Characterization of microgels in ionic liquid

Abstract: Microgels are thermoresponsive nanoparticles whose size is dependent on temperature. The microgels were studied using both dynamic light scattering (DLS) and scanning electron microscopy (SEM) to better understand the nanoparticles dynamics. The first part of the study focused on developing a controlled preparation procedure which would generate reproducible SEM images utilizing ionic liquid, which is a low vapor pressure solvent. The ionic liquid was mixed with a dilute solution of microgels and dehydrated using nitrogen gas. This technique allowed a large volume of microgels to easily transition from their natural water solvent to a low vapor pressure ionic solvent. The second part of the study attempts to correlate the diffusion found from microgels in ionic liquid using scanning electron microscopy to the statistical average diffusion measured with dynamic light scattering. The microgels in ionic liquid observed with SEM exhibited a polydispersed system with sizes ranging between 120-300 nm. As expected, these sizes are smaller than what is observed for a water based microgel with DLS.