmer, Sebastian Stock, Souraj Mandal, Carina Schneider, Luca Mirau, and Regine von Klitzing — Soft Matter at Interfaces, Institute for Condensed Matter Physics, TU Darmstadt, Germany

Microgels (MG) are polymeric networks in the size range of micrometers boasting properties of both colloids and polymers. Depending on their composition MG can respond to external stimuli such as temperature or pH. An example of a thermo-responsive polymer is Poly(N-isopropylacrylamide) (PNIPAM). PNIPAM MG can be synthesized by surfactant-free precipitation polymerization comprising NIPAM monomers, the crosslinker N,N'-methylenebisacrylamide (BIS) and a radical initiator. Depending on the radical initiator, either negatively or positively charged MG are generated. The subject of this work is the evaluation of the MG charge on the thermo-responsive swelling behavior and elastic properties using Dynamic Light Scattering and Atomic Force Microscopy. In addition, the type of MG purification and its effect on the resulting MG properties is investigated. It was shown, that the presence of undesired low-molecular weight products strongly impacts the MG interfacial adsorption behavior what we wish to understand. In this regard, sufficient removal was only achieved if, apart from the standard purification via dialysis, subsequent centrifugation steps were carried-out. The MG bulk properties (hydrodynamic radius, Zeta-potential) remained unchanged before and after centrifugation.