Temperature Dependence of Electrophoretic Mobility and Hydrodynamic Radius of Microgels of Poly(N-isopropylacrylamide)

Yasuyuki Maki; Kentaro Sugawara; Daisuke Nagai

doi:10.3390/gels4020037

Temperature Dependence of Electrophoretic Mobility and Hydrodynamic Radius of Microgels of Poly(N-isopropylacrylamide)

Gels. 2018 Apr 20;4(2):37. doi: 10.3390/gels4020037.

Authors

Yasuyuki Maki¹, Kentaro Sugawara², Daisuke Nagai³

Affiliations

¹ Department of Chemistry, Graduate School of Science, Kyushu University, Fukuoka 819-0395, Japan. maki@chem.kyushu-univ.jp.
² Division of Molecular Science, Faculty of Science and Technology, Gunma University, Kiryu 376-8515, Japan. t14801041@gunma-u.ac.jp.
³ Division of Molecular Science, Faculty of Science and Technology, Gunma University, Kiryu 376-8515, Japan. daisukenagai@gunma-u.ac.jp.

Abstract

Electrostatic interactions in charged microgels, which are dominated by the microgel net charge, play a crucial role in colloidal stabilization and loading of small, charged molecules. In this study, the temperature dependences of electrophoretic mobility μ and hydrodynamic radius R_h were measured for a slightly ionized poly(N-isopropylacrylamide) (PNIPA) microgel in a dilute suspension. A decrease in R_h was observed in the temperature range between 30 °C and 35 °C, corresponding to the lower critical solution temperature of PNIPA, and an increase in |μ| was observed in a higher temperature range between 34 °C and 37 °C. The analysis based on electrophoresis theory for spherical polyelectrolytes indicated that the net charge of the microgel decreased as the microgel was deswollen.

Keywords: electrophoresis; light scattering; microgel.

Grants and funding

15K20906/JSPS KAKENHI (Grants-in-Aid for Scientific Research)