ИСТИНА

Analytical potential of polyurethane foam (PUF) functional groups has been systematically studied. Heterogeneous chemical reactions of terminal toluidine groups result in formation of intensely colored products. Those are diazotization with sodium nitrite, azo-coupling with 4-nitrophenyldiazonium tetrafluoroborate and diazotized aromatic amines, condensation with aromatic aldehydes and azo-coupling of diazotized PUF with different compounds. It has been shown that terminal toluidine groups have chemical properties similar to those of monomeric aromatic amines. The main factors influencing on chemosorption of the substances on PUF have been revealed. These are pH and composition of aqueous phase, phase contact time, structure of the PUF polymeric chain and concentrations of the reagents. The conditions of maximum yield of diazotized polyurethane, polymeric azo-compounds and Schiff bases have been determined. Using diffuse reflectance and IR spectroscopy, the new absorbance bands have been found and interpreted that proves the chemical modifying of PUF. Schemes of the chemosorption of different substances on PUF have been suggested. The area of application of PUFs as polymeric chromogenic reagents for diffuse reflectance spectroscopy and test-methods has been proved. The role of functional groups in such reagents is played by terminal toluidine groups or different groups of compounds covalently linked with PUF. It has been suggested to use office scanner, digital camera and computer data processing as an alternative approach to numerical evaluation of color intensity of the reaction products of unmodified as well as modified PUF. The examples showing the advantages of PUF as a polymeric chromogenic reagent have been given. It has been shown that there is an opportunity of its application for determination of nitrites, phenols, aromatic amines and aldehydes. The metrological characteristics of the methods and the results of samples analysis have been estimated.