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.

602 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS I PERCENT PEI 6ø I I % REMOVED PEI 6 REMOVED PEI 600E PEI 600 0 100 200 300 400 500 600 700 800 OOO 1000 DESORPTION TIME - MINUTES Figure 6. Desorption of PEI from hair into 5% solution of PEI (untagged) I 10% SHAMPOO • • o•1 I I I I I I o 5o '•oo 15o 200 250 :•oo •o RINSE TIME -- MINUTES Figure 7. De•rption of PEI 600 into 10• shamp• •lufion 4OO Initially PEI 6 desorbs 4 times faster than the PEI 600 and after 24 hours approximately 0.3% PEI 6 remains on the hair (Fig. 6). One of the main applications for PEI appears to be in the treatment of hair. The permanence of the treatment is very dependent upon its resistance to removal by highly anionic shampoos. Desorption was checked on PEI 600-treated virgin hair using a 10% solution as a rinse. The ani•onic shampoo removes more PEI 600 than the water PEI 600 rinse. But after 360 min of rinsing with the shampoo, 0.8% PEI 600 still remains on the hair. (Fig. 7). CONCLUSION It has been clearly shown that PEI is very substantive to hair, that the degree is directly related to hair damage, and that desorption is very slow. These properties are all highly desirable in hair care products. It is im- portant to realize that even though a low molecular weight PEI, a high molecular weight PEI, or a derivative of PEI all are substantive to hair,