Going Dioxane-Free: Replacement Emulsifiers and Solubilizers
In parts one and two of this blog series, we discussed how ethoxylation is a tremendously useful tool for building surfactants that is under fire due to concerns over a potential byproduct, 1,4 dioxane. With stricter dioxane regulations pushing formulators away from traditional ethoxylates, what are the alternatives? In this segment we’ll discuss alternatives for emulsifiers, including oil in water (o/w), water in oil (w/o), and emulsifiers for fragrance microemulsions, sometimes referred to as solubilizers.
Emulsifier Alternatives
When looking for ethoxylate (PEG) replacements, formulators are expected to weigh several factors: biorenewable content, toxicity profile, ease of use, efficiency, cost, and how well the ingredient fits brand positioning.
For small molecule emulsifiers to replace common emulsifiers like Steareth-2 and Steareth-20 along with polysorbates, some options include:
- Glyceryl Stearate with Stearic Acid: Typically 100% naturally derived, though the stearic acid is very pH-sensitive. This has become a workhorse option today for simple, economical o/w body lotions.
- Polyglyceryl Esters: This is an incredibly diverse class of emulsifiers with various chain lengths and substitution patterns, allowing for robust emulsion stability and good control over aesthetics. Polyglyceryl-3 Oleate (Cola®Mulse 3GO), for example, is an outstanding w/o emulsifier that’s suitable as a co-emulsifier or as a key ingredient in oil cleansers to incorporate small amounts of water-based additives with high clarity.
- Amino Acid Esters: This emerging, innovative group of emulsifiers can be naturally derived and customizable, but come with a higher price tag for premium facial care formulations.
- Phosphate Esters: This class of high biobased emulsifiers is well known for their highly elegant feel and ability to stabilize o/w emulsions at low or high viscosity. Cetyl Phosphate (Cola®Fax CPE) and Potassium Cetyl Phosphate (Cola®Fax CPE-K) are go-to emulsifiers for organic sunscreen or skin protectant formulations.
For those preferring polymeric emulsifiers, there are synthetic acrylate-based options (low cost but petroleum-derived), natural cellulosics and crosspolymers, and silicone-based options (luxurious feel but facing other consumer perception challenges).
Fragrance Solubilization Options
Fragrance solubilization is really about creating microemulsions; emulsions with oil droplets so tiny that light passes through without getting refracted, keeping products crystal clear. This typically requires high-HLB emulsifiers at relatively high product loading, though product performance varies widely by emulsifier chemistry as well as the fragrance or essential oil chemistry. Due to the unique challenges of this application area, this has been one of the hardest application areas for formulators to find simple replacements.
The leading dioxane-free approaches include:
- Polyglyceryl Esters: Benefit as mentioned before by bio-based content, though no single “workhorse” product has emerged yet. Formulators usually need to blend different types for each specific formula.
- Small Molecules: Some surfactants like Decyl Glucoside (Suga®Det D) have been demonstrated to have some efficacy, in particular for highly polar fragrances.
- Surfactant Combinations: Using a combination of surfactants can be extremely effective, though this adds multiple ingredients to the label.
Testing shows that some newer technologies like Sorbitan Oleate Decylglucoside Crosspolymer (Poly Suga®Mulse D9) can actually outperform traditional ethoxylated solubilizers for certain essential oils. The key is matching your solubilizer choice to your specific application and fragrance.
What are your challenges as you search for lower dioxane alternatives in the formulation work you do? Reach out and let’s discuss how we can best serve your needs!
