Two-step deswelling in the Volume Phase Transition of thermoresponsive microgels

Abstract

Thermoresponsive microgels are one of the most investigated class of soft colloids, thanks to their ability to undergo a Volume Phase Transition (VPT) close to ambient temperature. However, this fundamental phenomenon still lacks a detailed microscopic understanding, particularly regarding the presence and the role of charges in the deswelling process. Here we fill this gap by combining experiments and simulations to show that the microgel collapse does not happen in a homogeneous fashion, but through a two-step mechanism, entirely attributable to electrostatic effects. The signature of this phenomenon is the emergence of a minimum in the ratio between gyration and hydrodynamic radii at the VPT. Thanks to simulations of several microgels with different cross-linker concentrations, charge contents and charge distributions, we build a unifying master-curve able to predict the two-step deswelling. Our results have direct relevance on fundamental soft condensed matter science and on microgel applications ranging from materials to biomedical technologies.

main article: 12 pages, 7 figures; supplementary materials: 11 pages, 12 figures, 2 tables

References in corpus (15)

• How to mesh up Ewald sums (I): A theoretical and numerical comparison of various particle mesh routines
• "In silico" synthesis of microgel particles
• A new look at effective interactions between microgel particles
• Microgels Adsorbed at Liquid-Liquid Interfaces: A Joint Numerical and Experimental Study
• Relationship between Rheology and Structure of Interpenetrating, Deforming and Compressing Microgels
• Numerical modelling of non-ionic microgels: an overview
• Connecting elasticity and effective interactions of neutral microgels: the validity of the Hertzian model
• Modelling microgels with controlled structure across the volume phase transition
• Recent advances in stimuli-responsive core-shell microgel particles: synthesis, characterisation, and applications
• Universal size ratios of Gaussian polymers with complex architecture: Radius of gyration vs hydrodynamic radius
• Overcharging and reentrant condensation of thermoresponsive ionic microgels
• Numerical insights on ionic microgels: structure and swelling behaviour
• Bulk and interfacial stresses in suspensions of soft and hard colloids
• Charge affinity and solvent effects in numerical simulations of ionic microgels
• Investigation of Volume Phase Transition from the Different Properties of Particles

Cited by in corpus (5)

• The role of charge content in the two-step deswelling of Poly(N-isopropylacrylamide)-based microgels
• Numerical study of neutral and charged microgel suspensions: from single-particle to collective behavior
• Hot Brownian Motion of thermoresponsive microgels in optical tweezers shows discontinuous volume phase transition and bistability
• Numerical insights on the volume phase transition of thermoresponsive hollow microgels
• Self-induced buckling in hollow microgels