The featured chemical compound for this month is one that is used extensively in cosmetic, personal care, and other products. Polydimethylsiloxane is a silicon-based compound that has excellent rheological (flow) properties (1).
In haircare products silicon-based compounds initially got a bad rap as being non-water-soluble and hence accumulating in hair, but in fact depending upon how they are formulated, many silicone-based products are in fact water soluble.
PDMS compounds such as amodimethicone, are effective conditioners when formulated to consist of small particles and be soluble in water or alcohol/act as surfactants (especially for damaged hair), and are even more conditioning to the hair than common Dimethicone and/or Dimethicone copolyols.
source: Wikipedia.org: Polydimethylsiloxane#Hair
Here is more info about the history of research into silicone build-up in hair: naturallycurly.com: Silicone Hair Products: Not so bad after all
It turns out that some silicon-based products may actually be good for hair and are also water soluble, hence not leading to the “build-up” problems mentioned in some places.
Personally I’ve started using some products which contain silicone-based compounds and have found that I still don’t need to use shampoo, in fact I usually just prefer to soak my head under water to cleanse it naturally. There is no buildup or negative side and in fact the conditioning side is probably benefiting my hair a lot.
1. Wikipedia.org: Polydimethylsiloxane