Linking anionic formulation with cationic compound: study in preservation for hair care applications

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In the development process of new cosmetics product, the formulator chooses different kind of molecules to assemble the formula considering functionality, compatibility and activity.

Surfactants are a key component in rinse-off cleansers, the most commonly used are anionic surfactants.

When offered a preservation system of a cationic nature, even experienced formulators, raise concerns about the compatibility aspect in anionic medium. the most immediate question is – would the preservative system hold its efficacy in an anionic formula?

Several studies were performed in recent years regarding the interaction between cationic polymers and anionic surfactants. the studies address the questions regarding the impact of said ingredients on formula performance (1) . Sharon Laboratories explored this matter, from our angle: antimicrobial efficacy. Two new preservative lines with cationic profile, Sharomix™ Amplify and SharoSENSE™ Plus were put to the test.

The study evaluated cationic nature preservative solution behavior, in both anionic and nonionic cosmetics formulas, for its antimicrobial activity.

An anionic surfactant-based liquid cleanser (SLES & CAPB) formula (see table 1) preserved by Sharomix™ AM24 (INCI list: Methylpopandiol, Caprylyl Glycol, Polyquaternium-80 and Didecyldimoniom Chloride), at a level of use of 0.5%. This ”phenoxyethanol–free” solution contains, in essence, two cationic elements incorporated into strong anionic medium.

Neutral facial cream formula (see table 2) based on Cetearyl Glucoside & Cetearyl Alcohol nonionic emulsifier (HLB =10), Caprylic Capric Triglycerides and Ceteareth-20, preserved by 0.5% of Sharomix™ AM24.

The performance of Sharomix™ Amplify preservation system remained high at both evaluated formulas.

Superior antimicrobial performances were demonstrated by SharoSENSE ™ Plus line as well.

While Sharomix™ AM24 contains Caprylyl Glycol as a booster, SharoSENSE ™ Plus, comprises of Maltol and a choice of cationic enhancers (Polyquaternuim-80, Polyquaternium-2 , Didecyldimoniom Chloride) brings customer a “solvent-free” solution. The essence of SharoSENSE™ Plus preservation efficacy relays on synergy between its components.

Comparative challenge tests results show cationic nature preservative solution maintain performances and were not negatively impacted by anionic formula type, as can be seen in the table below.

The preservative’s system composition and level of cationic ingredient were carefully designed in both preservative systems, to allow the best antimicrobial performance, with no interruption to the formula.

(1) Cornwell. P. A, A review of shampoo surfactant technology: consumer benefits, raw materials and recent developments. International Journal of Cosmetic Science, 2018, 40, p. 16–30

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