Silicones come in many forms, offering infinite possibilities for formulators. They can bring sweet softness and luster to hair care products, provide luxurious texture to skin preparations, and have excellent spreadability, durability and protection. Sex.
Silicon (Si) is the second most abundant element on earth; it is chemically bonded to oxidation, just like silicon dioxide, or SiO2, the natural basis of sand. Usually, manufacturers and consumers mistakenly believe that silicones are petroleum-derived petrochemical products, but in fact, they are synthetic products made from sand or quartz, and are one of the most abundant minerals on the planet. Silicone is a term used for materials in which silicon combines with oxygen in a linear polymer matrix. Si-O (silicon-oxygen bond) and Si-C (silicon-carbon bond) allow free rotation, which allows these molecules to adopt the lowest energy configuration at the interface. This leads to ultra-low surface tension values compared to organic polymers. With these unique properties, silicones are ideal for many personal care applications.
Volatile silicone oil
Volatile silicone oil is composed of cyclic and linear molecules with a viscosity of less than 5 cst. The term cyclomethicone refers to a series of cyclic silicone compounds. The cyclomethicone with low heat of vaporization and low viscosity gives the skin a short-lived, non-greasy and non-cooling effect. It helps to improve the redness and spreadability of creams and lotions. Cyclomethicone can be used as a volatile carrier and is compatible with various cosmetic ingredients. Cyclomethicone can be used alone or mixed with other beauty liquids to provide a liquid base for various beauty ingredients. It has good solubility in most anhydrous alcohols and many cosmetic solvents. Cyclomethicone and simethicone (<5 cst) have been widely used in antiperspirants, deodorants, hair sprays, cleansing creams, skin creams (Formula 1), lotions and stick products, bath oils, sunscreens, shaving products And cosmetics. Due to its volatility, cyclomethicone must be added to the formulation at a temperature below 60°C.
Polydimethylsiloxane is the INCI name for a series of alkaline silicones used as base fluids in many personal care formulations. These inert polymers are optically transparent, odorless and non-flammable. They are commonly referred to as silicone oils, dimethyl polysiloxane and polydimethyl siloxane, and their viscosity ranges from 5 cst to 1 million cst. Low-viscosity (5 to 50 cst) and medium-viscosity (50 to 1000 cst) polydimethylsiloxanes are widely used in skin creams (Formula 1), lotions, sun creams, bath oils and hair care products. High viscosity polydimethylsiloxane (60,000 to 100,000 cst) is commonly used in hair care products. The low surface tension of polydimethylsiloxane allows it to be finely and evenly distributed along the hair shaft, resulting in a uniform conditioning effect. When applied to the hair, they quickly form a protective film and lock in water to optimize strength and prevent premature washing off of dyes and colors. In skin formulations, they form a smooth, horizontal film, act as an effective emollient, and help spread other ingredients and active ingredients. Non-volatile simethicone is easily incorporated through the oil phase under gentle heating, and is usually mixed with other emulsifying waxes such as cetearyl alcohol.
Dimethiconol, also known as silicone rubber (Figure 3), is a polymer similar to polydimethylsiloxane, in which two chain terminal methyl groups have been replaced by hydroxyl (-OH) . Two blends of dimethiconol were developed, and their CTFA names are (i) dimethiconol (and) dimethiconol; (ii) cyclomethiconol ( And) Dimethiconol. They are dispersions of very high molecular weight silicones in polydimethylsiloxane or cyclodimethylsiloxane. They provide adjustable conditioning effects that make unhealthy, damaged hair look and feel great. As the foundation of essence-type leave-in conditioners, they ensure that the hair has silky softness and velvet feel, and has excellent gloss properties.
The unique properties of dimethiconol are widely used in hairy coats, which can significantly alleviate problems such as split ends. In this hairy scale preparation, volatile cyclopentasiloxane is used as a temporary temporary conditioner. As it evaporates slowly, it improves the wet combability of the hair, leaving behind non-volatile dimethiconol that enhances gloss. The system improves the combing effect of dry hair and provides silky feel to the hair after use.
Synthesize organosilicon surfactants so that they contain both organosilicon and water-soluble groups in the same molecule. The result is a series of compounds with different and controllable solubility in oil, water and silicone. One of the common silicone surfactants is dimethicone copolyol.
Dimethicone copolyol is an amphiphilic compound designed to help prepare water-in-silicone or water-in-silicone emulsions. There are various types of dimethicone copolyols on the market, which generate a series of HLB values due to the presence of two or more mutually insoluble groups (Table 3). Generally, low HLB, soluble (silicon) siloxane skeleton of silicone and higher HLB, more soluble (hydrophilic) polyoxyalkylene component. Usually, polyethylene glycol (PEG), polypropylene glycol (PPG) or both are grafted onto the polydimethylsiloxane backbone in different ratios.
