Electrochemical Study of Core-Shell Microgels

• Published in: Polymer bulletin (Berlin, Germany) Vol. 61; no. 3; pp. 373 - 381
• Main Author: Seo, Seong S.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.09.2008; Springer; Springer Nature B.V
• Subjects: Ammonia; Applied sciences; Aqueous solutions; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Complex Fluids and Microfluidics; Diffusion coefficient; Electrochemical analysis; Exact sciences and technology; Free radical polymerization; Free radicals; Microgels; Organic Chemistry; Organic polymers; Photon correlation spectroscopy; Physical Chemistry; Physicochemistry of polymers; Polymer Sciences; Properties and characterization; Ruthenium; Soft and Granular Matter; Solution and gel properties; Temperature effects; Diffusion Coefficient; Lower Critical Solution Temperature; Hydrodynamic Radius; Dynamic Light Scattering; Transport properties; Hydrodynamic radius; Temperature effect; pH effect; Experimental study; Metallocene; Acrylamide derivative polymer; Molecule scattering; Polyelectrolyte; Cyclic voltammetry; Aqueous medium; Acrylic acid polymer; Ruthenium Complexes; Microgel; Measurement method; Chronoamperometry; Diffusion coefficient
• ISSN: 0170-0839; 1436-2449
• DOI: 10.1007/s00289-008-0960-4

Core and core-shell microgels are synthesized by aqueous free radical precipitation polymerization and their solvent release effects characterized. Dynamic light scattering (DLS) reveals hydrodynamic radii (Rh) decrease sharply at lower critical solution temperature (LCST) of 32 o C. Electrochemical properties of microgels were also investigated using cyclic voltammetry (CV) and chronoamperometry (CA) with electroactive probes: Fc(MeOH) 2 , uncharged and Ru(NH 3 ) 6 Cl 3 , positively charged. By measuring the effect of temperature change on the diffusion coefficients, I estimated the electrostatic interactions in varying solutions: aqueous (without migrogels), 25% core microgel and 25 % core-shell microgel solution systems. The diffusion coefficient of uncharged ferrocenedimethanol Fc(MeOH) 2 was found to increase as temperature increases, in both core or core-shell solutions. Positive charged Ru(NH 3 ) 6 Cl 3 shows a different behavior in both 25% core and 25% core-shell systems. In aqueous solution, increasing temperature brings increased diffusion coefficients. With the addition of core and core-shell microgel solution systems, diffusion coefficients fall sharply above LCST. This suggests that there is some amount of electrostatic interactions between negatively charged core and core-shell microgels and positively charged Ru(NH 3 ) 6 Cl 3 .