A Study of the Reaction Between Protein Monolayers and Wool-Reactive Dyes

Abstract

Monolayers of edestin, as a model for protein fibers, have been spread on water and on aqueous solutions of three wool-reactive dyes with and without the addition of urea. The film area, compressibility, and viscosity values were measured and interpreted. Surface tension measurements on aqueous solutions of the dyes agree qualitatively with the expected effects of their structural differences. The most surface-active dye, containing a single reactive group, penetrates the protein film rather slowly, slightly increasing the compressibility. On standing overnight, dye-protein reaction occurs, and the film becomes more rigid. A dye with two reactive groups causes a marked increase of rigidity of the film, and the dye-fiber reaction appears to be more rapid than the rate of dye penetration into the film. The third dye, with a single reactive group, is intermediate in effect on the film.

Urea expands the film and appears to open the protein structure without causing crosslinking. In presence of dye the more open protein structure appears to persist but on standing the film rigidity increases.