Oxidative Coupling Polymerization in a Langmuir Monolayer of Octadecyl 3,5-Diaminobenzoate

Abstract

In a Langmuir monolayer of the surface active monomer octadecyl 3,5-diaminobenzoate (ODDB), stabilized at a surface pressure of 10 mN/m and a temperature of 23.7°C at the air-water interface, oxidative coupling polymerization occurs when copper(II) chloride was added or already was present in the subphase. Even in the absence of the catalyst this reaction takes place. Deposition of the polymerized monolayer onto glass, zinc sulfide, or gold substrates, using the vertical dipping method, gave transfer ratios between 0 and 0.4 on the downstroke and 1 on the upstroke. The multilayer films on zinc sulfide and gold substrates were characterized by means of Fourier transform IR spectroscopy, and multilayer films on quartz were characterized by means of UV/vis spectroscopy. Collected monolayers were characterized by means of size exclusion chromatography and again Fourier transform IR and UV/vis spectroscopy. During the stabilization of the monolayer without addition of copper(II) chloride to the subphase, the area per molecule decreased very slowly. Addition of copper(II) chloride enhanced this effect. The reduction of the area per molecule is probably caused by the polymerization itself accompanied by a reorientation of the molecules in the monolayer at the air-water interface. After stabilization the area per molecule was found to be about 27 Å 2 and electron micrographs showed the formation of a smooth monolayer. From this it has been concluded that a closely packed monolayer was formed. Fourier transform IR and UV/vis spectra of polymerized multilayer materials are analogous to the spectra of the azo polymer of ODDB prepared in bulk solution. Size exclusion chromatography revealed that the molecular weight and the molecular weight distribution of the coupling product with and without copper(II) chloride in the subphase were the same. The average molecular weight was somewhat lower than the high-molecular-weight part of the corresponding material prepared in bulk solution.

Cross-linking of polybutadiene at the air/water interface: Toward an easy access to two-dimensional polymeric materials

“…This strategy was subsequently used by other research groups to polymerize small molecules in Langmuir monolayers [2][3][4][5][6][7][8][9][10][11]. Among them, alkylalkoxysilanes [7,12] have been widely used, and our group has for instance investigated some of the fundamental aspects of the air/water interfacial cross-linking of octadecyltrimethoxysilane (OTMS) and octadecyltriethoxysilane (OTES) under acidic conditions [7].…”

Interfacial polymerisation of anilinium at Langmuir monolayers

“…While the properties of such films have been intensively studied and several classes of reactions have been examined, 1 there have been relatively few reports on polymerisation in this environment. 3,4 Moreover, in all studies that we are aware of the monomer was covalently attached to the amphiphile, affecting its mobility and limiting the polymerisation to a monolayer.…”

“…Following these background studies in bulk solution, polymerisation at the air-water interface was carried out under a variety of conditions, below the threshold identified above. To follow the interfacial reaction we monitored the change of surface area under a constant surface pressure, as a function of time 3,4 with simultaneous Brewster Angle Microscopy (BAM) measurements. We observed negligible change in the molecular area at a range of constant surface pressures (0.5-20 mN m 21 ).…”

Polymer−Surfactant Layered Heterostructures by Electropolymerization of Phenosafranine in Langmuir−Blodgett Films

“…12,13 Alternatively, direct use of surface-active monomer is also possible. The surface-active monomer can be polymerized either at the air-water interface 14,15 or after deposition of LB films of the monomer on solid substrate. 7,16 As a strategy, if the monomer is arranged in the form of a wellordered LB film and then polymerized, an ordered twodimensional polymer can be obtained as against threedimensional amorphous polymer films obtained with electropolymerization from solution.…”