Detecting zeta potential of polydimethylsiloxane (PDMS) in electrolyte solutions with atomic force microscope

Zhijian Liu; Yongxin Song; Dongqing Li

doi:10.1016/j.jcis.2020.05.061

Detecting zeta potential of polydimethylsiloxane (PDMS) in electrolyte solutions with atomic force microscope

J Colloid Interface Sci. 2020 Oct 15:578:116-123. doi: 10.1016/j.jcis.2020.05.061. Epub 2020 Jun 2.

Authors

Zhijian Liu¹, Yongxin Song¹, Dongqing Li²

Affiliations

¹ Department of Marine Engineering, Dalian Maritime University, Dalian 116026, China.
² Department of Mechanical and Mechatronics Engineering, University of Waterloo, Waterloo, ON N2L 3G1, Canada. Electronic address: dongqing@uwaterloo.ca.

PMID: 32521351
DOI: 10.1016/j.jcis.2020.05.061

Abstract

Zeta potential of PDMS-liquid interface is an important parameter for generating electroosmotic flow in a PDMS microchannel. In this paper, the zeta potentials of a PDMS slab in contacting with electrolyte solutions were evaluated with an atomic force microscope (AFM). As a colloidal probe of the AFM approaches to the surface of a PDMS slab in an electrolyte solution, a force curve is obtained and used to calculate the zeta potential of the PDMS. The effects of the plasma treating time and the aging of the electrolyte solutions on the zeta potential of PDMS surfaces were examined. The experimental results show that the air plasma treating time does not change the zeta potential of PDMS appreciably. Furthermore, the decreased zeta potential of a plasma-treated PDMS in an electrolyte solution is due to liquid aging, not the PDMS itself. Such characteristics probed by AFM provide new understanding of the surface charges of PDMS in electrolyte solutions.

Keywords: AFM; Air plasma treatment; Liquid aging; PDMS; Zeta potential.