Insights into Carbopol gel formulations: Microscopy analysis of the microstructure and the influence of polyol additives

Abstract

International audienceCarbopol is a family of high molecular weight cross-linked poyacrylic acids widely used as thickening agents in several industrial applications. In this work, the structure of Carbopol 974P NF was investigated at pH 7.4 by means of capillary viscometry, dynamic rheology, fluorescence microscopy, and electron microscopy in the dilute and semi-dilute (hydrogel) state. Especially, high-pressure freezing technique has proved to be a technique of choice to visualize the Carbopol hydrogel microstructure through cryo-scanning electron microscopy analysis without artifacts related to the formation of ice crystals. It has been shown that the Carbopol hydrogel has a hierarchical structure made of large spherical entities of a few micrometers in size packed together and composed of much smaller agglomerated microgel particles. In addition, fluorescence and electron microscopies have pointed out that the presence of polyol additives in the gel formulation favors the formation of more dense or jammed structure, probably through hydrogen bonding. (c) 2015 Wiley Periodicals, Inc

Gelation kinetics of non-aqueous Carbopol dispersions

“…Carbopol 974P NF (Lubrizol Limited) in powder form was used to prepare a polymeric dispersion in Polyethylene glycol 400 (PEG400, Ineos Oxide). This type of Carbopol is a highly-crosslinked polymer of acrylic acid cross-linked with allyl pentaerythritol [18], although specifications on the crosslinking process for Carbopol 974P NF are not known. The dispersion was prepared by adding 4% wt of Carbopol in PEG400.…”

Physico-mechanical properties of topical formulations based on different polymers

“…The carbomer AAAC was different because its lateral chain does not have a cyclic chain, so it was possible to create a better cross-linked 3D-structure, with a more compact formulation, with a large increase on physical-mechanical parameters with lower concentrations of polymer. (15)(16)(17) HEC has a smaller lateral chain when compared to the other polymers cited previously. For this reason, when the concentration is increased 2.5 times, the results of viscosity and consistency are the same as for the AAAC when it was increased 8 times.…”

Acoustic bubble dynamics in a yield-stress fluid

“…The yield-stress fluid we use in this article is a Carbopol ETD 2050 microgel (Lubrizol Corporation, Wickliffe, Ohio, USA) of concentration 0.15% w/v that has been extensively studied in the literature. 5,[35][36][37] The Carbopol primary particles are made of crosslinked polyacrylic acid, which swells at high pH to form a jammed assembly of soft particles with a diameter of several microns. 36 Following classical preparation protocols, 5,37 we first let the Carbopol flakes dissolve in MilliQ water (18.2 MO cm) for 1 hour under gentle agitation before adding 1% v/v 1 M NaOH to adjust the pH to 7.…”

“…5,[35][36][37] The Carbopol primary particles are made of crosslinked polyacrylic acid, which swells at high pH to form a jammed assembly of soft particles with a diameter of several microns. 36 Following classical preparation protocols, 5,37 we first let the Carbopol flakes dissolve in MilliQ water (18.2 MO cm) for 1 hour under gentle agitation before adding 1% v/v 1 M NaOH to adjust the pH to 7. The fluid is then stirred for 20 minutes by an overhead mixer (RW 20 fitted with a R1303 dissolver impeller, IKA, Staufen im Breisgau, Germany) at 2000 rpm.…”