Polyion-complexed assemblies of diacetylenic carboxylic acid with triblock polyamine carrying a boronic acid-functionalized segment

Abstract

The polyion complex of 10,12-pentacosadiynoic acid 1 and a novel ABA-type triblock polyamine 2, containing phenylboronic acid groups as sugar-responsive sites, has been prepared. Monolayer properties of the complex 2/1 are examined by measuring surface pressure (pi;)-area (A) isotherms on water. The pi;-A curves are found to vary drastically by changing pH in the subphase, suggesting the conformational change of the copolymer segment of 2 containing phenylboronic acid groups and/or deformation of the polyion complex of 2/1. Polymerizations of the complex monolayer of 2/1 are carried out upon UV irradiation, resulting in successful production of polydiacetylene with a blue form under optimum conditions of pH, temperature, substrate, surface pressure and so on. When the polymerized 2/1 LB film deposited on a quartz plate is immersed in aqueous solutions of various diol compounds such as sugars and nucleosides, a remarkable spectral variation due to blue to red color phase change of the polydiacetylene matrices is observed, implying binding of the diol compounds to the phenylboronic acid moieties located at the LB film surface. The extent of the spectral variation of the LB film seems to be proportional to the binding ability for the diol compounds.