Estimating the thickness of hydrated ultrathin poly(o-phenylenediamine) film by atomic force microscopy

Abstract

A novel method to measure ultrathin poly(o-phenylenediamine) (PPD) film electropolymerized on gold electrode in liquid was developed.It is based on the force versus distance curve (force curve) of atomic force microscopy (AFM). When 1-0.25 m/s was chosen as the rising rate of the scanner, and 50% of the confidence interval (CI) as the qualifying threshold value, the thickness of the hydrated polymer film could be calculated. This result was compared with one obtained from an AFM image. A step-like electrode fabricated by a photolithographic process was used. The height difference of the electrode before and after the PPD coating was imaged in liquid, and then the real thickness, 19.6 ± 5.2 nm, was obtained. The sample was also measured by estimating the transition range of the force curve of hydrated PPD film, and the thickness of the hydrated PPD film was determined to be 19.3 ± 8.2 nm. However, the results calculated by integrating the electropolymerized charge for the oxidation process of o-phenylenediamine (o-PD) was only one-third as large as it was when using the two previously described methods. This indicated that the structure of hydrated PPD film might have been swollen.

Multifunctional 3D nanoarchitectures for energy storage and conversion

“…Although deposited under conditions where they are electrically insulating, ultrathin polyarylamine coatings are readily converted to their protonated, redox-active forms when exposed to acidic electrolytes. The self-limiting polymerization of aniline-related monomers of interest for energy storage such as o-phenylenediamine [84][85][86][87][88][89][90] and o-aminophenol 72,78,80,81 has been reported, but important aspects of structure, growth mechanism, and electrochemical properties have not yet been fully addressed, even at 2D interfaces. Reactions in confined volumes, which is a nanoarchitectural given, can be expected to differ from those reactions operative at planar electrodes, both with respect to mechanism of nucleation and growth of the film and even the thickness of a passivating film in 3D vs. 2D.…”

Highly selective and stable microdisc biosensors for l-glutamate monitoring

“…Effect of PPD polymerization potential on the selectivity of Pt D /PPD-BSA The structure of PPD films and their mechanisms of formation are known to be complex, and have been studied in some detail by many authors [34][35][36][37][38][39][40][41][42]. The properties of PPD have been suggested to depend mainly on the conditions of the polymerization, such as pH, electrolyte composition, temperature and the applied potential.…”

Localized Detection of d‐Serine by using an Enzymatic Amperometric Biosensor and Scanning Electrochemical Microscopy

“…The number of electropolymerization cycles was increased such that 5, 10, 30, and 50 cycles resulted in a PPD film thickness of 84±5, 101±11, 132±17, and 141±7 nm ( n =10), respectively, as determined by AFM (Figure S1). Note that the thickness of the PPD film has been shown to vary under hydrated or dehydrated conditions, such that the operational thickness within the biosensor may be slightly larger due to swelling …”