In this discussion, Tony O'Lenick looks to Tim Kenny of Elementis to explain the differences in chemistry between PEG-8 dimethicone and PEG-8 dimethicone meadowfoamate and what they mean to formulators.
PEG-8 dimethicone is one of a series of silicone polymers that have a water-soluble polyoxyalkylene group on a silicone backbone. These materials are amphiphilic since they have two groups on the same molecule that are insoluble in one another in pure form. The presence of the water-soluble group makes this material surface active and water-soluble. PEG-8 dimethicone can be added to formulations to provide light hair conditioning.
PEG-8 dimethicone meadowfoamate is a fatty ester of PEG-8 dimethicone. It has a polyoxyethylene group on a silicone backbone as well as a very unique fatty group attached to the polyoxyethylene group. Figures 1 and Figure 2 show the structure.
The presence of the meadowfoam group on the ester provides enhanced oil solubility. This, in turn, provides improved wetting and spreading on the hair, and improved wet comb and dry comb properties. Figure 3 shows the results of a tensile strength test performed on unprocessed hair treated with 2% PEG-8 dimethicone in water, or 2% PEG-8 dimethicone meadowfoamate in water.
Based on the results from the tensile tester, and statistically analyzed for significance, the strength of unprocessed virgin or normal hair was increased by 27% after treatment with the 2% PEG-8 dimethicone meadowfoamate in water, whereas treatment with PEG-8 dimethicone had no effect, negative or positive, upon hair strength.