Spectroscopic, Microscopic, and Surface Analysis of Alkanethiol- and Fluoroalkanethiol-Modified Conducting Polymer Thin Films

Abstract

Electrochemically grown films of polyaniline, polypyrrole, polythiophene, and poly(ethylenedioxythiophene) were treated with alkane-and fluoroalkanethiols for 1-24 h. The resulting films showed surface energies and polarities similar to glass slides coated with monolayers of the corresponding alkyl-and fluoroalkylsilanes. Treatment of the polyaniline, polypyrrole, and, to a lesser extent, poly-(ethylenedioxythiophene) films resulted in covalent bonding of the thiol to the polymer backbone as evidenced by X-ray photoelectron, energy-dispersive X-ray, and electronic spectroscopies. Polypyrrole and poly(ethylenedioxythiophene) films showed reduced electroactivity upon treatment, while the derivatized polyaniline could be returned to a conducting state. Polythiophene primarily oxidized the thiols to soluble products, leaving the polymer backbone unaffected.

Electrochemistry of Poly(3,4‐alkylenedioxythiophene) Derivatives

“…Berman and Hanks studied the electropolymerization and surface morphology of PEDOT and compared this with polyaniline, polythiophene, and polypyrrole. [156] They concluded that the PEDOT films proved to be the most problematic to study. As can be seen by the SEM micrograph in Figure 22, PEDOT/BF 4 grew both as a film and a fine precipitate (CH 2 Cl 2 as solvent).…”

“…[155] Although the resolution is somewhat poor, the authors observe similar phenomena (stripes, dots, or cloud clusters) to that found by Hanks and Bergman. [156] Figure 23 shows the SEM images of PEDOT/ PF 6 surfaces as a function of the oxidation potential. When comparing XRD results with SEM measurements, the authors observe different stages in the growth process, which result in different morphologies and crystallinity, ranging from an amorphous and dense packed film (ca.…”

Surface modification of polypyrrole/biopolymer composites for controlled protein and cellular adhesion

“…We have shown that the surface properties of ICPs, either with conventional dopants or in composites with carbohydrate biopolymers, can be modified by exposure to thiols (Bergman & Hanks 2000, Hanks et al 2005, Molino et al 2012b. The thiols may be in solution or in the gas phase and the extent of reaction depends upon exposure time.…”

Impedance study of thiolated polyaniline

“…The overall effect of thiolation is the reduction of the PANI backbone where quinoid rings are reduced to benzenoid rings while the thiol is bound covalently to the benzene ring [14][15][16][17][18]. We have shown that the same phenomenon of reduction of PANI takes place also with emeraldine salt where no quinoid units are present (Blomquist et al, manuscript submitted for publication).…”

“…The overall effect of thiolation leads to a reduced PANI backbone [13][14][15][16][17][18]. Aromatic rings will become three-substituted and, depending on the nature of the substituent, steric hindrance will be increased [19].…”