542 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS 2O BLEACHED HAIR 0 2 4 6 TIME(hours) Figure 1. Adsorption of Polymer JR-125 on bleached hair (0.1 per cent aqueous solution). Dotted line corresponds to data for adsorption of cetyl trimethylammonium bromide on bleached hair, from (3) Woodard (4) has provided data on the sorption kinetics of a quaternized polyethylene-imine polymer on virgin brown hair and on bleached hair, but only for times up to 60 min. Allowing for the higher concentration used (5 per cent), her data are similar to ours. Still another study, which should be noted, is the one of Finkelstein and Laden (5), who observed equilibrium times of several days for cationic surfactants on hair by a radio-tracer method. The relatively large amount of adsorption that is shown here calls for an ex- planation. Undamaged hair has a BET area of 0.04 sq m/g, a value about equal to the calculated geometrical area (6). Bleached hair has a SOlnewhat larger BET area, about 0.1 sq m/g (2). If one makes the admittedly simplistic •sumption that the Polymer JR molecules are stretched out fiat on this sur- face, a monolayer would account for only about 0.1 ./xg polymer per milligram of substrate. The level actually reached is much greater than this, so one must postulate considerable multilayer adsorption of some kind of penetration into the hair shaft. Although conclusive data do not yet exist, we favor the latter hypothesis. For one thing, adsorption of Polymer JR on glass surfaces (2) is only a small fraction of that on bleached hair (expressing both on an area basis). In the case of glass, equilibrium is apparently reached in a few rain-

ADSORPTION OF POLYMER JR BLEACHED HAIR 543 4O E 30 •' 20 c• 10 I I I I I I I 0 3 6 9 12 15 18 21 TIME(days) Figure 2. Adsorption of Polymer JR-125 on bleached hair (0.1 per cent aqueous solution) utes. The great length of time required to reach equilibrium for adsorption on hair suggests that a slow diffusion into the substrate is occurring. Indeed, such penetration was demonstrated for the cationic surfactants studied by Scott and coworkers (3). Because Polymer r JR is normally used in the presence of large amounts of surfactants, it was of interest to examine the effect of such materials on the ad- sorption of the polymer. An example is given in Fig. 3, which shows the effect of adding Tergitol 15-S-9, a nonionic surfactant. Some decrease in adsorption is noted at low concentration (1 per cent), but it requires a fairly large amount (10 per cent) before there is a significant effect. The decrease seen could be connected with modification of the hair by adsorption of surfactant, or by weak association of the polymer with the surfactant micelies. A more detailed picture is available from the simulated shampooing experi- ments, whose results are contained in Figs. 4 and 5. Widely varying results are seen for different systems. These concentrates, which have a high excess of surfactant over polymer, were all clear in appearance, as would be predicted from the results of Part I (Vol. 26, no. 9, Pp. 461-475, Sept. 1975). A summary of the precipitation patterns, which were observed for those surfactants not employed in Part I of this paper, is given below. Table I records the appear-