Thixotropic Gels that Rapidly Regain Viscoelasticity Following Mechanical Stress

Categories: “Chemistry“

Reference #: 2007-037

OTC Contact: Zeinab Abouissa. (Directory Information | Send a Message)

Description

Thixotropic organogels have been used for a number of applications including as thickening agents for foods and cosmetics, pharmaceutical fillers, medical device components and paint additives. A common drawback to thixotropic gels is that after being exposed to high strain, they often do not regain their viscoelastic properties or it takes minutes to hours before recovery. Researchers have discovered that certain low molecular mass organogelators (LMOGs) that are derivatives of 12-hydroxystearic acid (HSA), form gel compositions that can regain their viscoelasticity in a matter of seconds after mechanical disruption. This advantageous property gives these gels the unique potential for use in materials that experience high stress. Therefore, compositions of this invention may be superior substitutes for HSA organogels in certain applications.

Applications

Novel thixotropic organogels may be especially useful in materials that require elastic properties and experience high mechanical stress.

Advantages

• HSA derivative gels demonstrate an unprecedented fast recovery of viscoelasticity following mechanical stress
• LMOGs of this invention form gels form at low concentrations in a variety of liquids
• After mechanical stress, gels of the invenDavidtion retain their elastic properties

Stage of Development

Thixotropic gels have been made with a variety of amide and amine HSA derivatives in different solvents including, silicon oil, toluene and DMSO. Gelation was observed at concentrations below 1.0 wt. % for LMOGs of the invention in silicon oil. In a particular example, an amide derivative of HSA (2 wt. % in silicone oil) showed a 90% recovery in its storage modulus (G1) value after mechanical stress, while HSA (2 wt. % in silicone oil) showed less than a 70% recovery of G1. Furthermore, recovery occurred in less than 10 seconds.

Relevant Publications

“Robust Organogels from Nitrogen-Containing Derivatives of (R)-12-Hydroxystearic Acid as Gelators:
Comparisons with Gels from Stearic Acid Derivatives.” Langmuir. 2009, ASAP online.

Patent Status

Applications Pending