PEDOT:PSS nano-particles in aqueous media: A comparative experimental and molecular dynamics study of particle size, morphology and z-potential

Karishma Jain; Aleksandar Y Mehandzhiyski; Igor Zozoulenko; Lars Wågberg

doi:10.1016/j.jcis.2020.09.070

PEDOT:PSS nano-particles in aqueous media: A comparative experimental and molecular dynamics study of particle size, morphology and z-potential

J Colloid Interface Sci. 2021 Feb 15:584:57-66. doi: 10.1016/j.jcis.2020.09.070. Epub 2020 Sep 24.

Authors

Karishma Jain¹, Aleksandar Y Mehandzhiyski², Igor Zozoulenko³, Lars Wågberg⁴

Affiliations

¹ Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 56, SE-100 44 Stockholm, Sweden.
² Laboratory of Organic Electronics, Department of Science and Technology (ITN), Campus Norrköping, Linköping University, 60174 Norrköping, Sweden.
³ Laboratory of Organic Electronics, Department of Science and Technology (ITN), Campus Norrköping, Linköping University, 60174 Norrköping, Sweden; Wallenberg Wood Science Center, Linköping University, SE-60174 Norrköping, Sweden. Electronic address: igor.zozoulenko@liu.se.
⁴ Department of Fibre and Polymer Technology, KTH Royal Institute of Technology, Teknikringen 56, SE-100 44 Stockholm, Sweden; Wallenberg Wood Science Center, KTH Royal Institute of Technology, Teknikringen 56, SE-100 44 Stockholm, Sweden. Electronic address: wagberg@kth.se.

PMID: 33059231
DOI: 10.1016/j.jcis.2020.09.070

Abstract

Pedot: PSS is the most widely used conducting polymer in organic and printed electronics.

Pedot: PSS films have been extensively studied to understand the morphology, ionic and electronic conductivity of the polymer. However, the polymer dispersion, which is used to cast or spin coat the films, is not well characterized and not well understood theoretically. Here, we study in detail the particle morphology, size, charge density and zeta potential (z-potential) by coarse-grained MD simulations and dynamic light scattering (DLS) measurements, for different pH levels and ionic strengths. The PEDOT:PSS particles were found to be 12 nm-19 nm in diameter and had a z-potential of -30 mV to -50 mV when pH was changed from 1.7 to 9, at an added NaCl concentration of 1 mM, as measured by DLS. These values changed significantly with changing pH and ionic strength of the solution. The charge density of PEDOT:PSS particles was also found to be dependent on pH and ionic strength. Besides, the distribution of different ions (PSS^-, PEDOT⁺, Na⁺, Cl^-) present in the solution is simulated to understand the particle morphology and molecular origin of z-potential in PEDOT:PSS dispersion. The trend in change of particle size, charge density and z- potential with changing pH and ionic strength are in good agreement between the simulations and experiments. Our results show that the molecular model developed in this work represents very well the PEDOT:PSS nano-particles in aqueous dispersion. With this study, we hope to provide new insight and an in-depth understanding of the morphology and z-potential evolution in PEDOT:PSS dispersion.

Keywords: Charge density; Dynamic light scattering; Molecular dynamics simulations; PEDOT:PSS; Particle morphology; Zeta potential.