Paper: Linking morphology, structure and interactions of composite microgels

SuperCol ESR Rodrigo Rivas-Barbosa from Sapienza University of Rome published a paper in Macromolecules. It describes the use of a combination of experimental and numerical methods to show that the morphology of microgels can be tuned to control their structure and interactions. This will pave the way to explore new collective behaviour in microgels.

Abstract:

We combine small-angle scattering experiments and simulations to investigate the internal structure and interactions of composite poly(N-isopropylacrylamide)–poly(ethylene glycol) (PNIPAM–PEG) microgels. At low temperatures the experimentally determined form factors and the simulated density profiles indicate a loose internal particle structure with an extended corona that can be modeled as a starlike object. With increasing temperature across the volumetric phase transition, the form factor develops an inflection that, using simulations, is interpreted as arising from a conformation in which PEG chains are incorporated in the interior of the PNIPAM network. This gives rise to a peculiar density profile characterized by two dense, separated regions, at odds with configurations in which the PEG chains reside on the surface of the PNIPAM core. The conformation of the PEG chains also have profound effects on the interparticle interactions: Although chains on the surface reduce the solvophobic attraction typically experienced by PNIPAM particles at high temperatures, PEG chains inside the PNIPAM network shift the onset of attractive interaction at even lower temperatures. Our results show that by tuning the morphology of the composite microgels, we can qualitatively change both their structure and their mutual interactions, opening the way to explore new collective behaviors of these objects.

Paper details:

Rodrigo Rivas-Barbosa, Jose Ruiz-Franco, Mayra A. Lara-Peña, Jacopo Cardellini, Angel Licea-Claverie, Fabrizio Camerin, Emanuela Zaccarelli, Marco Laurati:
Link between morphology, structure and interactions of composite microgels
Macromolecules 2022, 55, 5, 1834–1843 DOI: 10.1021/acs.macromol.1c02171