Manipulating three-dimensional gel network entanglement by thin film shearing

Area of Science:

• Supramolecular chemistry
• Materials science
• Rheology

Background:

• Supramolecular gels are formed by self-assembly of molecules into networks.
• Understanding gel response to external stimuli is crucial for applications.
• Bis-urea compounds are known gelators with tunable properties.

Purpose of the Study:

• To investigate the effect of vortex fluidic shearing on fluorous and hydrocarbon bis-urea supramolecular gels.
• To compare the shear resistance of fluorous versus non-fluorous bis-urea gelators.
• To establish a novel method for studying the mechanical disruption of gel networks.

Main Methods:

• Preparation of thin films of fluorous and hydrocarbon bis-urea supramolecular gels.
• Application of vortex fluidic mediated shearing to the gel thin films.
• Analysis of gel structure and disruption using small angle neutron scattering (SANS).

Main Results:

• Vortex fluidic shearing completely disrupted fluorous bis-urea gels.
• Hydrocarbon analogues exhibited partial disruption, indicating higher shear resistance.
• Small angle neutron scattering revealed differences in network integrity post-shearing.

Conclusions:

• Non-fluorous bis-urea gelators demonstrate significant resistance to shear-induced disruption.
• The combination of thin film shearing and SANS is an effective technique for probing gel network stability.
• Shear forces can be used to control the integrity of supramolecular gel structures.