Manufacturers are challenged to create benefit-driven shampoos and conditioners, with the focus shifting to true innovation, and not a basic cleansing product. Hair conditioning ingredients are used for hair manageability. Hair manageability includes taking care of the various material properties of hair. These properties include:
• Frictional properties, which include combing, feel, body, hair breakage.
• Electrostatic properties, such as triboelectric charging or flyaway.
• Visual properties, like hair lustre, shine, and oiliness.
• Wetting properties, which include spreadibility of water and sebum.
• Resistance to surface abrasion, like surface wear and tear of hair.
• Inter-fibre adhesion, which entails hair body and appearance.
With the current fashion trends, many consumers are using double chemical treatments and heated styling appliances, which cause extensive damage to hair and require deep conditioning. In addition, older segments of the population with characteristically dry, brittle and fragile hair also require intense conditioning. Consumers pressed on time prefer to get the conditioning from a shampoo rather than following a complete conditioning and styling regimen. At present there are many conditioning ingredients at a formulator’s disposal, but there is not a perfect conditioning agent that can deliver both exceptional conditioning attributes and show multifunctional benefits. As a result there is an increasing demand for conditioning ingredients that can both be delivered from a shampoo and possess multiple benefits. With stress on multifunctional and multi-benefit ingredients, “the one in more approach” in choosing an ingredient by a formulator is becoming more common. Various factors such as a weakened economy, ease of manufacturing and formulation, and the need to rein in costs are leading to such a shift. Formulators are looking for ingredients that can accomplish more than one function. The multifunctional approach was established from a series of tests using a combination of Merquat 2003PR and Merquat 5210. Merquat 2003PR (polyquaternium-53) is an amphoteric linear terpolymer, made up of acrylic acid, MAPTAC and acrylamide, supplied as a 20% solution in water. Merquat 5210 (polyquaternium-52 and laureth-16) is a cationic crosslinked copolymer, supplied as 40% in laureth-16 wax. Merquat 5210 is preservative free and is made up of N, N-dimethylaminoethyl methacrylate ethyl sulfate quaternary salt (DMAEM-ESQ), dimethyl acrylamide (DMAA) and PEG-dimethacrylate. This combination was found to help in hair conditioning, improve foam in a sulfate-free and sulfated shampoo, improve colour retention properties and provide silicone-like attributes from a shampoo formulation.
Research methods include:
• Formulation of shampoo bases using polyquaternium-53, polyquaternium 52 with laureth-16, the combination of polyquaternium-53, polyquaternium-52 and laureth-16, guar hydroxypropyltrimonium chloride, polyquaternium-55, polyacrylate-15 (and) polyacrylate-17, and amodimethicone.
• Measurement of wet combing forces.
• Sensory evaluation of polyquaternium- 53, polyquaternium-52 and laureth-16, and their combination.
• AFM build up studies comparing individual polymers and combination with guar hydroxypropyltrimonium chloride.
• Colour retention studies.
• Rheology studies.
Formulation of shampoo bases
Shampoo bases using the surfactants listed below were formulated and used in all the studies. The bases are shown in Table 1:
• Sodium laureth sulfate.
• Cocamidopropyl betaine.
Diastron wet combing results
The conditioning effect of polyquaternium-53 and polyquaternium 52 with laureth-16 was evaluated by wet combing test using Diastron MTT160 Mini Tensile Tester equipped with MTTWIN Version 5.0 software. The information on the per cent improvement in wet combing on hair tresses after treatment with the shampoo bases versus control shampoo base was studied. In this method six bleached, level six, Caucasian hair tresses each weighing around two grams and six inches in length were used for each treatment. The tresses were treated with control shampoo base without polymers by following a standard procedure. The tresses were combed using a Diastron mini tensile tester. The hair tress was attached to the load cell using the upper grip and the hair was combed at a rate of 300 mm per minute from root to tip. The tresses were combed five times and the total mean combing work was measured and recorded. Total combing work is the amount of work required to comb the full-length of the tress (120 mm) expressed in milliJoules (mJ). This data provides information for the convoluted effect of combing plus detangling. The tresses were then treated with shampoo bases shown in Table 1 using the above procedure and then combed again and the total mean combing force was measured and recorded. The per cent improvement was calculated as shown below and recorded. A higher value of per cent improvement is indicative of easier combing and detangling (see equation). Figure 1 illustrates how the combination of polyquaternium-53 with polyquaternium 52 and laureth-16 compares to individual polymers and guar hydroxypropyltrimonium chloride. The per cent improvement with polyquaternium 53 and laureth-16 and the combination of polyquaternium-53 with polyquaternium 52 and laureth-16, closely resembles each other showing that there is not much difference between these polymers although a combination shows a higher value of per cent improvement. The per cent improvement obtained with guar hydroxypropyltrimonium chloride was very low, showing that it does not contribute much to wet combing and detangling.
