[Soft Matter Café] Rheology and Phase Behaviour of Interpenetrated Polymer Network Microgels

Multi-responsive microgels are widely studied hybrid systems that combine the properties of polymers and colloids. Due to their complex morphology, the microscopic interactions of these soft particles are still not completely understood. Combining rheometry [1,2], differential scanning calorimetry [3] and small angle neutron scattering, we investigated a thermo- and pH-sensitive microgel composed of Interpenetrated Polymer Network (IPN) of poly(N-isopropylacrylamide) (PNIPAM) and poly(acrylic acid) (PAAc) at fixed PAAc content as a function of weight concentration. We found three different rheological regimes characteristic of three different states: a Newtonian shear-thinning fluid, an attractive glass characterized by a yield stress, and a jamming state. A preliminary T- Cw phase diagram is here shown.

[1]  S. Franco, et al., International journal of molecular sciences 22 (8), 4032 (2021)
[2]  S. Franco, et al., Journal of Physics: Condensed Matter 33 (17), 174004 (2021)
[3]  S. Franco, et al., Polymers 14 (1), 115 (2022)