Study On The Mechanism And Applications Of Hydrogenated Lecithin To Form Liquid Crystal

Hydrogenated Lecithin?HLC?is a natural amphoteric surfactant hydrogenated from lecithin,which can form liquid crystal structure in water or in emulsion systems as an emulsifier.Compared with emulsions made from non-naturally derived emulsifiers,its safety can also been ensured.Therefore,HLC based liquid crystal emulsions have broad application prospects in the development of the cosmetics industry.Firstly,the mechanism of liquid crystal formed by HLC was studied by phase diagrams,including the phase diagrams of HLC/Water system,HLC/E-EN8/Water system,and HLC based emulsion systems prepared by different types of oils.For the HLC/water system,when the mass fraction of HLC is between 10 wt%to 37 wt%,and the temperature is under 70°C,lamellar liquid crystals formed.In the HLC/E-EN8/water system,The microstructure of the liquid crystals is different at the different ratio of HLC/E-EN8,but all of them are lamellar liquid crystals,and when the radio of HLC/E-EN8 is between 6:4⁸:2,it can form clear Maltese cross liquid crystal.In the emulsion systems,caprylic acid capric triglyceride and avocado can form liquid crystal more easily than squalane,the addition of octadecanol alchol can significantly increase the area of the liquid crystal phase,and increased the distribution of HLC at the interface as well,which made the lamellar liquid crystal structure more easier to form.Secondly,factors like the amount of HLC and cholesterol,the type of co-emulsifiers,fatty alcohol and polyols,the type and amount of oils and inorganic salts,pH value of aqueous phase,the homogenization temperature,time and power on HLC based liquid crystal emulsions were studied.The results showed that liquid crystal emulsions can be obtained when HLC is from 2⁴ wt%.Compared to non-polar oils,emulsions prepared by oils with a polarity index about 20 showed more and regular liquid crystal structure,and the addition of caprylic acid capric triglyceride or jojoba at 5%is preferable.Among the co-emulsifiers,only the emulsion prepared by E-EN8 had the Maltese cross liquid crystal structure.With the increase of E-EN8,the amount of liquid crystal gradually decreased,and the optimum addition amount is about 1%.The addition of cholesterol was benefit to the amount,regularity and brightness of liquid crystal structure,but the cholesterol over 2%cannot been completely dissolved in oil phase.Cetyl Alcohol is superior to octadecyl alcohol and dodecyl glycol in froming liquid crystal structure.Glycerol,1,2-propanetriol and 1,3-butanediol showed no obvious difference in preparing liquid crystal emulsions.With the increase of NaCl or MgSO₄,the amount and regularity of the liquid crystal decreased,and the over addition of MgSO₄ was more easier to destroy the liquid crystal structure than NaCl.The initial pH of the aqueous phase had no significant effect on the pH value of the emulsions,but the aqueous phase of strong acids or alkalies would destroy the liquid crystal structure to some extent.The emulsification temperature,homogeneous power and homogeneous time has no significant influence on the liquid crystal but have a little impact on the partical size.Finally,the application properties of the Optimal formula of HLC based liquid crystal systems were characterized,including stability,in-vivo stability,moisture ability,and sustained-release property.The results showed that the liquid crystal structure disappeared after being stored for 1 month at room temperature.The Maltese cross liquid crystal structure firstly became irregular and then completely disappeared in 5 min after application on the medial arm.The HLC based liquid crystal emulsion has a higher moisturizing performance and sustained-release properties than the common emulsion,but not as good as the alkyl glycoside system.