US EPA

6566826 

Book/Book Chapter 

Approaches to the Design of Sustainable Permanent Hair Dyes 

Williams, TN 

2018 

ProQuest Dissertations Publishing 

Ann Arbor 

North Carolina State University 

11007240 

376 

English 

Interest in designing sustainable permanent hair dyes derives from the toxicological concerns associated with certain commercial dyes, in particular the moderate to strong/extreme skin sensitization potential of certain precursors used to develop the dyes. While work has been undertaken to help address toxicological concerns of hair dyes, alternatives having commercial success are based on the conventional permanent hair dye coloration process and still may pose health problems. The conventional process involves the oxidation of small and essentially colorless precursors (e.g., p-phenylenediamine and resorcinol) within the hair fiber that couple to build oligomeric indo dyes that are difficult to desorb. The resultant depth of shade achieved is superior that of other hair dyes and provides a high degree of gray coverage. In fact, these dyes dominate the commercial realm and stimulate the multibillion-dollar global hair dye market for the millions of consumers (men and women) who use them. Approaches to the design of sustainable (less toxic) permanent hair dyes lie at the heart of the present study. In Part 1 of this study, two types of keratin films (opaque and translucent) were characterized for their potential as screening tools for predicting the efficacy of potential hair dyes using the hair dye, C.I. Acid Orange 7. Translucent keratin films, which were found to be less porous than opaque films and more like hair in this regard, were deemed better tools for predicting the efficacy of potential hair dyes on hair. C.I. Acid Orange 7 was found to be uniformly distributed in both film types. However, a higher concentration of dye was detected in translucent films following the rinsing process. In Part 2 of this study, a cheminformatics clustering analysis of the 313 compounds in a Hair Dye Substance Database (HDSD) developed in this investigation, revealed some semipermanent hair dyes grouped among several hair dye precursors. This finding suggested that these dyes share similar properties with the precursors and may diffuse into hair fibers similarly. Two of the semipermanent dyes (C.I. Basic Orange 1 and 2) were used as model compounds to screen the digitized component of the Max Weaver Dye Library (MWDL, 2,196 total compounds) to identify analogous structures. Two similarity search analyses were performed to funnel the selection of dyes to 4 dyes having a phenylazopyrimidine substructure, a substructure not found among any of the compounds in the HDSD. One dye was predicted to be a human skin sensitizer, and two of the dyes displayed good affinity towards hair. Thus, the HDSD was an effective screening tool for identifying potential hair dyes. In Part 3 of this study, the synthesis and characterization of metallizable azo dyes revealed that the dyes could be dimerized as a post-treatment on keratin fibers and films. The best degree of dye uptake was seen for an arylazonaphthol dye. It exhibited no or moderate aquatic toxicity at concentrations tested and was found to be non-mutagenic in the Ames test. Although it was predicted to be a human skin sensitizer, this result requires experimental validation. The wash resistance of both unmetallized and metallized (Al3+ and Fe3+) forms of the dye at up to 10 wash cycles was better than observed for a commercial red permanent hair dye. Indeed, the wash resistance of metallized dye was best, indicating its potential as a permanent hair dye replacement. 

Chemistry; Polymer chemistry; Environmental science; (2018)