Viscoelastic properties of pNIPAM-hydrogels: A mode-coupling theory study

Area of Science:

• Polymer Science
• Materials Science
• Rheology

Background:

• Poly(N-isopropylacrylamide) (pNIPAM) hydrogels exhibit thermosensitive behavior.
• Understanding hydrogel viscoelasticity is crucial for applications.
• Glutaraldehyde is a common cross-linker for hydrogel formation.

Purpose of the Study:

• To investigate the viscoelastic properties of glutaraldehyde-cross-linked pNIPAM hydrogels.
• To determine the influence of monomer-to-cross-linker ratio on hydrogel rheology.
• To explore the effect of temperature on the tunable properties of pNIPAM hydrogels.

Main Methods:

• Small amplitude oscillatory shear experiments.
• Steady shear rheological measurements.
• Analysis using a rescaled F12-model and mode-coupling theory.

Main Results:

• Viscoelastic properties are highly dependent on the monomer and glutaraldehyde ratio.
• Temperature acts as an effective external stimulus to tune rheological behavior.
• Experimental data aligns with theoretical predictions from the F12-model.

Conclusions:

• Glutaraldehyde-cross-linked pNIPAM hydrogels offer tunable viscoelasticity.
• Rheological characterization provides insights into hydrogel network structure.
• The study demonstrates a method for predicting hydrogel behavior based on composition and temperature.