Cleansers 101 - Selecting the Right Surfactant

Role of Surfactants in Cosmetics

• Detergents
• Wetting agents
• Emulsifiers
• Foaming agents, and
• Dispersants

How Do Surfactants Work?

• Anionic surfactants are incorporated for their surface activity (negative charge polar head groups like carboxylic acid, sulfates, sulfonic acids, and phosphoric acid derivatives)


• Cationic surfactants are incorporated for their electrostatic attractive properties to skin and hair, and substantivity (positive charge polar head groups like amines, alkylimidazolines, alkoxylated amines, quaternary ammonium)


• Non-ionic surfactants are incorporated as emulsifiers, conditioning agents, and solubilizers/coupling agent (no charge and represented by alkylene oxides, polyglucosides, fatty alcohols, ethanolamines, dimethylamine oxides)


• Amphoteric surfactants are incorporated as secondary surfactants to help boost foam, improve conditioning, and reduce irritation (zwitterionic with positive and negative depending on the pH of the environment)

Surfactant Classification

Functionality Matrix of Anionic Surfactants

Functionality Matrix of Cationic Surfactants

Functionality Matrix of Non-ionic Surfactants

Functionality Matrix of Zwitterionic Surfactants

Surfactants Selection Made Easy

1. Consider the interaction of ingredients and how a surfactant-based cleansing system will be positioned in the marketplace


2. Chose the raw material manufacturers because they might employ different processes:
   1. There is always a concern - as relates to manufacturer variations - regarding the quality and performance of ingredients
   2. There can be variances in the consistency of ingredients from batch to batch and lot-to-lot
   3. Surfactant specifications are critical to ensuring viscosity control, color, odor, pH, salt content, and foaming/cleansing characteristics

1. Detergency to remove soil - e.g., in shampoos and soap


2. Wetting to improve the contact angle between a solution and a substrate - e.g., in the coloring of hair and applications of permanent wave lotions


3. Foaming for appearance - e.g., in shampoos, bubble bath, and laundry detergents


4. Emulsification to form a stable mixture of two incompatible phases to include oil-in-water, water-in-oil, multiple phases, clear micro, alcoholic, nano-, and refractive index matching - e.g., in skin and hair creams and lotions


5. Solubilization of insoluble components such that they are compatible in an incompatible system - e.g., in perfumes and flavors

Practical Aspect on Surfactant Chemistry

• Quality of the foam
• Structure and amount (e.g., creamy, loose, tight, quick breaking, etc.), and
• Cleansing action

Important Considerations While Formulating with Surfactants

1. Choosing the right surfactant type/co-surfactant system which has the greatest solubility for the oil phase.
2. Adjusting the ratio of surfactant to co-surfactant.
3. Determining the ratio of oil to surfactant/co-surfactant mixture.
4. Add sufficient water to find the right microemulsion region.

Fundamentals to Successful Cleanser Construction

• Determination of which part of the body is to be cleansed
• Foam size and structure
• Ease of building foam
• Feel during application and after rinse-off
• Viscosity during dispensing and use; and
• Deposition of active ingredients

1. Water


2. Primary Surfactant(s) - The workhorse ingredient(s) required to remove soil from a substrate


3. Co-Surfactant(s) - Used to add structure to formula (and could add foam density); conducive to forming a micelle structure that confers higher viscosity (Alkanolamide MEA and Betaines being the more common options)


4. Rheology Modifier(s) - There are two types of rheology modifiers: polymeric and high melting point wax. Polymeric thickeners include Acrylate-chemistry, cellulosic, and gums (guar, xanthan and locust). High molecular weight/melting point waxes (e.g., Stearyl Alcohol and PEG esters) produce crystalline structures that provide a suspension of insoluble components. Their performance properties include:
   • Controlling rheology and yield stress - modifying the appearance, flow, and texture to alter pour and at-rest characteristics
   • Stabilizing oils and suspended particles
   • Thickening of surfactants - i.e., those that do not thicken with the addition of salt
   • Aesthetic modification - e.g., to impart a modified feel during application
   • Viscosity stabilization - i.e., preventing viscosity drift during long-term high-temperature stability testing


5. Preservative(s) - Since cleansing product tend to be based on aqueous systems at relatively neutral pH, preservatives are critical to maintaining a micro-organism-free system


6. pH Adjuster(s) - Alkaline and/or acidic (e.g., sodium hydroxide and citric acid)


7. Miscellaneous Functional Ingredients -
   • Emolliency & Moisturization (e.g., glycerin, fatty acid esters, polymers),
   • Rinse-off aids
   • UV Stabilizers for colorants
   • Pearlizing agents
   • Antioxidants
   • Color
   • Fragrance

Face Cleanser Formulations

Cetaphil Daily Facial Cleanser

Procedure

• Add Methacrylate Copolymer to deionized water. Add Glycerin, Preservatives, EDTA to water system.
• Add Sarconsinate & Sulfate with gentle mixing. Adjust pH with Sodium Hydroxide (optional) to desired pH.
• In separate vessel, add all PEG-x, along with Panthenol and heated to melted. Add this to the Aq phase and mix until uniform.
• Add combination of masking agent and butylene glycol, mix until solubilized and add to above mixture.

Neutrogena Naturals Purifying Facial Cleanser

• Gently removes impurities & improves complexion for fresh, clear skin.
• Willowbark bionutrient rich cleanser detoxifies pores.
• Dermatologist recommended brand. No harsh chemical sulfates, parabens, petrochemicals, dyes, and phthalates.

Procedure

• Put the water in the main mixing vessel and slowly add Guar.
• Add the surfactants (betaine, hydroxysultaine, sulfoacetate), one at a time, and stir until fully dissolved.
• Add rest (glucoside, benzoate, bark extract, frag).

Hair Cleanser Formulations

EverPure Volume Shampoo (L’Oreal) for Fine Hair

• Sulfate-free color care system
• Exclusively for color treated hair
• Anti-fade system. 100% sulfate-free
• No harsh salts
• Natural botanicals, 100% vegan

Procedure

• Add associative thickener to Deionized Water and start mixing.
• Add Sodium Laureth Sulfate with gentle mixing. Mix until uniform. 
• Adjust pH to 6.5-6.7 with Sodium Hydroxide (18%). Mix until uniform.
• Add Cocamidopropyl Betaine and rest of surfactants with mixing. Mix until uniform.
• Add rest of ingredients to the batch with mixing. Mix until uniform.
• Adjust pH to 4.8-5.2 with Citric Acid (50%). Mix until uniform.

Don't Let Complicated Surfactant Selection Rules Hinder Attainment of your Perfect Formulation!

Find Suitable Surfactants / Cleansing Agent for Your Product