Many people may not know the specific difference between liquid crystal emulsions and ordinary emulsions. Our usual emulsions basically rely on oil-in-water emulsifiers and oil-in-water emulsifiers.The liquid crystal emulsifying system is different. It relies on the assembly and rearrangement of various emulsified molecules to form a layer-by-layer layered network structure. It looks like an onion at the microscopic level. Stacked layer by layer, it is very similar to the lipid structure of the stratum corneum of our human skin.It is also this special structure that makes it excellent in terms of stability, water-locking ability, skin repair effect and skin feeling.Next, let's talk about it in layman's terms, how this liquid crystal layered structure is formed, how it is stabilized, and what practical use it has in skin care products.
I.Technological innovation: Emulsion microstructure
The liquid crystal emulsifying system is a special state between a liquid and a crystal. The biggest feature is that it has a neat alternating layered structure, and water, surfactants, and oils are arranged in an orderly manner layer by layer. This is also the core reason why it is closest to the structure of human skin.
A mature liquid crystal system is a three-dimensional network of countless bimolecular layers stacked on the micro level, with a dense and regular structure.Unlike the dispersion mode of ordinary emulsion particles, it relies on its own structure to form a gel network to stabilize the overall system. Without adding a large amount of thickener, it can have good consistency and stability.In the formula,
Peg 80 sorbitan laurate is an auxiliary raw material. It can gently adjust the molecular arrangement of the oil-water interface, so that the layered structure of the liquid crystal grows more regularly, and there will be no structural confusion or local cracking. It can be used as an additive for the formation of liquid crystal systems.
In simple terms, liquid crystal emulsions are a network of molecules assembled by themselves to form a body, which firmly locks oil and water in a layered structure. Not only is it not easy to deteriorate and stratify, but it can also trap moisture and skin care ingredients between the gaps and slowly release them.
II.Core mechanism
Liquid crystal structure, it is a process of gradual change and gradual progress.A simple understanding is the assembly process of molecules from chaotic to neat, from scattered to formed.The whole process can be roughly divided into four stages. The molecular state and system texture of each stage are different. Moreover, we can adjust the ratio of raw materials, production temperature and homogenization process to control the molding effect of the structure and adapt it to different skin care product needs.
Stage one：
When making emulsions at the beginning, we will first heat and homogenize and stir. At this stage, the temperature is relatively high. All emulsified molecules and grease molecules are evenly dispersed in the system, and they will spontaneously gather into small spherical micelles, wrapping part of the oil phase.At this time, the oil and water are only simply fused, and the whole is still in a messy and disordered state. The fluidity is very strong. The bottoming effect at this stage is very important.
MYRISTYL MYRISTATE can adjust the properties of the oil phase well, reduce the interfacial tension between the oil and water, and avoid the micelle getting together and agglomeration, so that the entire system is uniform and stable, and lay a good foundation for subsequent structural molding.
Stage two：
In the follow-up, as the system slowly cools and the moisture content stabilizes, the force state of the entire system changes, and the originally stable spherical micelle begins to become unstable.The emulsified molecules will slowly adjust their arrangement posture, no longer gather into balls, and gradually become columnar and flaky aggregates.This step is the transition stage. Although a complete liquid crystal structure has not yet been formed, the molecules have begun to become regular, and the arrangement density of the oil-water interface is slowly getting higher, preparing for the formation of layered structures.
In order to make this transition process smoother and avoid messy molecular arrangement, OILREE® MY749-B (
Bis diglyceryl polyacyladipate 2) is generally added to the formula.The adaptability of this raw material is particularly good. It can form a gentle coupling force with emulsified molecules and water molecules, actively guide the orderly arrangement of molecules, effectively prevent local structural deformities and uneven arrangement, and greatly improve the regularity of the final liquid crystal layered structure, so that the texture of the finished product is more uniform.
Stage three：
When the molecular arrangement density of the oil-water interface reaches a suitable critical state, the most critical step will be ushered in: the bimolecular layer is officially formed.This is also the core skeleton of the liquid crystal system that is truly formed.All emulsified molecules will be neatly arranged, the hydrophilic head is close to the aqueous phase, and the hydrophobic tail is firmly stuck in the oil phase, and the arrangement is particularly tight and regular, forming a stable oil-water isolation layer.Compared with the previous messy micelle structure, the order and stability of this bimolecular layer are not at the same level at all.
Stage four：
Finally, there is the stage of perfecting the overall structure. Countless regular bimolecular layers are constantly stacked, staggered, and extended to form many multilayer vesicle structures, which are finally intertwined into a complete and dense liquid crystal gel network.At this time, the system has both stability and practicality. When placed statically, it is a thick and stable cream. There are many nano-scale tiny gaps inside, which can firmly lock in moisture, oil and skin care active ingredients. It will not be lost easily, and it can be easily pushed away when applied, and the fluidity is particularly good.
