Phase Transitions in Polymeric Gels Induced by Crosslinking Entropy

Microgels are polymer-based particles which can change size and shape during volume phase transitions in response to external stimuli. We have specifically investigated microgels which respond to changes in temperature. Hydrodynamic radii were obtained from light scattering data on Hydroxypropylcellulose (HPC) microgels and then modelled with the standard Flory-Huggins theory. We present a numerical study of a thermodynamic theory (M. Kaufman, Entropy, 20(7), 501, 2018) which includes the entropy associated with crosslinking between polyfunctionals and monomers at the ends of linear polymers. This theory predicts a strong first-order transition due to the saturation of possible crosslinks when the number of polyfunctionals is of the same order of magnitude as the number of polymers. We will present numerical results based on this thermodynamic model.