Carbomer is a popular raw material in the chemical industry. It is a high-molecular polymer material. It is usually used as a thickener, gel, and suspending agent in creams and emulsions for daily chemical products. It is also listed in the Pharmacopoeia. Pharmaceutical auxiliary materials are used as dispersants, diluents or carriers for medicinal ingredients, as well as additives for animal feed in food.
The reason why carbomer has a good gel and thickening effect is because of its special molecular structure. Carbomer is a kind of polyacrylic acid material, which can also be regarded as carboxyvinyl. The bond position for polymerization is the carbon-carbon double bond of olefin, and the carboxyl group remains.
Carbomer gel performance and stability judgment
When the carbomer dissolves in water, the carboxyl group ionizes the hydrogen ion and shows a negative charge. The carboxyl group and the carboxyl group in the molecule repel each other with the same charge, so that the molecule slowly expands, which makes the carbomer have good swelling properties in water . It takes a long time for water molecules to diffuse into the carbomer molecules, and after swelling, a gel with a higher viscosity will be formed. When the pH is 6-11, the viscosity of the gel is relatively high. When the pH is 8, the carboxyl groups in the molecule are basically completely dissociated, the repulsive force in the molecule increases to the maximum, and the viscosity reaches the maximum.
When carbomer is dissolved in water to prepare a gel, it is best to soak it in deionized water for 24 hours, and then mechanically stir it for half an hour. Neutralizing carbomer usually uses triethanolamine and EDTA-2Na as gel stabilizers. The presence of the hydration film on the surface of the carbomer gel makes the gel relatively stable. The greater the degree of dissociation of the carboxyl group, the less free water content in the gel and the less likely to grow bacteria. The degree of hydration of the gel can be judged by the sliding time of the gel on the wall of the beaker. Products with the same viscosity but different hydration speeds indicate different gel stability.
From the above content, it can be concluded that the gel performance or viscosity of carbomer is adjusted by the pH value of the gel, and the viscosity is maximum when the optimal pH value is reached; the stability of the gel can be determined by the degree of hydration. Judge, and adjust and control. The carbomers produced by Desheng are divided into 940 and 980 types, which can be selected according to their own needs and sample test conditions.
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