ABSTRACT WILLIAMS, TOVA N. Approaches to the Design of Sustainable Permanent Hair Dyes (Under the direction of Harold S. Freeman). 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. © Copyright 2018 Tova N. Williams All Rights Reserved Approaches to the Design of Sustainable Permanent Hair Dyes by Tova N. Williams A dissertation submitted to the Graduate Faculty of North Carolina State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy Fiber and Polymer Science Raleigh, North Carolina 2018 APPROVED BY: _______________________________ _______________________________ Dr. Harold S. Freeman Dr. Denis Fourches Committee Chair ________________________________ _______________________________ Dr. Samuel M. Hudson Dr. Roger L. McMullen External Member _______________________________ Dr. Melissa A. Pasquinelli DEDICATION I would like to dedicate my dissertation to my heavenly Father….We did it! ii BIOGRAPHY Tova N. Williams is a native of Jacksonville, North Carolina. She earned her Bachelor of Science degree in Polymer and Color Chemistry from North Carolina State University in spring 2014. A dedicated member of the Wolfpack, she continued her educational pursuits at NC State in the fall of 2014 by commencing her Doctor of Philosophy Studies in Fiber and Polymer Science with a Chemistry minor. Passionate to make exposures to hair dyes safer for consumers like her mother and herself, hair stylists, and manufacturers, she focused on research dedicated to the “Approaches to the Design of Sustainable Permanent Hair Dyes” under the direction of Dr. Harold S. Freeman. While pursuing her research, she was funded by the National Institutes of Health (NIH) on a competitive Initiative for Maximizing Student Diversity (IMSD) Assistantship from 2014 - 2015. In 2015, she was awarded a prestigious National Science Foundation (NSF) Graduate Research Fellowship Program. She was also awarded an American Chemical Society (ACS) Ciba Giegy Travel Award, enabling her to present her research at the 20th Annual Green Chemistry & Engineering Conference in Portland, Oregon pertaining to “Exploring keratin films as a substrate in the design of sustainable hair colorants.” For two consecutive years (2014 – 2016), she was awarded a Diversity Enhancement Grant through the NC State Graduate School for her demonstrated commitment to diversity in STEM. During her academic career, Tova presented her research at seven conferences, including the 18th International Symposium on Toxicity Assessment held in Limeria, São Paulo, Brazil. Her research has been published in the American Chemical Society Sustainable Chemistry and Engineering journal and was featured on the April 2018 Volume 6, Number 4 cover. Beyond her research studies, Tova is passionate about cultivating the next generation of scientists through K-12 STEM outreach and serving as a mentor to women interested in STEM careers. iii ACKNOWLEDGMENTS I am a firm advocate that “it takes a village to raise a child.” Thus, the completion of this dissertation would not have been possible without the support of many individuals and groups. In lieu of providing an exhaustive list, only a few will be specially acknowledged here. Some other individuals will be specially acknowledged in other sections of the dissertation. I would first like to acknowledge my heavenly Father, Whom this dissertation is also dedicated. Not only did You call me to become “Dr. Williams,” You were my #1 cheerleader throughout this journey and my refuge and strength, always ready to help in times of trouble. Secondly, I would like to thank my committee members whose expertise was invaluable for the fruition of my research and my cultivation as a Ph.D. Scholar: Drs. Harold S. Freeman (Chair), Denis Fourches, Samuel M. Hudson, Roger L. McMullen, and Melissa A. Pasquinelli. I am because of you all! Also, I would like to acknowledge my #2 cheerleader, my mother, Calamity (Jean) Williams. We both did not know what to expect when I started this journey, but you remained with me from the beginning to the end through tears of resilience and joy. Thank you for the love you displayed throughout this process. I am also appreciative of the support of my other family members: my father, David Williams, and my sisters, Tonka Williams and Treva Rives. Keith Greats, my love, though you started this journey with me when I was well into it, you also did not know what you were getting into, but you were very caring and always willing to help. I really appreciated that, and I was grateful for your emotional and technical support. I would also like to acknowledge my mentors: Dr. Harold S. Freeman and Toni Harris Thorpe (aka “Mama Thorpe”), and Drs. Melissa A. Pasquinelli and Nacole B. King. Dr. Freeman and Mama Thorpe, now I see the “other side” and am grateful! Thank you for not only iv letting God use you to encourage me to become “Dr. Williams” but also for your outstanding emotional support, guidance, and patience throughout this journey. Dr. Pasquinelli, thank you also for your exceptional emotional support and helping me pursue and achieve my dreams! Thank you also for letting me grow and develop as a member in your laboratory for some time. I really valued the provision and guidance I received. Dr. King, I appreciated your encouragement, guidance, and the many laughs we shared throughout my journey. I am so glad we crossed paths, and you are truly an inspiration to me! I am also very appreciative of the NC State Initiative for Maximizing Student Diversity (IMSD program), in particular of Drs. Erin Banks and Felysha Jenkins, for not letting me "actually quit" on several occasions and nurturing me into the Ph.D. Scholar I am today. I am indebted to the Dr. Harold S. Freeman Research Group. Thank you especially Drs. Malgorzata Szymczyk, Tuane Santos, and Yi Ding for your motivating words, helping me troubleshoot experiments gone wrong, assisting me with instrumentation and interpreting results, feedback on presentations, the list goes on and on. I am also especially appreciative of the undergraduate women who assisted me with my studies: Victoria (Tori) Rizk (Fall 2015 – Spring 2016), Keila (Kaylie) Powell (Spring 2016), Jadavia Hunt (Fall 2016), Gabriel Murphy (Fall 2016), and Tu Vo (Fall 2016). I enjoyed watching you dive deep into your projects, and believe it or not, learned a lot from each of you. I am very grateful I had the opportunity to train and mentor you. I would also like to acknowledge my collaborators: Dr. Antony J. Williams of the National Center for Computational Toxicology, United States Environmental Protection Agency (Research Triangle Park, NC), Dr.