Abstract

Polymerization and characterization of the monolayers composed of a boronic acid-carrying diacetylenic compound, m-(10,12-pentacosadiynamide)phenylboronic acid (DA-PBA), have been performed at the air–water interface and on solid substrates. m-(10,12-Pentacosadiynamide)anisole (DA-An), which has a methoxy group in place of the boronic acid group, has also been prepared and used for comparison. DA-PBA formed a stable monolayer on water. Photopolymerization of the monolayer proceeded successfully on water at both 5 and 20 °C and gave a highly conjugated blue polymer with absorption maxima at 600 and 645 nm. The DA-PBA LB film transferred from the surface monolayer onto a quartz plate also provides such a blue polymer upon UV irradiation. This polymerized DA-PBA LB film was found to display completely reversible thermochromism between 20 and 70 °C, and the boronic acid groups located at the surface of the LB film did not interact with poly(vinyl alcohol) at all. Therefore, the spontaneous dehydration among boronic acid groups was supposed to occur, accompanied by polymerization of the diacetylene moiety. The formation of borate glass was supported by FT-IR and XPS spectroscopies.