Exploring the colloid-to-polymer transition for ultra-low crosslinked microgels from three to two dimensions
Abstract
Microgels are solvent-swollen nano- and microparticles that show prevalent colloidal-like behavior despite their polymeric nature. Here we study ultra-low crosslinked poly(N-isopropylacrylamide) microgels (ULC), which can behave like colloids or flexible polymers depending on dimensionality, compression or other external stimuli. Small-angle neutron scattering shows that the structure of the ULC microgels in bulk aqueous solution is characterized by a density profile that decays smoothly from the center to a fuzzy surface. Their phase behavior and rheological properties are those of soft colloids. However, when these microgels are confined at an oil-water interface, their behavior resembles that of flexible macromolecules. Once monolayers of ultra-low crosslinked microgels are compressed, deposited on solid substrate and studied with atomic-force microscopy, a concentration-dependent topography is observed. Depending on the compression, these microgels can behave as flexible polymers, covering the substrate with a uniform film, or as colloidal microgels leading to a monolayer of particles. Show more
Permanent link
https://doi.org/10.3929/ethz-b-000337147Publication status
publishedExternal links
Journal / series
Nature CommunicationsVolume
Pages / Article No.
Publisher
NatureOrganisational unit
09455 - Isa, Lucio / Isa, Lucio
Funding
144646 - Two-dimensional self-assembled materials at liquid interfaces: basics, shear and patches (SNF)
172913 - Complex colloids assembled using capillary interactions: a new route towards active materials (SNF)
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