A 2-DIMENSIONAL NETWORK OF PHENOL-FORMALDEHYDE MONOLAYERS BY THE LANGMUIR-BLODGETT TECHNIQUE

A monolayer network film of a phenolic resin was produced through the Langmuir-Blodgett (LB) technique. Amphiphilic phenols, o-, m- and p-he xadecoxyphenol (o-, m- and p-HP), were synthesized by the reactions of catechol, resorcinol, and hydroquinone, respectively, with 1-iodohexa decane. Monolayers of the HPs were spread on aqueous subphases with di fferent pHs and on aqueous 1% formaldehyde subphase. The surface press ure-area isotherms revealed characteristic monolayer behaviors accordi ng to the structural isomers at the air-water interface. Spontaneous i ncrease of the surface pressure by the reaction of the phenol moiety w ith formaldehyde at the air-water interface was found on the aqueous f ormaldehyde subphase. The p-HP monolayer was transferred onto calcium fluoride substrate as Y-type and the molecular structure was determine d by the Fourier transform infrared spectroscopy (FTIR). Acid and foll owing heat treatments were applied for the enhancement of network form ation. The network film showed resistance toward organic solvents. The mechanical stability of the network film was indirectly evaluated by the scanning electron microscopy (SEM) observation of the LB film morp hology covered over the porous substrate and less than eight layers we re enough to cover the pores of 0.1 mu m diameter. (C) 1998 Elsevier S cience S.A. All rights reserved.