III.Underlying logic
Many people may think that the liquid crystal structure is formed by a certain kind of raw material alone, but it is not.It can be formed stably and remain intact for a long time, which is the result of multiple forces working together.Simplicity can be classified into three points: hydrophobic interaction, interfacial bulk density, and hydrogen bond network.These three forces cooperate and restrain each other, so that the molecules can be assembled autonomously and in an orderly manner, and finally form a stable layered liquid crystal structure, which directly determines the texture and stability of the finished emulsion.
1. Hydrophobic interaction
The first is the hydrophobic interaction, which is the most basic driving force for the formation of structures.The hydrophobic tails of grease and emulsified molecules naturally dislike contact with water. In order to keep the system stable and reduce their own energy, they will spontaneously gather together and arrange tightly.This innate tendency to gather gives scattered molecules the basic conditions to assemble into micelles and stack into layered structures.
2. Interfacial bulk density
The second is the interfacial bulk density, which is simply the density of molecules at the oil-water interface, which directly determines what kind of structure can be formed in the end.If the molecules are arranged very loose, they will only form ordinary spherical micelles. If the density is moderate, they will become a soft worm-like structure. Only when the bulk density reaches a suitable high level can the molecules be spread out flatly and stacked into the layered liquid crystal structure we need.Usually when the formula is developed, everyone will adjust the ratio of emulsifiers and greases to accurately control this density to ensure the smooth formation of the liquid crystal structure.
3. Hydrogen bond network effect
Finally, there is the fixation of the hydrogen bond network, which is the key to the long-term stability of the structure.In the aqueous phase of the liquid crystal system, emulsifiers, additives and water molecules will form a large number of hydrogen bonds with each other to build a stable structured water layer.This layer of network can not only lock in moisture, but also fix the position of the bimolecular layer to prevent the layered structure from loosening, misalignment, and collapse.Among them,
Glycol distearate can participate in the construction of the hydrogen bond network, making the entire network denser and stronger, greatly improving the storage and shear resistance of the liquid crystal system, and it is not easy to go wrong with daily use and storage.
V.Recipe code
To make a high-quality liquid crystal emulsion, the core is to choose the right
Emulsifier and matching raw materials.The molecular structure, HLB value, and molecular morphology of the emulsifier will directly affect the molding effect of the liquid crystal structure.In simple terms, the HLB value is too high or too low. Only a medium value can form a layered structure smoothly.Molecules are regular long-chain forms, which are easy to be tiled and stacked, and molecules with messy structures will directly destroy the liquid crystal formation.At the same time, the emulsifying system with ionic action can make the interface bond stronger and the bimolecular layer structure more stable.
Therefore, when developing formulas, everyone will give priority to adapting emulsified raw materials with suitable molecular morphology and moderate HLB value to ensure the regularity and stability of the liquid crystal structure from the root cause, avoid structural defects, system instability and a series of problems, and maximize the skin care advantages of the liquid crystal system.
In the actual production formula, special additives are generally used to improve the quality of the finished product.MY965 (peg-100 stearate & glyceryl stearat) This raw material can well adjust the rheology of the system, help the liquid crystal emulsion stabilize and thicken, and strengthen the layered network structure; MY989 (polygyceryl-4 isostearate), MY987 (polyglyceryl-2 tetraoleate) ester system can optimize oil compatibility, so that the structure breaks more evenly when applied, the skin feels more delicate, and avoids heavy and false slippage.
VI.Segmented application scenarios
Relying on the advantages of gentleness and safety, advanced skin feeling, and strong stability, liquid crystal emulsification technology has now been widely used in all kinds of high-end skin care products, covering many fields such as repair, moisturizing, sunscreen, and sensitive skin care. It is the core technology of effective skin care products.
In barrier repair products, the liquid crystal structure can accurately simulate the stratum corneum of the skin, quickly repair the damaged barrier, relieve skin redness, dry itching, and sensitive problems, and maintain a stable skin state for a long time. It is the preferred system for sensitive muscles and postoperative repair products.Among high-end moisturizing products, its long-lasting water-locking ability is matched with a cloud-like dense skin feeling, which easily opens the gap with ordinary moisturizing products, and its texture and efficacy are more outstanding.
In sunscreen products, a regular liquid crystal network allows the sunscreen ingredients to be evenly spread out to form a complete protective film, which effectively reduces the problems of whitening, mud rubbing, and greasy after application, and stabilizes the activity of the sunscreen ingredients to ensure that the sunscreen effect does not decrease.Moreover, the whole system is gentle and non-irritating, and has strong compatibility. Whether it is adult skin care products or special products for infants and sensitive muscles, it can be adapted and has a wide range of application scenarios.
Hubei Mingya New Material Technology Co., Ltd.
