Cholesterol-substituted 3,4-ethylenedioxythiophene (EDOT-MA-cholesterol) and Poly(3,4-ethylenedioxythiophene) (PEDOT-MA-cholesterol)

Yuhang Wu; Samadhan S. Nagane; Quintin Baugh; Chun-Yuan Lo; Shrirang S. Chhatre; Junghyun Lee; Peter Sitarik; Laure V. Kayser; David C. Martin

Giant (Aug 2023)

Cholesterol-substituted 3,4-ethylenedioxythiophene (EDOT-MA-cholesterol) and Poly(3,4-ethylenedioxythiophene) (PEDOT-MA-cholesterol)

Yuhang Wu,
Samadhan S. Nagane,
Quintin Baugh,
Chun-Yuan Lo,
Shrirang S. Chhatre,
Junghyun Lee,
Peter Sitarik,
Laure V. Kayser,
David C. Martin

Affiliations

Yuhang Wu: Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA
Samadhan S. Nagane: Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA
Quintin Baugh: Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA
Chun-Yuan Lo: Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware, 19716, USA.
Shrirang S. Chhatre: Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA
Junghyun Lee: Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA
Peter Sitarik: Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA
Laure V. Kayser: Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA; Department of Chemistry and Biochemistry, University of Delaware, Newark, Delaware, 19716, USA.
David C. Martin: Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA; Department of Biomedical Engineering, University of Delaware, Newark, Delaware, 19716, USA; Corresponding author at: Department of Materials Science and Engineering, University of Delaware, Newark, Delaware 19716, USA.

Journal volume & issue: Vol. 15
p. 100163

Abstract

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Cholesterol is a rigid, crystalline, non-polar natural substance that exists in animal blood and cell membranes. Some of its derivatives are known to form ordered liquid crystalline mesophases under suitable conditions. In this work, we carefully examined the influence of cholesterol substitution on the characteristics of 3,4-ethylenedioxythiophene (EDOT-MA-cholesterol) and its corresponding polymer poly(3,4-ethylenedioxythiophene) (PEDOT-MA-cholesterol) synthesized by both chemical and electrochemical polymerization. We found evidence for an ordered lamellar (smectic-like) structure in the EDOT-MA-cholesterol monomer by differential scanning calorimetry (DSC), polarized optical microscopy (POM), and X-ray diffraction techniques. The ordered phase was observed to form on cooling from the isotropic melt at about 80 °C. Due to the insulating and bulky cholesterol side group on the EDOT monomer, we found that there was a maximum charge density for electrodeposition at ∼ 0.155 C.cm−2. A series of electrodepositions were performed from 0 to 0.155 C.cm−2 for probing the change of the charge transport with more charges used for the electrodeposition. We found that the impedance increased in the high-frequency range (above 104 Hz) and decreased in the low-frequency range (below 102 Hz). Three equivalent circuit models were proposed for fitting impedance data at different charge densities for a better understanding of the film growth process. The suppressed cyclic voltammogram (CV) of PEDOT-MA-cholesterol showed that the charge storage capability was essentially eliminated in the thickest films. The limited doping of the films was corroborated by their diminished electrochromic behavior, polaron-dominating absorption in UV-vis, overoxidized S 2p X-ray Photoelectron Spectroscopy (XPS) signal of electrodeposited films, and proton Nuclear Magnetic Resonance (1H NMR) of chemically polymerized samples. Dense film morphologies were confirmed by scanning electron microscopy (SEM). Grazing incident X-ray diffraction (GIWAXS) indicated the disrupted stacking of conjugated chains, which correlated with the decreased conductivity of the PEDOT-MA-cholesterol films. The measurement of the electrical conductivity gave a value of around 3.30 × 10−6 S.cm−1 which is about six orders of magnitude lower than has been seen in PEDOT (∼3 S.cm-1).

Published in Giant

ISSN: 2666-5425 (Online)
Publisher: Elsevier
Country of publisher: United Kingdom
LCC subjects: Science: Science (General)
Website: https://www.journals.elsevier.com/giant

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