Monolayer Studies of the Mechanism of Disperse Dyeing*

Abstract

The Langmuir film balance and the Davies surface‐film viscous traction apparatus have been used with films of cellulose triacetate alone and in presence of two different disperse dyes; these were C.I. Disperse Red 13, an azo dye having both proton‐donating and proton‐accepting groups in its molecule, and C.I. Disperse Yellow 13 (methoxybenzanthrone), which has only proton‐accepting groups. The results show that a 1:1 complex is formed between either dye molecule and a hexa‐acetylcellobiose unit of the cellulose triacetate molecule, and possibly also a complex with an aggregate of the yellow dye. This indicates a face‐to‐face association of the dye molecules (which are planar) with cellulose acetate. The association is probably a hydrogen‐bonding interaction.