Multifunctional Graphene Hair Dye Chong Luo, Lingye Zhou, Kevin Chiou, Jiaxing Huang  Chem  Volume 4, Issue 4, Pages 784-794 (April 2018) DOI: 10.1016/j.chempr.2018.02.021 Copyright © 2018 Elsevier Inc. Terms and Conditions

Chem 2018 4, 784-794DOI: (10.1016/j.chempr.2018.02.021) Copyright © 2018 Elsevier Inc. Terms and Conditions

Figure 1 GO and r-GO (A) AFM image of GO sheets showing their lateral dimensions of several micrometers. The line scan (white line) indicates that the thickness of the sheets is around 1 nm. (B) Photo showing the colors of GO and r-GO dispersions and their coatings on glass slides. After reduction by ascorbic acid, the GO sheets in the brown dispersion (0.025 wt %, left vial) are converted to more hydrophobic r-GO and precipitate out of the water because of decreased dispersity (middle vial). Therefore, chitosan is added as a dispersing agent to form a uniform dispersion of r-GO in water (right vial). GO and r-GO/chitosan dispersions are stable and can easily form a uniform coating on glass slides (Figure 1B, bottom) by casting. (C) UV-vis spectra show that r-GO has much higher optical adsorption than GO in both the UV and visible ranges, consistent with their colors shown in (B). The inset shows a magnified view of the spectra between 400 and 700 nm. Chem 2018 4, 784-794DOI: (10.1016/j.chempr.2018.02.021) Copyright © 2018 Elsevier Inc. Terms and Conditions

Figure 2 Graphene Dyeing of Light-Colored Hair (A) Photo showing bundles of blonde hair before and after coating with r-GO/chitosan dye with increasing graphene concentrations, in comparison with another sample treated with a commercial permanent black hair dye. (B) SEM images showing the surfaces of uncoated and coated hair (0.25 wt %). (C) The lightness of uncoated and graphene-coated hairs, and those treated with the commercial permanent black hair dye, measured directly with a fiber-optic spectrometer. The error bars represent deviations of measured data from the corresponding means. (D) Representative stress-strain curves of a strand of hair before and after graphene coating, showing no apparent change in tensile properties. Chem 2018 4, 784-794DOI: (10.1016/j.chempr.2018.02.021) Copyright © 2018 Elsevier Inc. Terms and Conditions

Figure 3 Antistatic Property of Graphene-Coated Hair (A–C) Photos showing strands of (A) uncoated hair, (B) hair treated with a commercial black dye, and (C) graphene-coated hair before (top row) and after (bottom row) electrostatic charging. The strands are tied with an insulating cotton string on the top. Uncoated hairs and hairs treated with commercial dye cannot dissipate the electrostatic charges, and show a strong “flyaway” effect. The antistatic effect of the graphene coating (0.25 wt %) is evident. (D) The surface static voltage of the hair bundles decreased drastically with graphene coatings. The error bars represent deviations of measured data from the corresponding means. Chem 2018 4, 784-794DOI: (10.1016/j.chempr.2018.02.021) Copyright © 2018 Elsevier Inc. Terms and Conditions

Figure 4 Graphene Hair Dye Improves Thermal Conduction Snapshots taken with an IR camera show the thermal profiles of bundles of uncoated hair, graphene-coated hair (0.25 wt %), and hair treated with commercial black dye during (A) heating and (B) cooling. Graphene-coated hair heats up and cools down more rapidly as a result of better thermal conduction. Chem 2018 4, 784-794DOI: (10.1016/j.chempr.2018.02.021) Copyright © 2018 Elsevier Inc. Terms and Conditions

Figure 5 Durability of Graphene-Coated Hair against Washing (A and B) Photos showing bundles of (A) carbon black/chitosan-coated hair and (B) graphene-dyed hair (0.25 wt. %) before and after repeated shampoo washing. (C and D) The corresponding changes in (C) lightness and (D) surface static voltage. The results highlight the advantages of the 2D morphology of r-GO, whose barrier properties can better protect the composite against washing. Additional exhaustive washing tests showed that graphene-coated hair can sustain at least over 30 times of washing (C), which already approaches the performance requirement of commercial permanent hair dyes. The error bars represent deviations of measured data from the corresponding means. Chem 2018 4, 784-794DOI: (10.1016/j.chempr.2018.02.021) Copyright © 2018 Elsevier Inc. Terms and Conditions

Figure 6 Gradient Dyeing Using GO/Chitosan and Triggered by UV Irradiation Gradient coloring (A) and reduction in lightness (B) can be achieved by controlling the duration of UV irradiation on different segments of GO/chitosan-coated hair (0.25 wt. % of GO in the dye solution). The error bars represent deviations of measured data from the corresponding means. Chem 2018 4, 784-794DOI: (10.1016/j.chempr.2018.02.021) Copyright © 2018 Elsevier Inc. Terms and Conditions