468 100 90 80 70 ?ft. 60 C "'C 50 C 40 � 30 20 10 0 JOURNAL OF COSMETIC SCIENCE Stereomicroscopy Results of Mending Efficacy primary Splits, complete+partial mending '21 before combing '//�".I--- - --- - - - - 67.6 � after combing 50.4 with complex(11110-61B) No complex( 11203-152A) Figure 13. Total percent mending of formula with complex vs control. ing scores after multiple wash cycles. Measurements taken before and after treatment after one cycle are approximately the same as the previous data and show again the reproducibility of the data. The implications of these conclusions related to consumer performance include that the product can be claimed that it will not have the negative effects of build up with continued use and that product directions should include adding the product to the hair after every shampoo in order to obtain the desired effect. There are few commercially available products on the market that claim split end mending. The one found was tested as a benchmark for performance to the formula with the polyelectrolyte complex. Although the commercial product was able to mend split ends initially after treatment, the mends failed after post combing. Total percent mend- ing is considerably lower after combing for the commercial product vs. the formula with the polyelectrolyte complex (Figure 16A). Durability index of the commercial product is much lower especially for primary split ends (Figure 16B). The mechanism responsible for temporarily mending split ends in the commercial product is probably through a lowering of the surface energy of the fibers after treatment. The damaged parts of the fibers are then attracted through weak hydrophobic bonds. Ingredients responsible for this are the blend of silicones in the product such as cyclopentasiloxane, dimethicone, alkyl modified dimethicone, dimethiconol, and amodimethicone. Other ingredients having the same effect are the cationic surfactants and organic oils refer to methods section for ingredient labeling. This hydrophobic mechanism, although it provides a high degree of mending, fails to provide durability to the mend as exemplified in the

� ra en C: C: 2006 TRI/PRINCETON CONFERENCE Mending Efficacy vs. Charge Ratio of Polyquaternium-28 to PVM/MA Copolymer 100 r-----�---'--------------- 90 A 80 70 60 50 40 30 20 10 0- 0.4 0.6 0.8 rrending % before combing durability 1.2 1.4 1.6 1.8 2 Charge Ratio ■ mending % after combing - - Poly. (durability) 469 0.90 0.80 0.70 0.60 � 0.50 :s 0.40 0.30 C 0.20 0.10 0.00 , Poly. (mending % after combing) ---Poly. (mending% before combing) Figure 14. Mending efficacy vs charge ratio of cationic to anionic polymer. A) Total % Mending of Primary Splits B) Durability Index f'l!t�i:il i!�U� j Cycle 1 Cycle 2 Cycle 5 o.oo , l'.i! Total% Mending Before Combing liil Total % Mending After Combing ISi Wash Col Durability Index Combing B Durability Index Wash Figure 15. Cumulative effects and mending durability to washing over the course of five cycles. (A) Total percent mending of primary splits. (B) Durability index. post combing durability test. The hydrophobic bonding of the components of the split fiber is not strong enough to withstand the stress of the combing process. In our screening experiments for the polyelectrolyte complex it was found that there were many compounds that could mend split ends prior to stressing the tress to test the durability of the mend. It was the ability of the complex to durably mend the split ends after this post combing process that provides this semi-permanent mending ability. Based on the surface characteristics of damaged hair as well as the structure and chemical interactions of the polyelectrolyte complex with hair, a theory was proposed on the possible mechanism of this semi-permanent split end mending. PROPOSED THEORY OF SPLIT END MENDING Hydrophilic character of damaged hair. Human hair consists of a central core called the