Polymerization and Surface Behavior of Alkyl-Substituted Aniline Surfactants at the Air−Aqueous Interface:  A Kinetic Study

Abstract

The surface behavior of 2-, 3-, and 4-pentadecylaniline (3a, 3b, and 3c, respectively) was studied at the air−aqueous interface of an acidic subphase. Surface dipole moments (μn) were calculated from the surface potentials (ΔV) of 3a−c and were related to the orientation of the anilinium ion at the interface. Further, 3a and 3b were polymerized in a Langmuir film, and analysis of the absorption spectra showed that the resulting polymers were in different oxidative states upon completion of the polymerization. A method that monitors the change in the mean molecular area (A) of the surfactant at a constant applied surface pressure and predicts the concentrations of monomer and polymer and/or oligomer at the interface in order to determine the formation rate (R p) of poly(alkylaniline) is presented. The R p values of 3a and 3b are expressed in terms of the concentrations of the monomer and polymer at the interface. It was determined that the R p of 3a was dependent on the applied surface pressure while 3b showed little dependence on surface pressure. Differences in R p can be explained by the conformation of the anilinium group and the steric hindrance of the alkyl group at the interface. A characteristic “autoacceleration effect” was observed for both 3a and 3b but was more significant in the case of 3a.

Langmuir Film Polymerization of 1,22-Bis(2-aminophenyl)docosane: A Two-Dimensional Cross-linked Polyalkylaniline

“…This communication presents the Langmuir film polymerization of a dipolar monomer, 1,22-bis(2-aminophenyl)docosane (BAD), which forms a 2-dimensional network polymer of polyalkylaniline. The surface behavior of BAD is presented and compared with that of the monopolar surfactant, 2-pentadecylaniline (PDA), which is routinely polymerized in Langmuir films. − …”

“…1 H NMR studies of this coupling reaction suggest that this self-metathesis reaction occurs selectively at the terminal olefin and not at the olefin next to the aromatic ring. PDA was synthesized by a route previously reported 1 …”

Poly(N‐octadecylaniline) Synthesized at the Air‐Water Interface: Aligned Nanofibers and Gold Nanocomposite Assembly via the Langmuir‐Blodgett Technique

“…A more targeted approach to the synthesis at the air‐water interface would involve polymerization carried out in the Langmuir film under surface pressure control. Penta and hexadecyl anilines with the alkyl chains on the benzene ring have been investigated in this context . Electrochemical polymerization of aniline has been carried out in a Langmuir trough in presence of exfoliated graphene oxide, to yield polyaniline with preferential orientation .…”

“…Penta and hexadecyl anilines with the alkyl chains on the benzene ring have been investigated in this context. [26][27][28] Electrochemical polymerization of aniline has been carried out in a Langmuir trough in presence of exfoliated graphene oxide, to yield polyaniline with preferential orientation. [29] We have explored earlier, the polymerization of N-octadecylaniline (NOA) in Langmuir films to form poly(N-octadecylaniline) (PNOA), focusing on the impact of polyelectrolyte templating.…”

Example of an organic reaction in a Langmuir film: Reduction of an amphiphilic ketone by NaBH4

“…Chemically initiated polymerizations of oriented monomers can be performed by just adding a catalyst or reagent in the subphase. Pyrrole monomers [1,2], derivatives of aniline [3][4][5][6][7][8], or vinyl monomers [9] have been polymerized in this way. In most of these studies, the reactions were followed by recording variations in the area per molecule at constant pressure or changes in surface pressure at constant area per molecule.…”