Diacetylenic monolayers containing a boronic acid moiety form a chemicallyand thermally stable poly(diacetylene) film on water

Polymerization and characterization of the monolayers composed of a boronic acid-carrying diacetylenic compound, m-(10,12-pentacosadiynamide)phenylbor onic acid (DA-PBA), have been performed at the air-water interface and on s olid substrates. m-(10,12-Pentacosadiynamide)anisole (DA-An), which has a m ethoxy group in place of the boronic acid group, has also been prepared and used for comparison. DA-PBA formed a stable monolayer on water. Photopolym erization of the monolayer proceeded successfully on water at both 5 and 20 degreesC and gave a highly conjugated blue polymer with absorption maxima at 600 and 645 nm. The DA-PBA LB film transferred from the surface monolaye r onto a quartz plate also provides such a blue polymer upon UV irradiation . This polymerized DA-PBA LB film was found to display completely reversibl e thermochromism between 20 and 70 degreesC, and the boronic acid groups lo cated at the surface of the LB film did not interact with poly(vinyl alcoho l) at all. Therefore, the spontaneous dehydration among boronic acid groups was supposed to occur, accompanied by polymerization of the diacetylene mo iety. The formation of borate glass was supported by FT-IR and XPS spectros copies.