Thin Films of a New Polar Substituted Polypyrrole

Abstract

We have investigated the properties of thin films of a substituted polypyrrole synthesized via the chemical oxidation of a chloroform solution of 5-acetamido-4,5,6,7-tetrahydro-2H-benzo[c]pyrrole. Repeated compressions of Langmuir films prepared by spreading a dilute chloroform/dimethyl sulfoxide solution of the polymer at an air−water interface have established their long-term stability as floating monolayers. Hysteresis experiments and surface potential measurements have indicated that while the stiff condensed layer changes its structure upon the first compression, the size and distribution of floating domains remain invariant under subsequent cycles of compression and decompression. An infrared spectroscopic investigation was carried out for KBr mixed pellets of the material and for Langmuir−Blodgett (LB) films obtained by depositing six monolayers of the polymer on ZnSe crystals. The presence of a broad bipolaron band both in the transmission and in the attenuated total reflection (ATR) spectra indicates that in its pristine form the polymer was already slightly doped, a hypothesis confirmed by preliminary two-probe measurements. To better understand the nature of the organization of the deposited films we performed a linear dichroism analysis of the polarized ATR spectra and found evidence that the polymeric chains are transferred in a helical manner along the surface of the substrate.

Thermodynamic characterization of the prevailing molecular interactions in mixed floating monolayers of phospholipids and usnic acid

“…(Through a preliminary quantum chemical analysis we have been able to identify the regions of the UA molecule most likely to interact with the hydrophobic aliphatic chains.) More detailed information about the relative orientation of the components in the mixed film could be obtained, for instance, by a linear dichroism analysis of the polarized attenuated total reflection infrared spectra of solid films [23].…”

Pyrrole derivatives for electrochemical coating of metallic medical devices

“…This shift was due to the steric effect that the substituents induce in the electrochemical polymerization. Because the polypyrroles are α‐α′ coupled,1 the large bulky groups, which are covalently attached to the pyrrole in the N‐position, are likely to introduce a barrier toward the formation of a linear polymer.…”

“…Among the several types of conducting polymers under this investigation, polyaniline and polypyrrole derivatives stand out for combining significant environmental stability and high electrical conductivity. Polymers of these families of compounds are commonly synthesized via the oxidative coupling of the respective monomers 1. Polypyrrole coatings are also used as a corrosion‐protecting layer over iron2, 3 and other metals 4…”

Soluble fluorescent polymeric nanoparticles based on pyrrole derivatives: synthesis, characterization and their structure dependent sensing properties

“…1 PPy is one of the most promising conjugated polymers for its biocompatibility, good thermal and environmental stability, high electrical conductivity and ease of synthesis. A first approach toward increasing the solubility of PPy is to substitute pyrrole monomer at either carbon 18,19 or nitrogen 20,21 atoms and then polymerize the new derivatives into PPy. Despite these advantages, the main drawback of PPy is its poor solubility in most common solvents which restricts its processability and makes it difficult to study optical and morphological properties of this polymer in solution phase.…”

“…Over the years, several strategies have been employed by scientists to deal with this solubility problem. A first approach toward increasing the solubility of PPy is to substitute pyrrole monomers at either carbon 18,19 or nitrogen 20,21 atoms and then to polymerize the new derivatives into PPy. By using this method soluble PPys with various properties have been obtained depending on type of substituent.…”