0000000000483063
AUTHOR
Tatiana I Morozova
In Silico Design Enables the Rapid Production of Surface-Active Colloidal Amphiphiles
A new technology platform built on the integration of theory and experiments to enable the design of Janus colloids with precision control of surface anisotropy and amphiphilicity could lead to a disruptive transformation in the next generation of surfactants, photonic or phononic materials, and coatings. Here, we exploit molecular dynamics (MD) simulations to guide the rational design of amphiphilic polymer Janus colloids by Flash NanoPrecipitation (FNP), a method capable of the production of colloids with complex structure without the compromise of reduced scalability. Aided by in silico design, we show in experiments that amphiphilic Janus colloids can be produced using a unique blend of…
On the Stability of Polymeric Nanoparticles Fabricated through Rapid Solvent Mixing.
We study the stability of polymeric nanoparticles fabricated through the rapid mixing of polymers in a good solvent with a poor solvent that is miscible with the good solvent. In previous experiments where water was used as the poor solvent, a negative surface charge was measured on the precipitated nanoparticles, which led to the long-time stability of the dispersion. It was argued that these charges originate presumably from either water or hydroxide adsorption at the hydrophobic nanoparticle surface or from impurities in the feed streams that preferentially adsorb on the precipitated nanoparticles. To elucidate the origin of this stabilization mechanism, we performed experiments wherein …
Surface Activity of Soft Polymer Colloids
We investigate the behavior of polymer colloids at the interface between two immiscible liquids using molecular dynamics simulations. We study several colloid morphologies with various degrees of amphiphilicity, that is, purely solvophobic homogeneous and Janus particles and amphiphilic Janus and core-shell particles. Regardless of the specific morphology, the polymer colloids irreversibly anchor at the liquid-liquid interface, accompanied by a marked reduction of the interfacial tension, γ. Purely solvophobic particles lower γ because they reduce the interfacial area shared by the two immiscible liquids, whereas amphiphilic colloids have an additional enthalpic contribution. At the liquid-…
Coil-Globule Collapse of Polystyrene Chains in Tetrahydrofuran-Water Mixtures.
We study the coil and globule states of a single polymer chain in solution by performing molecular dynamics simulations with a united atom model. Specifically, we characterize the structural properties of atactic polystyrene chains with N = 20–150 monomers in tetrahydrofuran–water mixtures at varying mixing ratios. We find that the hydrophobic polymers form rather open coils when the mole fraction of water, XW, is roughly below 0.25, whereas the chains collapse into globules when XW ≳ 0.75. We confirm the theoretically expected scaling laws for the radius of gyration, Rg, in these regimes, i.e., Rg ∝ N3/5 and Rg ∝ N1/3 for good and poor solvent conditions, respectively. For poor solvent con…