Wettability Engendered Templated Self-assembly (WETS) for Fabricating Multiphasic Particles

Abstract

Precise control over the geometry and chemistry of multiphasic particles is of significant importance for a wide range of applications. In this work, we have developed one of the simplest methodologies for fabricating monodisperse, multiphasic micro- and nanoparticles possessing almost any composition, projected shape, modulus, and dimensions as small as 25 nm. The synthesis methodology involves the fabrication of a nonwettable surface patterned with monodisperse, wettable domains of different sizes and shapes. When such patterned templates are dip-coated with polymer solutions or particle dispersions, the liquids, and consequently the polymer or the particles, preferentially self-assemble within the wettable domains. Utilizing this phenomenon, we fabricate multiphasic assemblies with precisely controlled geometry and composition through multiple, layered depositions of polymers and/or particles within the patterned domains. Upon releasing these multiphasic assemblies from the template using a sacrificial layer, we obtain multiphasic particles. The templates can then be readily reused (over 20 times in our experiments) for fabricating a new batch of particles, enabling a rapid, inexpensive, and easily reproducible method for large-scale manufacturing of multiphasic particles.

The Fluid Joint: The Soft Spot of Micro‐ and Nanosystems

“…We specifically refer to the subtype of fluid bridges where at least one of the areas of contact on the supporting surfaces is constrained laterally (besides axially) as to the fluid joint (Figure e). Lateral liquid confinement on a surface (i.e., contact line pinning) can be enforced chemically, i.e., through the juxtaposition of surfaces of contrasting wetting properties ( Figure a,b), or topographically, i.e., through the machining of solid edges (Figure c,d). In both cases, liquid confinement at the pinning borders results from an extension of the canthotaxis sector.…”

“…The line can conversely recede on the lyophilic area when the angle becomes inferior to the receding static contact angle θ r1 . b) Micrometer‐sized polystyrene lenses of nanometric thickness selectively dip‐coated on lyophilic patches patterned over silanized lyophobic TiO 2 surfaces (reproduced with permission . Copyright 2015, American Chemical Society).…”

Fabrication of Hydrogel Particles of Defined Shapes Using Superhydrophobic‐Hydrophilic Micropatterns

“…15,16 However, there are still too few methods allowing for the fabrication of hydrogel particles with different geometries and dimensions and compatible with the cell encapsulation. 17 New approaches combining the encapsulation of cells into structures with complex geometries and long-term cell analysis are also required.…”

Recent Advances in TiO2‐Based Nanostructured Surfaces with Controllable Wettability and Adhesion

“…[ 117 ] Recently, Tuteja and co-authors had developed a simple wettability engendered templated self-assembly (WETS) methodology for preparing monodisperse, multi-phasic micro/nano-particles ( Figure 15 ). [ 118 ] The synthesis methodology involved the construction of a non-wettable substrate patterned with wettable domains of different sizes and shapes by taking advantage of photocatalytic activity of TiO 2 . When such patterning templates were dipcoated with dispersed polymer or particle solutions, and consequently the polymer or the particles would preferentially self-assembled within the wettable regions.…”