Effect of polymer molecular weight on Langmuir monolayers and the deposition of Langmuir-Blodgett films of poly(3-butylthiophene) and stearic acid

Poly(3-octylthiophene)/stearic Acid Langmuir and Langmuir-Blodgett films: Preparation and characterization

“…This is an indication that P3OT did not form a true monolayer, with the polymer forming aggregated and/or being coiled during the compression, in a way that only part of repeat units of main chain is in contact with water surface, due to its rigidity. For instance, the stacking forming bilayers for Langmuir monolayers of polymers has been reported 16,23 . Therefore, it was not possible to fabricate good quality LB films of neat P3OT.…”

“…Since polythiophenes exhibit low amphiphilicity, an amphiphilic long chain fatty acid (viz. Stearic Acid, SA) has been used to assist the formation of high quality polythiophene monolayer and multilayer LB films [14][15][16] .…”

Polymer monolayers and Langmuir–Blodgett films. Polythiophenes

“…The study of mixed monolayers of poly(3-butylthiophene) and stearic acid, 70 like yet another study 65 of the poly(3-octylthiophene) ± eicosanoic acid system, did not show a plateau on the compression isotherms for the polymers with molecular masses differing by an order of magnitude (2.5610 5 and 1.5610 4 ). For these systems, as for the majority of other mixtures of fatty acids with polythiophenes, the area per monomer unit in a monolayer increases with an increase in the polymer content in the mixture.…”

“…In both cases (as for the majority of monolayers of low-and high-molecular-mass compounds), the surface potential starts to increase at monolayer areas considerably exceeding those where the increase in the surface pressure starts. The transfer of mixed monolayers onto a glass surface by the vertical method was studied in detail; 70 it was found that the transfer ratio is close to unity and that the resulting LB films of the Y type have homogeneous structures.…”

“…60 Differences between the absorption spectra of LB films of individual polythiophenes 16 and 17 and their films obtained from solution were observed; 31 ± 33 however, no differences were found between similar spectra of LB films obtained from a mixture with stearic acid and that of a film obtained from a solution of pure poly(3-hexylthiophene). 60,69,70 The position of the p ± p*-transition maximum in the absorption spectra of LB films consisting of mixed monolayers of poly(3-alkylthiophenes) and cadmium eicosanoate depends on the length of the polymer alkyl chain. 66 For example, for LB films of poly(3-decylthiophene) and poly(3-undecylthiophene), the absorption maximum of a 1 : 3 polymer : salt mixture was observed at 520 and 515 nm, respectively, whereas in the case of a film obtained from solution, the absorption maxima were at 477 and 500 nm.…”