Manufacturing Nanoparticles with Orthogonally Adjustable Dispersibility in Hydrocarbons, Fluorocarbons, and Water

Abstract

We describe a universal wet‐chemical shell‐by‐shell coating procedure resulting in colloidal titanium dioxide (TiO2) and iron oxide (Fe3O4) nanoparticles with dynamically and reversibly tunable surface energies. A strong covalent surface functionalization is accomplished by using long‐chained alkyl‐, triethylenglycol‐, and perfluoroalkylphosphonic acids, yielding highly stabilized core–shell nanoparticles with hydrophobic, hydrophilic, or superhydrophobic/fluorophilic surface characteristics. This covalent functionalization sequence is extended towards a second noncovalent attachment of tailor‐made nonionic amphiphilic molecules to the pristine coated core–shell nanoparticles via solvophobic (i.e. either hydrophobic, lipophobic, or fluorophobic) interactions. Thereby, orthogonal tuning of the surface energies of nanoparticles via noncovalent interactions is accomplished. As a result, this versatile bilayer coating process enables reversible control over the colloidal stability of the metal oxide nanoparticles in fluorocarbons, hydrocarbons, and water.

Multifunctional and Tunable Surfaces Based on Pyrene Functionalized Nanoparticles

“…The ligands of the second shell are thought to interact with the core–shell system via solvophobic interactions, which in the case of the matrix PAs PA‐CH 3 and PA‐CF 3 are based on hydrophobic interactions. In this context, SDBS is utilized to transfer lipophilic AlO x @10%PA‐Py/PA‐CH 3 core–shell systems to a lipophobic and Pyr + ‐CF 3 (Figure ) and to transfer fluorophilic AlO x @10%PA‐Py/PA‐CF 3 to a fluorophobic solvent such as H 2 O, respectively.…”

“…Second shell formation was followed by means of dynamic light scattering and zeta potential measurements as previously described by Zeininger et al Considering the versatility of pyrene derivatives in terms of sensing their chemical environments, formation of a second shell bears the potential to impact the optical properties of core–shell NPs ( Figure ). Taking, for example, AlO x @10%PA‐Py/PA‐CH 3 in H 2 O, a slight increase in the 350 nm absorption occurs upon SDBS addition.…”

Electronic Communication in Confined Space Coronas of Shell‐by‐Shell Structured Al2O3 Nanoparticle Hybrids Containing Two Layers of Functional Organic Ligands

“…Subsequently, the mono‐shell‐functionalized NPs were subjected to a second, in this case non‐covalent, functionalization by treatment with the amphiphiles A 1 , A 2 , or A 3 and simultaneous dispersion of the reaction products [Al 2 O 3 ‐(PAR 2–4 X % PAR 1 (100− X )% )]A 1–3 in water or hexafluorobenzene, respectively (Scheme and ). During this procedure a polarity umpolung induced by the second ligand shell takes place according to the new supramolecular construction concept that we have reported recently . As a result, a micellar arrangement formed involving lipophilic interactions between the nonpolar parts (R 1 –R 4 ) of the first layer and the lipophilic termini of A 1–3 .…”

Responsive drop method: quantitativein situdetermination of surfactant effectiveness using reconfigurable Janus emulsions

“…Surfactants, including emulsifiers, detergents, dispersants, and foaming, wetting, and coating agents are technologically commonplace on the largest scale as they play an important role in cleaning, manufacturing, oil recovery, and other processes. [1][2][3][4] Surfactants are designed to lower the surface tension of liquidliquid, liquid-gas, or solid-liquid interfaces and are therefore central components of many medical, cosmetic, food, consumer, and performance materials. 5 Crucial to selecting a suitable surfactant for a specific application is a thorough investigation and characterization of its effectiveness that includes the determination of key parameters such as its critical micelle concentration (CMC) as well as its potential to lower the surface tension at interfaces.…”