600 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table I Sorption of 5% PEI on Virgin Hair Type of PEI Time (rain) PEI Sorption (%) 600 tool wt 2 5 60 60,000 tool wt 2 5 6O 60,000 tool wt 2 PEI and 5 ethylene oxide 60 _ 05 06 1 2 08 09 1 2 1 0 1 2 1 6 The levels of PEI sorbed were all high, indicating that PEI is very sub- stantive to virgin hair'. The sorption by damaged hair was also studied. The virgin hair was da•naged by twice bleaching with 20 vohnne hydrogen peroxide for a total of 5 hours. Bleaching affects the sorption of higher molecular weight PEI 600 (60,000 mol wt) greater than the low molecular weight PEI 6 (600 tool wt). After one hour, 3.4% PEI 600 and 1.5% PEI 6 was sorbed by the bleached hair. The bleached hair sotbed approximately 3 times more PEI 600 than virgin hair, whereas only ¬ times more PEI fi was sorbed (Table II). The effect of pH on the sorption of PEI was determined. In this series of tests the virgin hair was immersed in 5% PEI solutions which had been adjusted to specific pH values. The rate of sorption was then determined as in the initial experiment. Sorption is slightly greater at pH 7 than pH 10 or pH 2, increasing by approximately ¬ (Table III). No study of pH effect on bleached hair was conducted. The concentration of PEI used in treating the hair was also varied to determine its effect on sorption. Virgin hair was immersed in 1% solu- tions of PEI 6 and PEI 600. Reducing the concentration of the PEI reduces the axnount of sorp- tion. An 80% reduction in concentration reduced the amount sotbed by 50%. After one hour, 0.6% PEI is sotbed on virgin hair from a 1% •,,()lution of PEI 6 or PEI 600 (Table IV). The rate .of desorption ot• PEI from hair was investigated in the sec- ond experiment. Hair samples were saturated in a 5% PEI solution for 24 hours. The hair was then removed from the c(mtact solution, rinsed

AZIRIDINE CHEMISTRY AND COSMETICS Table II Sorption of 5% PEI on Bleached Hair 601 PEI Type Hair 5 Min (%) 60 Min (%) 600 mol wt Bleached 0.8 1.5 Virgin 0.6 1.2 60,000 tool wt Bleached 2.6 3.4 Virgin 0.9 1.2 Table III pH Effect on Sorption of 5% PEI PEI Sorption (%) Type of PEI Time (min) pH 10 pH 7 pH 2 600 tool wt 5 0.6 0.8 0.5 60 1.2 1.7 1.4 60,000 tool wt 5 0.9 1.2 0.85 60 1.2 1.5 1.2 Table IV Sorption of 1% rs. 5% PEI on Virgin Hair PEI Sorption (%) Type of PEI Time (rain) 5% PEI 1% PEI 600 tool wt 5 0.6 0.3 60 1.2 0.6 60,000 lnol wt 5 0.9 0.35 60 1.2 0.6 4 times in distilled H20 for one minute, and rinsed in 5% PEI (un- tagged) solutions for times ranging froxn 5 min to 24 hours, and the rinse solutions were subjected to counting. The hair was counted after the 24-hour rinse. The counting was done in the same manner as in the sorption experiment mentioned previously. In view of the fast diffusion rate of PEI into/onto the hair, it is inter- esting to note the relatively slow desorption rate of PEI. After rinsing 24 hours, 32.5% of the PEI 600 has been removed from the hair or 0.8% PEI 600 still remains on the hair. As previously mentioned, a higher per cent of PEI 600E sorbs on hair than PEI 600, likewise a higher rate of desorption takes place with PEI 600E. Again, this looks like the differ- ence in the molecular weights of the two PEI's. The low molecular weight PEI 6 desorbs much faster than the higher molecular PEI 600.