BIOPOL® Polymers are water soluble crosslinked Polyacrylic Acid. It is offered as fluffy dry white powder.
BIOPOL® polymers have been used for over 50 years for various applications with the highest quality carbomers on the market. Their application in products as rheology modifiers, tablet binders, suspension stabilizers, thickeners, extended release polymers, mucoadhesive aids, bioavailability enhancers have increased their demand as they are versatile and their ease of use has created its demand in Pharmaceutical, Nutraceutical, Personal Care & Allied Industrial applications. Grades within the BIOPOL® family are chemically similar in terms of the fact that they are all high molecular weight, crosslinked polyacrylic acid polymers. However, these gel forming polymers differ by their chemical crosslinking and can be grouped
into 3 categories.
Our passion & mission to enhance our product performance & quality over time has helped us address the regulatory demands, increase product robustness & flexibility and improve product handling, especially during mixing/processing and increase the ease of polymer dispersion to cut down on processing time. Our entire range of BIOPOL® carbomer family are synthesized without Benzene - a substance that is increasingly restricted for use in pharmaceutical excipient applications as well as is harmful for topical applications on repeated use. Our entire range of carbomers are synthesized in Methylene Chloride only within the range of Pharmacopoeia & maintaining it much below the maximum allowed limit for higher safety levels.
BIOPOL® is manufactured via suspension polymerization. The polymeric powder is separated from the polymerization medium, purified and dried to the required specifications.
Each particle (about 0.2 micron in diameter with an average agglomerate size of 2-7 microns) is a network structure of polymer chains chemically connected by crosslinks (shown in figure 1).
When in contact with water, hydration starts to uncoil the polymer network of BIOPOL®. This results in an increase in viscosity of the aqueous dispersion (BIOPOL® polymer is not soluble in water but becomes swollen in water). To achieve full viscosity, it is necessary to complete the uncoiling of the polymer chain network. Complete uncoiling is achieved by neutralizing the carboxylic acid groups with a base (an alkali or amine); the resulting anionic charge on the polymer chain creates repulsive forces that rapidly uncoil the network to an extended structure, therefore attaining maximum thickening efficiency (Figure 2).
As described above, the viscosity of BIOPOL® in water (for example) will increase upon neutralization with a base (such as sodium hydroxide/Tri-ethanolamine). With variation in pH, the viscosity of the aqueous dispersion decreases drastically. This effect is due to the presence of excessive ions. Therefore, care must be taken to avoid overshooting the pH in order to maintain the maximum thickening efficiency.
There are many types of bases (i.e. neutralizing agents) available commercially. Hydroxides of sodium, potassium and ammonium are the most common inorganic bases for use in an aqueous system. For hydroalcoholic systems, the choice of a neutralizing agent depends on the hydrophilicity of the medium to be thickened (i.e. hydrophilicity decreases with increasing the amount of alcohol in the medium). The hydrophilicity of the neutralizing agent chosen will decrease with increasing amount of alcohol in the medium.
The same principle holds for thickening organic solvents; an organic amine is recommended. BIOPOL® can be used to thicken a variety of polyhydroxy solvents (such as diols, triols and polyols) without a neutralizing agent since the thickening mechanism is hydrogen bonding. In many cases, the use of dual neutralizing agents (inorganic and organic) can be useful for an emulsion system.