Beauty Tips For Body Care
Disclaimer: I have only completed my chemistry bachelor's and am currently (supposed to be) writing my thesis to get my honours degree. I still feel like I barely know chemistry and with skincare, knowledge of biology is also needed.Skincare science is something that really frustrates me because I hear a lot of things over and over again on social media that don't make sense to me. For example "hyaluronic acid can hold 1000 times its weight in water". This has been parroted so many times, and sometimes it's molecular weight, sometimes it's just "weight". From a chemical/physical stand point, how is this possible?Firstly looking at the molecular weight perspective.So HA is a chain of repeating units so the MW can vary, however for the sake of these calculations I will just be looking at on average, how many molecules of water can one repeating unit of a chain hold. The molecular weight of a single repeating unit of HA is roughly 422g/mol. Check the wikipedia page for an image the structure of hyaluronic acid.1000 times this is 422000g/molWater is 18g/mol422000/18 = 23444.44 molecules of water per unit of HA.This is insane. How would it do that? Looking at the structure of HA, it probably attracts water due to hydrogen bonding through the O and OH groups hanging out. Even through something like cross linking of polymers I don't think it's plausible.Okay time for calculations based on weightIf 1g of HA holds 1000g of water1g is 1.43*10^21 HA units1000g of water is 3.35*10^25 molecules of waterWhich means per unit of HA we are still looking at ~23000 molecules of water.I just found this and checked the citation, and that article does claim that 1g of HA can hold 6L (6000g) of water which is an even bigger claim without a calculation or citation.Another thing I always hear is that sodium hyaluronate is smaller than hyaluronic acid and can penetrate the skin deeper. However the structure is pretty much the same, perhaps somehow the sodium means the chain length of HA is lower and therefore "smaller"? This stuff I'm not sure about. If anyone has insight into any of this please let me know, I am just very curious about all of this.I'm not saying that HA doesnt work, I just want to highlight that we should question the science that we keep repeating. The "1000 times its weight" claim is on the paula's choice website and dermalogica's website but from my (limited) understanding I dont see how this is possible.ALSO correct my math if you want I am prone to mistakes.
Girls Blog 2015
Submitted by Great_Pomegranate
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