The “Most Searched Products” section in Innovadex’s New Trend Tuesday e-newsletter highlights several ingredients each week that are popular with users of the search engine. One that you may have noticed in the recent past is SEPIGEL™ 305 (Polyacrylamide, CI3-14 Isoparafin, Laureth-7-Seppic), a liquid dispersion polymer (LDP) used to thicken oil in water emulsions and gels. I’ve designed the following overview as a research reference for formulators on this commonly used ingredient.
Launched around 1990 by SEPPIC, SEPIGEL™ 305 was one of the first LDPs on the market and represented a significant improvement over Carbomers in terms of formulating ease and low PH tolerance. SEPIGEL™ 305 is produced by crosslinking polymerized 2-Acrylamido-2-methylpropane sulfonic acid (AMPs) with a difunctional acrylamide monomer like N,N’-Methylenebisacrylamide. The low PH thickening ability of SEPIGEL™ 305 is due to the low PKa of the sulfonic acid group compared to the carboxyl group of acrylate based polymers.
LDPs are common thickeners used in personal care products and have displaced powdered Carbomers in popularity. They are produced by polymerizing monomers in a water-in-oil emulsion and the water is then removed. A hydrophilic surfactant is added to facilitate hydration when added to water.
- Extremely easy to process, hot or cold
- PH stable 3-12
- Can formulate excellent low PH self-tanning products or Salicylic acid products
- Excellent skin feel with good pickup
- Can make stable emulsions without using additional emulsifiers
- May be cheaper on an active basis then powdered Carbomers and acrylates
- Compatible with insoluble salts like iron oxides or zinc oxide (>PH7). Carbomers are not compatible
- The polymer in LDPs can settle out over time
- Can’t make clear gels
- Very salt sensitive
- 7% active polymer 59.5K cps, .6% Sodium Chloride
- 2% active polymer 60K cps, 0% Sodium Chloride
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