Surface characterization of human hair using tapping mode atomic force microscopy and measurement of conditioner thickness distribution
(a) Schematic structure of human hair (Ref. 3); (b) schematic of the outermost surface of hair showing 18-MEA location (Ref. 6).
(a) Schematic diagram of atomic force microscope (AFM); (b) schematic of contact mode and tapping mode AFM operations. The tip remains in full contact throughout the scan in contact mode, while in the tapping mode the tip only lightly taps the sample surface as it scans.
(a) Typical force calibration plot for a commercial conditioner treated hair. Snap-in distance, , is a measure of film thickness on the sample surface; (b) schematic diagrams of the AFM tip, conditioner, and hair surface at different tip sample separations, as labeled.
Surface height maps and corresponding power spectrum plots for virgin and damaged treated samples. A image at the scale edge as well as a image away from the scale edge are included. PSDFs show that tapping mode measures more high frequency data than does contact mode, especially for the treated sample.
(a) surface height images away from the scale edge for all samples, measured in both contact mode and tapping mode, and their corresponding PSDFs; (b) tapping mode surface height images of a size at the scale edge. The arrows indicate the locations of the visible conditioner deposits.
(a) Typical force calibration plot (extend portion only) showing the difference between the damaged samples with varying levels of conditioner treatment; (b) typical force calibration plot (extend portion only) showing the difference for damaged treated sample at the scale edge base and away from the scale edge. The attractive forces are believed to be unaffected by the thickness of the conditioner layer and the tip easily passes through the conditioner, lending to the similar values of force for both samples.
(a) Film thickness and adhesive force maps for all samples. The maps are for areas of size, away from the scale edges. The histograms of thickness distribution are also shown; (b) the surface height maps and corresponding film thickness maps for damaged samples of varying conditioner treatment. The thickness maps clearly show that the conditioner deposits heavily at the scale edge base.
Adhesive force maps over a area away from the scale edges taken with a coated, hydrophobic tip.
(a) Comparison of the coefficient of friction taken with both coated and uncoated tips; (b) comparison of the adhesive force taken with both coated and uncoated tips. The uncoated tip adhesive force data are taken from LaTorre and Bhushan (2005).
Contact angle and surface energy of relevant materials associated with nanotribological characterization of hair.
High frequency power for surface height maps away from scale edges.
Mean conditioner thickness and adhesive force values.
Coefficient of friction and adhesion measured with both coated and uncoated tips.
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