Soft synthetic microgels as mimics of mycoplasma

Büning, Dominic; Schumacher, J.; Helling, Alexander; Chakroun, Ramzi; Ennen-Roth, Franka; Gröschel, André H.; Thom, Volkmar; Ulbricht, Mathias

doi:10.1039/d1sm00379h

Cited by 3 publications

(3 citation statements)

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“…Nanoparticles’ softness further concerns their behavior during filtration , and drying processes . Indeed, the knowledge on the nanogel characteristics and their solvent activity are essential to understand transport phenomena through dense soft and permeable nanoparticles dispersions.…”

Section: Discussionmentioning

confidence: 99%

How Softness Matters in Soft Nanogels and Nanogel Assemblies

et al. 2022

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Softness plays a key role in determining the macroscopic properties of colloidal systems, from synthetic nanogels to biological macromolecules, from viruses to star polymers. However, we are missing a way to quantify what the term “softness” means in nanoscience. Having quantitative parameters is fundamental to compare different systems and understand what the consequences of softness on the macroscopic properties are. Here, we propose different quantities that can be measured using scattering methods and microscopy experiments. On the basis of these quantities, we review the recent literature on micro- and nanogels, i.e. cross-linked polymer networks swollen in water, a widely used model system for soft colloids. Applying our criteria, we address the question what makes a nanomaterial soft? We discuss and introduce general criteria to quantify the different definitions of softness for an individual compressible colloid. This is done in terms of the energetic cost associated with the deformation and the capability of the colloid to isotropically deswell. Then, concentrated solutions of soft colloids are considered. New definitions of softness and new parameters, which depend on the particle-to-particle interactions, are introduced in terms of faceting and interpenetration. The influence of the different synthetic routes on the softness of nanogels is discussed. Concentrated solutions of nanogels are considered and we review the recent results in the literature concerning the phase behavior and flow properties of nanogels both in three and two dimensions, in the light of the different parameters we defined. The aim of this review is to look at the results on micro- and nanogels in a more quantitative way that allow us to explain the reported properties in terms of differences in colloidal softness. Furthermore, this review can give researchers dealing with soft colloids quantitative methods to define unambiguously which softness matters in their compound.

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Section: Discussionmentioning

confidence: 99%

How Softness Matters in Soft Nanogels and Nanogel Assemblies

et al. 2022

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“…For most colloidal dispersions, the corresponding osmotic pressures are well below Their softness comes into play at higher concentrations due to their ability to interpenetrate, deform, and deswell (29)(30)(31). The extent of deswelling and deformation for a given mesostructure is determined by water activity within microgels (22,32,33), which significantly varies with water concentration (34,35). The interplay between mesostructure and intermolecular interactions notably determines the value of water permeability of microgel filter cakes in the context of filtration processes (22,32,33).…”

mentioning

confidence: 99%

“…The extent of deswelling and deformation for a given mesostructure is determined by water activity within microgels (22,32,33), which significantly varies with water concentration (34,35). The interplay between mesostructure and intermolecular interactions notably determines the value of water permeability of microgel filter cakes in the context of filtration processes (22,32,33). Drying microgel dispersions, which allows them to reach high microgel concentrations, should thus provide an efficient means to probe this generic interplay between water transport, water activity, and microgel mesostructure.…”

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confidence: 99%

How the interplay of molecular and colloidal scales controls drying of microgel dispersions

Roger

Crassous

2021

Proc. Natl. Acad. Sci. U.S.A.

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Bringing an aqueous dispersion or solution into open air leads to water evaporation. The resulting drying process initiates the buildup of spatial heterogeneities, as nonvolatile solutes and colloids concentrate. Such composition gradients associate with mesostructure gradients, which, in turn, impact flows within these multicomponent systems. In this work, we investigate the drying of microgel dispersions in respect to two reference systems, a colloidal dispersion and a polymer solution, which, respectively, involve colloidal and molecular length scales. We evidence an intermediate behavior in which a film forms at the air/liquid interface and is clearly separated from bulk by a sharp drying front. However, complex composition and mesostructure gradients develop throughout the drying film, as evidenced by Raman and small-angle X-ray scattering mapping. We show that this results from the soft colloidal structure of microgel, which allows them to interpenetrate, deform, and deswell. As a result, water activity and water transport are drastically decreased in the vicinity of the air/liquid interface. This notably leads to diffusional drying kinetics that are nearly independent on the air relative humidity. The interplay between water fraction, water activity, and mesostructure on water transport is generic and, thus, shown to be pivotal in order to master evaporation in drying complex fluids.

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