Dyeing in Two Dimensions. A Review of the Use of the Monolayer Method in the Study of Dye‐Fibre Reactions

Abstract

Brief reference to the origins of studies of monolayer films on water is followed by descriptions of two of the principal methods of examining their properties: the relation between film area and pressure, and the surface viscosity. Films can be produced either from actual fibre‐forming polymers, e.g. cellulose, cellulose triacetate (CTA) or models, e.g. certain proteins to represent wool, and their reactions with dyes studied. All effects of the morphology of the fibres, especially porosity, can thus be eliminated, and the actual fibre‐dye forces revealed. Three general types of film behaviour have been identified in the above type of study: Monionic dyes penetrate the film, while their ionic group remains in the water. The film is thus expanded, but becomes weaker and more compressible. Examples include monosulphonated dyes with proteins and mono‐ionic basic dyes with cellulose. Dyes with planar molecules and two or more widely spaced sulphonate groups, with cellulose or protein films, as well as disperse dyes with CTA, orientate beneath the film, with their molecules parallel with the polymer chains in the film. Direct dyes with cellulose react in this way, but the bond to the cellulose is weak, and the film viscosity is not increased. Disperse dyes form a strong bond with the CTA film, by polar forces, and increase the film viscosity. Reactive dyes or bifunctional dyes with certain strongly‐bonding groups, e.g. ‐OH, in the molecule, expand the film and greatly increase its viscosity and in certain cases form crosslinks with the polymer chains, thus strengthening the film. The application of the Gibbs adsorption equation to some of the above types of reaction is discussed.

The roles of polymer relaxation phenomena, aqueous dye solubility and the physical properties of water in the mechanism of adsorption of a disperse dye on poly(ethylene terephthalate) fibres: Part 4 further aspects related to polymer relaxation phenomena

“…Despite the many differences between cotton, PA 66 and PET fibres, it is widely assumed that the mechanism of disperse dye adsorption described earlier in the case of PET fibres 2 applies to each of these three types of textile fibre (eg, [4][5][6][7][8] ). This all-encompassing mechanistic assumption therefore tacitly presupposes that the manner by which disperse dyes interact with PET, cotton and PA 66 substrates is identical, which implies that the particular physico-chemical characteristics responsible for disperse dye-fibre substantivity and the forces of interaction that govern both the diffusivity of the dyes and their adsorption within the different types of fibre, are also identical.…”

The roles of elevated temperature and carriers in the dyeing of polyester fibres using disperse dyes: Part 3 model of dye adsorption based on dye solubility

“…Whilst some workers 9,95 consider that the dyes are monomolecularly distributed in both the dyebath and PET fibre phases, or that monomolecular dye may be present only within the fibre phase, 96 other workers suggest the dyes are adsorbed in monomolecular form but subsequently aggregate 97 or undergo some change in physical state as a result of dye‐fibre interaction 98 . Evidence 99–101 suggests that whilst a proportion of adsorbed dye is monodisperse, with the remainder likely taking the form of small aggregates, the presence of aggregates of disperse dyes within PET materials having been secured 102–104 …”

The roles of elevated temperature and carriers in the dyeing of polyester fibres using disperse dyes: Part 2. Analysis of conventional models of dye adsorption

“…34 three quite different types of substrate, which, in turn, could be considered to imply that a similar mechanism of dye adsorption may well operate. In this particular context, it is widely assumed that the adsorption of disperse dyes to all types of common textile fibres occurs according to the same mechanism (e.g., 5,21,33,34,45 ), which therefore presumes that the manner by which disperse dyes interact with a diverse variety of textile fibres, such as silk, cotton, PAN, PET, wool, silk, etc., is identical. This particular, all-inclusive mechanistic approach therefore presupposes that disperse dye/silk, disperse dye/cotton, disperse dye/PAN, disperse dye/PET, etc., substantivity is identical in nature: more importantly, it also assumes that the same intermolecular forces must operate between the hydrophobic dye molecules and the various types of fibrous macromolecule that display such markedly different physical and chemical properties.…”

“…As mentioned, it is widely assumed that the same mechanism applies to the adsorption of disperse dyes on all types of common textile fibre. 5,21,33,34,45 In turn, this implies that the various forces of interaction responsible for dye-fibre substantivity are likely identical, irrespective of the nature and type of textile fibre involved. It seems apposite to consider the plausibility or otherwise of this all-inclusive mechanistic approach.…”