104 JOURNAL OF COSMETIC SCIENCE When hair is oxidised, it undergoes a significant physico-chemical modification of its surface state: disulfide and peptide linkages breakdown and some of the outer cuticles are removed. As displayed in picture 1, damaged hair surface is rough and not as smooth as virgin hair. As a result of oxidation, surface is much more hydrophilic than virgin hair: the angle of contact drops to approximately 30°. Zeta potential measurements show that oxidation of hair has modified its surface charge, shifting to a globally neutral charge. Finally, our red-dye testing show that the density of cationic sites on the surface of oxidised hair has significantly increased r:__�__::..,_;.,. __ ._ ____ compared to healthy hair which displays less adsorption of the anionic red-dye. l?k1Ja:Ll: damaged hair surface Deposition of Guar HM on virgin hair can be significantly increased in presence of electrolytes. A similar trend sums to be true for damaged hair as well, but surely at a much lower level. This finding emphasises how the surface properties of damaged hair influence the behaviour of polymer floes. -0.DOIO Depo..lon Df Guar HM f0,4'9') on Vlfffl'" and DAMAGED NI'° Figure I: Deposition of Guar HM (0,4%) on virgin and damaged hair as a function of salt Similarly to Guar HM, all conditioning polymers tested display a larger amount deposited on virgin hair than on damaged hair (see in figure 2). Interestingly, only polysaccharides of high charge density and PQ-74 present a positive result for damaaed hair. This probably is the indication that a minimum amount of cationic charges is necessary so that some remains on hair after the rinsing step. Deposition of dimethicone oil on virgin hair is achieved with all polymers tested but there are great differences in terms of efficiency. On that respect, it appears that high molecular weight cationic guar and PQ-74 are of greater interest compared to cellulose polymers and synthetic polymers (see in figure 3). 0,120 Poly ar dePMl9e" on VlftOI and DMAOED hair f]g;y[:j_l: Polymer (0,2%) deposition on virgin and damaged hair I eoo 'I r -------�------1� l �1-------- l - :zao I··��-I � lll/ ,l /lll E]gy,rf_l: Dimethicone deposition on virgin and damaged hair Similarly to the deposition of polymer on damaged hair, dimethicone deposition on this hydrophilic surface is much more difficult and no clear trend on the polymer chemistry can be extracted. From the data displayed above, one can first conclude that a good deposition polymer for virgin hair is not necessarily effective on d aged hair. Additionally, it appears that PQ-74 polymer deposits dimethicone better than others on damaged hair, while having a very good profile for virgin hair as well. Rderepces: [l]: US Patent No. 3,472,840 (1969) [2]: ED. Goddard, RB. Hannan, "Cationic polymer/ anionic surfactant interactions", J. Colloid and lnterf. Sci., SS, 73-79, ( J 976) [3]: J. Jachowicz, M. Berthiaume, M. Garcia, "The effect of amphiprotic nature of human hair keratin on the adsorption of high charge density cationic polyelectrolytes", Colloid & Polymer Sci., 263, 847-858, (1985) (4]: Karnath YK, Dansizer CJ, Weigmann HD, J. Soc. Cosmet. Chem., 28, 273-284, (1977)