Cyclopentasiloxane (and) PEG / PPG-18 / 18 Dimethicone is a kind of dimethicone copolyol, which is widely used to prepare common silicone oil in antiperspirant, skin care and color cosmetic formulations Water-in-water emulsion. The material's low surface tension and effective wetting properties help stabilize the emulsion while providing a unique and soft skin feel.
Wetting is a surface effect that can characterize the behavior of droplets deposited on a solid/liquid substrate. For example, placing water droplets on a plastic plate will form tight spheres, indicating poor wetting. If the wetting agent is subsequently added to the water, the droplets will not form a spherical shape, but will spread across the surface of the plastic sheet. The Draves test is an established method to determine the wetting effect. It measures and compares the time required for the cotton "strand" to sink into the test solution at a specified temperature. The shorter the time, the better the performance of the wetting agent. The test uses a 0.1% dimethicone copolyol solution (Table 2)
In general, low molecular weight PEG/PPG polymers have faster wetting properties compared with similar products of high molecular weight. This means that a rapid wetting effect can be achieved by appropriately selecting the molecular weight of the dimethicone copolyol.
Reducing surface tension is one of the main properties of silicone surfactants. The fat content of the methylene (-CH2-)-rich molecule limits the surface tension to about 30 dynes/cm². However, silicone surfactants are mainly methyl (-CH3), which reduces the achievable surface tension at a lower level in the range of 20 dynes/cm2.
PEG/PPG polydimethylsiloxane is used as an emulsifier to prepare water-in-oil and silicone-in-water emulsions. It can be used to prepare products containing low-concentration wax and high-concentration water, thereby providing creams and lotions with a mild and easily dispersed skin feel. PEG/PPG polydimethylsiloxane can be easily structured along the Si-O-Si bond to adopt the lowest free energy state. This enables the production of emulsions with useful low free energy, thereby providing enhanced stability. Compared with the conventional without emulsifier, high surface activity has other advantages. For example, cold working techniques can be used to produce water-in-silicone emulsions prepared with silicone emulsifiers. This emulsifier approach is widely used in color cosmetic formulations (Formulation 3) because it improves the spreading and leveling properties of color pigments.
When preparing silicone oil in water or water in oil emulsion, PEG/PPG dimethyl silicone oil should be added and mixed into the silicone oil phase or the oil phase. For simplicity, it is best to prepare the water phase in a separate tank. Electrolytes (such as sodium chloride) should be pre-dissolved in the water phase to increase viscosity and help form a stable emulsion. Slowly add the water phase to the silicone phase or the oil phase to ensure complete and uniform emulsification. High speed mixing with high turbulence mechanical mixer. Continue high shear mixing for 10-30 minutes to produce a smaller particle size distribution and homogenize if necessary. No heating is required during the emulsification process.
Silicone elastomer gel
In today's cosmetics market, consumers need efficient products with perfect sensory characteristics, especially high-end brand products. Silicone elastomer gels (Figure 5), also known as silicone crosslinkers, provide an exceptionally ideal skin feel for the most innovative and flawless personal care development. They provide a dry, non-greasy but silky smooth skin feel while quickly absorbed into the skin. The silicone elastomer is based on cross-linked dimethylsiloxane and is provided in the form of a swelling gel containing various siloxanes such as cyclodimethylsiloxane or dimethylsiloxane. The INCI name for silicone elastomers usually includes the term "crosslinked polymer". The INCI name of silicone elastomer was given in the "Conventions for the Nomenclature of Silicone Silicones" published on August 13, 1999.
Silicone oil has no possibility of cross-linking, so the molecular backbone has high "flexibility" and a high degree of freedom of rotation, which means that silicone oil can remain liquid even at high molecular weight. In contrast, these elastomers have a limited degree of rotation due to the cross-linked structure (a key factor in determining polymer performance). The high crosslink density increases the stiffness/hardness of the crosslinked polymer. There are many types of crosslinked polymers on the market, in the form of elastomer gels, powders, emulsions or surfactants.
Silicone elastomer gels are generally used as thickeners for silicone encapsulated water formulations without heating. Because of their inherent compatibility with a variety of lipophilic active ingredients (for example, fragrances, UV filters, anti-aging active ingredients), they can be used as stabilizers. They provide a silky, smooth effect and reduce the viscosity of a given formulation. They are widely used in skin care, hair care, color cosmetics, antiperspirants and sunscreen formulations. In addition, cross-linked polymer films can be used to form a layer that can hold fragrance or active ingredients, which is very suitable for providing controlled release characteristics and providing long-lasting effects. These polymers can also temporarily improve unsightly fine wrinkles, thereby providing a smoother skin appearance.
