A study of fluorescent-dye polyurethane ionomer

Abstract

The reaction of toluene diisocyanate with 4-hydroxycoumarin or 7-hydroxycoumarin or dicumarol and other additives to form the structure of fluorescent-dye polyurethane ionomer, which has been successfully synthesized at our laboratary, is demonstrated by Fourier transform infrared spectra. The fluorescence study of coumarins present in N,N-dimethyl acetamide indicates that these coumarins form aggregations and exhibit fluorescence at around 304 nm. The experimental results show that the surface tension of 4-hydroxycoumarin or 7-hydroxycoumarin in N,N-dimethylacetamide appears to decrease with increasing concentration of 4-hydroxycoumarin or 7-hydroxycoumarin. On the other hand, the surface tension of dicumarol in N,N-dimethylacetamide increases with increasing concentration of dicumarol, indicating that increased hydrophilic groups of dicumarol adsorbed at the surface of N,N-dimethylacetamide become even more ordered. For fluorescent-dye polyurethane ionomer in aqueous solution, the number average particle sizes are seen to increase with an increase of coumarin concentration. Since the intermolecular interaction between hydrophilic groups of fluorescent-dye polyurethane ionomer molecules themselves may become strong, therefore, the free volume of these ionomer molecules are considered to be increased significantly. This may be why the number average particle size becomes large. For self-cured films made by fluorescent-dye polyurethane ionomer, the tensile strength is seen to increase with increasing concentration of coumarin, as a result of increased crosslinking resulting from increased hydrophilic groups of coumarins attached to the backbone of the ionomer molecules. The elongation of self-cured film made by dicumarol-based polyurethane iomomer, on the other hand, decreases with increasing concentration of dicumarol. Copyright © 2000 John Wiley & Sons, Ltd.