In this test, the hair tresses are shampooed by hand and evaluated for foam and feel properties during shampoo application, rinsing and after rinsing. Some of the parameters evaluated include the initial flash foam, total foam, hair softness during shampoo application, hair detangling during shampoo application, hair softness during rinse, hair softness after rinse, hair detangling during rinse and hair detangling after rinse. Virgin, Caucasian, level four hair tresses, weighing 17.5 g, 6 cm wide and 27 cm in length were cleaned with sodium laureth sulfate by following a standard procedure and dried. The tresses were then treated with control shampoo without polymers and evaluated for the above mentioned properties. These values were used as an anchor to evaluate the other bases. The tresses were then treated with the bases shown in Table 1 and evaluated again. The results are illustrated as a spider graph as shown in Figure 2, with the control anchored at three.
AFM build up results
Caucasian, level six bleached hair tresses were shampooed using the shampoo bases from Table 1 by following a standard procedure. The tresses were allowed to dry overnight in a humidity chamber at a relative humidity of 65%. The tresses were shampooed ten times over a period of ten days. They were labelled and submitted for AFM studies. A sample of hair from each tress, about 1 inch from the tab was used for this study. A 15-micron region was used as a focal point. The following images confirm that the build up in case of polyquaternium 52 and laureth-16, polyquaternium-53 and their combination was negligible. The build up could be clearly seen with guar hydroxypropyltrimonium chloride.
The study of shear stress against shear rate is called slip. It determines the ability of a substance to flow in layers. A high peak’s shear rate means high slipperiness leading to an increased ease of application on the hair and greater ease in running ones fingers through their hair. The purpose was to check if the polymer gives the same slip that is expected from a silicone. This test was conducted using TA instruments AR 2000, Stress controlled rheometer. A continuous ramp test using shear stress versus shear rate was measured. A typical curve is shown below in Figure 3. The results are shown in Table 2. The results show that a combination of 0.2% polyquaternium-53 and 0.1% polyquaternium 52 with laureth-16 gives a high shear rate value which translates to a very good slip. The shear rate shown by this combination is better than dimethicone at 0.3% and almost comparable to dimethicone at 1%. This illustrates that the polymer combination functions as a silicone.
Hair colour retention test
The hair colour retention test was conducted on virgin level 12 white hair tresses. The tresses were treated with 8 g of L’Oreal permanent colour R68 mixed with 20V developer for 25 minutes. The swatches were rinsed with water running at a rate of 3.8 lit/min for 1 minute. The swatches were allowed to dry overnight in a humidity chamber at a relative humidity of 65%. They were shampooed with the shampoo bases, the compositions shown in Table 1. The swatches were shampooed a total of 20 times and readings were taken at an interval of 5, 10, 15 and 20 washes. The Hunter Tristimulus L, a, b values were measured using a Hunter Colorimeter LabScan XE (Hunter Associates, Reston, VA). The data was expressed as total colour change ?E = [?L2 + ?a2 + ?b2]1/2 before and after washings. The ?E values are the average of measurements performed at several positions. A lower ?E value corresponds to a lesser amount of colour fading. The ?E values are shown in Table 3. The results show that combination of polyquaternium-53 and polyquaternium 52 with laureth-16 has the lowest ?E value indicating that this combination provided the best colour retention. It is to be noted that this test was conducted by utilising a shampoo (a rinse off system) and a very low concentration of polymers was very effective. If these polymers are added to a conditioner and a leave-in product and tested as a total system, the colour protection property could be enhanced.
The recently introduced Merquat 5210 and 2003PR provide a novel multifunctional benefit approach different from the existing conditioning polymers. This combination provides the benefits of a conditioning ingredient with the addition of numerous features, such as colour protection – the ability of the two polymers to protect colour was significant. Colour protection was even significant after 20 washes. Also, the combination of Merquat 2003PR and Merquat 5210 provided a silicone-like feel. The combination could function as a silicone as well as a conditioning agent, a rare multifunctional benefit.
Dr Narjis Askar is a staff scientist at Nalco. She has over ten years of experience in the area of cosmetic chemistry especially permanent and semi permanent hair colors, testing and manufacturing. She is involved in study of cosmetic polymers in terms of their interaction with hair and skin. Her principal activities involve studying the benefits of different polymers and applying these to keratin substrates. Her focus is to translate scientific insights into consumer relevant benefits. She has presented at various trade shows and technical seminars.
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Acknowledgement We would like to thank Mike Kamrath for his AFM work.