Formula 3 illustrates the use of silicone elastomer gel (BRB SG 506-Dimethicone (and) Dimethicone/Vinyl Dimethicone Cross-linked Polymer) in modern CC cream formulations. It is an important development trend in Asia. For formulators, developing stable products and reasonable concentrations of color pigments and silicone oils can be a challenge. The formula cited provides a non-greasy skin feel, silky smooth touch during and after application. Silicone elastomer gels can also be used in other colored cosmetics, such as lipsticks and all types of foundations.
The silicone elastomer can be added and dispersed in the silicone phase or the oil phase before emulsification, or can be added to the emulsion afterwards. For ease of use, the viscosity can be reduced by premixing with dimethicone or cyclodisiloxane.
Considering the structure and performance of the two systems, silicone resins can be classified as organosilicates. They have a three-dimensional silicate structure, which is highly cross-linked and has a high molecular weight. One of good examples of silicone resins is siloxysilicate (Figure 6). These special compounds dry on the skin to form a sensory film, and are often used as plasticizers with other silicone oils. They are excellent waterproof additives with significant non-transfer properties and can fix the pigments in place to improve performance. They prevent particle agglomeration and maintain the free-flowing characteristics of loose powder products. They can also act as plasticizers and change the hardness/brittleness of other organic resins. They are increasingly being incorporated into sunscreen, deodorant, lipstick, mascara and foundation.
In skin care formulations, they develop long-lasting protective films for face creams, baby creams, mosquito repellents and sunscreen products. In hair care formulations, silicone resin can provide volume and beauty, and at the same time has moisture resistance to prevent loosening of straightened hair.
Hair care silicone emulsion
The global hair care product industry is still optimistic about its growth prospects for a period of time in the future, focusing on product innovation that combines the most advanced performance with natural ingredients. Conditioning and moisturizing are still key elements for hair care producers.
Hair damage is an inevitable fact in life. Chemical treatments, such as bleaching and dyeing, hair aging, heat setting, environmental and hormonal changes, can destroy the natural luster and drape, making the hair look dull and unhealthy. Conditioning is a multifaceted manifestation. In addition to other characteristics, it also includes easy combing when wet and dry, healthy appearance, gloss, softness and ease of handling. Specialty silicones can provide excellent conditioning and moisturizing effects, thereby repairing and restoring smoothness, gloss and manageability.
The combination of silicone and cationic polymers (such as polyquaternary ammonium salts, guar gum) has proven to be an advanced conditioner for hair. Many types of silicones are commonly used in hair care applications. Since silicone oil is neither soluble in water nor soluble in organic oils, its incorporation into aqueous systems has become a major challenge.
Silicone emulsions have been developed to overcome this obstacle and enable the easy incorporation of silicones without temperature and with low shear. This approach ensures that the silicone particle size distribution can be optimized for performance and stability in the final preparation. The high molecular weight silicone emulsion based on dimethiconol has excellent compatibility in aqueous solutions. In addition, these emulsions are easy to handle and improve the dispersion and distribution of the silicone on the hair. For example, CTFA-labeled dimethiconol (and) TEA-dodecylbenzene sulfonate silicone emulsion and guar gum are used in two-in-one shampoos to provide conditioning effects. This silicone emulsion incorporates 1 million cst dimethiconol dispersed in a surfactant system. In the shampoo, it improves the combability of dry and wet hair, and gives the hair a slippery and soft feel.
Another good example is methicone emulsion. Dimethicone is a cationic silicone, which contains amino functional groups on the backbone of polydimethylsiloxane, replacing some methyl functional groups. The net positive charge of methicone on the nitrogen atom varies with pH. It provides more substantial conditioning effects and has been used in leave-on and rinse-off conditioners. Aminos provide smooth softness to the hair and aid in combing.
In today's market, most personal care products contain a certain amount of silicone. Their versatility and aesthetic properties make them useful "preferred" ingredients for a variety of personal care applications from makeup to sunscreen, face, body, antiperspirant and hair conditioner. They found applications covering all brand series, from the simplest, cost-effective daily shampoo to leading and innovative anti-aging serums. By choosing the right silicone for your formulation, you can easily achieve outstanding sensory characteristics and effective product aesthetics to meet the most demanding consumer requirements.
Silicones are true cosmetic chemicals and are used in personal care applications. They make creams and lotions smooth. In shampoos, silicones can make hair softer and easier to comb. Our products include silicone formulations, silicone emulsions and surfactants. Silway is a professional manufacturer and supplier of cosmetic silicones and Polyether modified silicone oil , implementing the most stringent quality control and creating high-quality products for customers. Welcome to consult for details: /