Nanometer-scale ionic reservoir based on ion-responsive hydrogels

Sergey V. Kazakov; Marian Kaholek; Kalle Levon

doi:10.1117/12.475202

11 July 2002 Nanometer-scale ionic reservoir based on ion-responsive hydrogels

Sergey V. Kazakov, Marian Kaholek, Kalle Levon

Proceedings Volume 4695, Smart Structures and Materials 2002: Electroactive Polymer Actuators and Devices (EAPAD); (2002) https://doi.org/10.1117/12.475202
Event: SPIE's 9th Annual International Symposium on Smart Structures and Materials, 2002, San Diego, California, United States

Abstract

The applicability of the concept of ionic reservoir for the description of hydrogel behavior was demonstrated by potentiometric titration of poly(N-isopropylacrylamide-co-1- vinylimidazole) hydrogel suspension. Four different regions of pH-changes of the microgel suspensions were identified on the titration curve in comparison with pure water. Particularly, at 10.5>pH>6.5 a hydrogel accumulates or releases H⁺ and Cl^- ions without significant swelling/deswelling whereas at 6.5>pH>4 the storage of the ions occurs both due to their binding with ionizable groups on polymer network and due to strong swelling. The mechanical response of hydrogel (swelling/deswelling) is assumed to be a faster process than the electrochemical response (equilibration of ion concentrations interior and exterior to the hydrogel). The size of hydrogel spheres should be diminished to fasten an ionic reservoir response of the hydrogel. A novel protocol for preparation of polymer hydrogel spherical particles on a nanometer scale (nanogels) has been developed. Temperature- and pH-sensitive nanogels were detected and characterized by the dynamic light scattering technique and atomic force microscopy. Ptoentiometric titration of the obtained nanogels shows that the decrease in the ionic reservoir size gains the efficiency and, presumably, the rate of the electrochemical response. These findings indicate the necessity of time-resolved pH-measurements of the hydrogel suspensions for the characterization of the rate of the solute diffusion through the gel/water surface.

Citation Download Citation

Sergey V. Kazakov, Marian Kaholek, and Kalle Levon "Nanometer-scale ionic reservoir based on ion-responsive hydrogels", Proc. SPIE 4695, Smart Structures and Materials 2002: Electroactive Polymer Actuators and Devices (EAPAD), (11 July 2002); https://doi.org/10.1117/12.475202

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